Advanced Loan & Mortgage Calculator

Executive Summary

The Advanced Loan & Mortgage Calculator is a comprehensive financial planning tool that transforms complex loan mathematics into clear, actionable insights. Whether you’re considering a home purchase, refinancing an existing mortgage, or evaluating any type of installment loan, this calculator provides everything you need: accurate monthly payment calculations, total interest costs, detailed amortization schedules, and interactive visualizations showing how your payments are allocated between principal and interest over time.

What distinguishes this advanced calculator from basic mortgage tools is its depth of analysis and presentation. Beyond simply calculating a monthly payment, it generates a complete amortization schedule showing how each payment is applied, reveals the total cost of borrowing over the loan lifetime, and allows CSV export for integration into your personal financial planning spreadsheets. The interactive charts visualize your loan’s principal-to-interest ratio evolution, helping you understand exactly how debt repayment works.

This tool is indispensable for home buyers comparing different loan terms, homeowners considering refinancing opportunities, real estate investors analyzing property deals, and anyone managing installment debt. It can calculate mortgage payments including property taxes and insurance (PITI—Principal, Interest, Taxes, Insurance), evaluate the impact of different down payments, compare 15-year versus 30-year mortgages, and model extra payment scenarios to determine interest savings.

For comprehensive financial planning, combine this tool with our Advanced ROI & Profitability Calculator to evaluate whether purchasing or renting makes better financial sense, our Interactive Savings Goal Calculator to plan your down payment savings strategy, and our Investment Growth & Compound Interest Calculator to compare mortgage costs against investment returns.

Feature Tour

Core Calculation Features

1. Monthly Payment Calculation The calculator uses the standard amortization formula to determine your precise monthly payment based on loan amount, interest rate, and loan term. This calculation accounts for compound interest and ensures your loan is completely paid off by the final payment.

2. Complete Amortization Schedule View a detailed month-by-month breakdown of every payment throughout your loan term. The amortization schedule shows:

• Payment number and date
• Monthly payment amount (consistent for fixed-rate loans)
• Principal portion (increases over time)
• Interest portion (decreases over time)
• Remaining balance after each payment

This schedule reveals the true mechanics of your loan, showing how early payments are predominantly interest while later payments increasingly pay down principal.

3. Total Interest Calculation See the complete cost of borrowing—the total interest you’ll pay over the entire loan life. This often eye-opening figure reveals the true cost of financing and motivates strategies for reducing interest through extra payments or shorter loan terms.

4. Principal vs. Interest Visualization Interactive charts display how your payment allocation evolves over time. Watch as the interest portion steadily decreases while the principal portion increases, illustrating the benefits of time and consistent payments.

5. Flexible Loan Parameters

• Loan Amount: Enter any principal amount for mortgages, auto loans, personal loans, or business loans
• Interest Rate: Input annual percentage rate (APR) with decimal precision
• Loan Term: Select terms from 1 to 40 years (or custom months)
• Additional Costs: Add property taxes, homeowners insurance, and HOA fees to calculate true monthly housing costs

Advanced Features

CSV Export Capability Download your complete amortization schedule as a CSV file for import into Excel, Google Sheets, or financial planning software. This enables custom analysis, visualization, and integration with your broader financial plans.

Multiple Scenario Comparison Calculate and compare different loan scenarios side-by-side:

• 15-year vs. 30-year mortgages
• Different down payment amounts
• Current rate vs. refinance rate
• Conventional vs. adjustable-rate mortgages

Extra Payment Analysis Model the impact of additional principal payments:

• Annual lump-sum payments (bonuses, tax refunds)
• Monthly extra payments
• One-time extra payments
• See exactly how much interest you’ll save and how quickly you’ll achieve debt freedom

Property Tax and Insurance Integration For mortgage calculations, include:

• Annual property tax estimates
• Homeowners insurance premiums
• Private Mortgage Insurance (PMI) if down payment is less than 20%
• HOA fees The calculator provides your true monthly housing payment (PITI), not just the mortgage portion.

Accessibility Features

• Full keyboard navigation (Tab, Arrow keys, Enter)
• Screen reader compatible with descriptive ARIA labels
• High-contrast mode for visibility
• Mobile-responsive design for calculations anywhere
• Touch-friendly controls for tablet and smartphone users

Understanding Your Results

The calculator presents multiple perspectives on your loan:

Summary View: Quick overview showing monthly payment, total interest, and total amount paid over loan life.

Detailed Amortization: Month-by-month breakdown showing the gradual shift from interest-heavy to principal-heavy payments.

Cumulative Totals: Track cumulative interest paid and remaining principal balance over time.

Visual Analytics: Charts and graphs illustrating payment composition and balance reduction timeline.

Usage Scenarios

Scenario 1: First-Time Home Buyer Comparing Loan Terms

Context: Sarah is purchasing her first home for $350,000 with a 20% down payment ($70,000). She’s comparing 15-year and 30-year mortgage options at 6.5% APR.

Process:

1. 30-Year Mortgage Calculation:

   • Loan amount: $280,000 ($350,000 - $70,000)
   • Interest rate: 6.5% APR
   • Loan term: 30 years (360 months)
   • Monthly payment: $1,770
   • Total interest: $357,200
   • Total paid: $637,200

2. 15-Year Mortgage Calculation:

   • Same loan amount and rate
   • Loan term: 15 years (180 months)
   • Monthly payment: $2,438
   • Total interest: $158,840
   • Total paid: $438,840

Analysis:

• 30-year: Lower monthly payment ($1,770) but much higher total interest ($357,200)
• 15-year: Higher monthly payment ($2,438) but saves $198,360 in interest
• Monthly difference: $668 more for the 15-year loan
• Decision factor: Can Sarah afford the extra $668/month?

Outcome: Sarah reviews the amortization schedules and realizes the 30-year mortgage interest exceeds the home’s down payment. She opts for the 15-year loan, saving nearly $200,000 despite the higher monthly payment. She uses the amortization schedule to plan her budget, knowing exactly when she’ll achieve debt freedom.

Scenario 2: Refinancing Decision Analysis

Context: Marcus has a $250,000 mortgage at 7.5% APR with 22 years remaining. Current rates have dropped to 5.5%, and he’s evaluating whether refinancing makes sense given $5,000 in closing costs.

Process:

1. Current Mortgage (Remaining):

   • Balance: $250,000
   • Interest rate: 7.5% APR
   • Remaining term: 22 years
   • Monthly payment: $1,932
   • Total interest remaining: $259,040

2. Refinance Option (20-Year):

   • Loan amount: $255,000 ($250,000 + $5,000 closing costs)
   • Interest rate: 5.5% APR
   • Term: 20 years
   • Monthly payment: $1,751
   • Total interest: $165,240

Analysis:

• Monthly savings: $181/month
• Interest saved: $93,800 over loan life
• Break-even: $5,000 closing costs ÷ $181 monthly savings = 28 months
• Additional benefit: Loan pays off 2 years sooner

Outcome: Marcus refinances, saving $181 monthly and $93,800 total. The amortization schedule confirms the math, showing his break-even point at month 28. He exports the CSV to track progress monthly.

Scenario 3: Investment Property Cash Flow Analysis

Context: Real estate investor Chen is analyzing a $300,000 rental property purchase. She needs to ensure rental income exceeds mortgage payments and expenses.

Process:

1. Loan Calculation:

   • Purchase price: $300,000
   • Down payment: $60,000 (20%)
   • Loan amount: $240,000
   • Interest rate: 7.0% APR (investment property rate)
   • Loan term: 30 years
   • Monthly P&I payment: $1,597

2. Total Monthly Costs:

   • Mortgage P&I: $1,597
   • Property taxes: $350/month
   • Insurance: $125/month
   • HOA fees: $75/month
   • Total monthly cost: $2,147

3. Cash Flow Analysis:

   • Expected rental income: $2,600/month
   • Monthly expenses: $2,147
   • Monthly cash flow: $453
   • Annual cash flow: $5,436

Outcome: The calculator confirms positive cash flow, making this a viable investment. Chen exports the amortization schedule to model equity buildup over 10 years, determining the property will build approximately $47,000 in equity while generating $54,360 in cash flow—a compelling investment. She pairs this analysis with our Advanced ROI & Profitability Calculator to calculate her annualized return including appreciation and cash flow.

Scenario 4: Auto Loan Comparison

Context: David is buying a $35,000 car and comparing dealer financing (5.9% for 72 months) against credit union financing (4.5% for 60 months).

Process:

1. Dealer Financing (72 months):

   • Loan amount: $35,000
   • Interest rate: 5.9% APR
   • Term: 72 months
   • Monthly payment: $586
   • Total interest: $7,192
   • Total paid: $42,192

2. Credit Union Financing (60 months):

   • Loan amount: $35,000
   • Interest rate: 4.5% APR
   • Term: 60 months
   • Monthly payment: $652
   • Total interest: $4,117
   • Total paid: $39,117

Analysis:

• Dealer: Lower monthly payment but $3,075 more in interest
• Credit Union: $66 higher monthly payment but saves $3,075 and pays off 12 months sooner
• True cost comparison visible in amortization schedules

Outcome: David chooses credit union financing, saving $3,075 and owning his car free and clear a year earlier. The amortization schedule shows him paying predominantly principal in the final years, motivating him to make extra payments when possible.

Scenario 5: Extra Payment Impact Analysis

Context: Lisa has a $200,000 mortgage at 6.0% APR for 30 years. She receives a $5,000 annual bonus and wonders about the impact of applying it to her mortgage principal.

Process:

1. Standard Payment Plan:

   • Monthly payment: $1,199
   • Total interest: $231,640
   • Payoff: 360 months (30 years)

2. With $5,000 Annual Extra Payment:

   • Use calculator’s extra payment feature
   • Apply $5,000 annually to principal
   • New payoff: approximately 18 years
   • Total interest: approximately $123,500
   • Interest saved: $108,140

Analysis:

• Paying off mortgage 12 years early
• Saving over $108,000 in interest
• $5,000 annual payments = $90,000 total extra payments
• Net benefit: $108,140 savings - $90,000 extra = $18,140 pure savings
• Plus 12 years of payment-free living

Outcome: The dramatic impact motivates Lisa to commit to annual extra payments. She exports the revised amortization schedule, circling the new payoff date (her 50th birthday) as a major financial milestone. This strategy pairs perfectly with our Interactive Savings Goal Calculator to ensure she reserves funds for the annual payments.

Code Examples

Example 1: Basic Monthly Payment Calculation

// Calculate monthly mortgage payment using amortization formula
function calculateMonthlyPayment(principal, annualRate, years) {
  const monthlyRate = annualRate / 100 / 12;
  const numberOfPayments = years * 12;
  
  // Amortization formula: M = P[r(1+r)^n]/[(1+r)^n-1]
  const monthlyPayment = principal * 
    (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) /
    (Math.pow(1 + monthlyRate, numberOfPayments) - 1);
  
  return monthlyPayment;
}

// Example: $300,000 loan at 6.5% for 30 years
const payment = calculateMonthlyPayment(300000, 6.5, 30);
console.log(`Monthly Payment: $${payment.toFixed(2)}`); // $1,896.20

Example 2: Generate Complete Amortization Schedule

// Generate full amortization schedule
function generateAmortizationSchedule(principal, annualRate, years) {
  const monthlyRate = annualRate / 100 / 12;
  const numberOfPayments = years * 12;
  const monthlyPayment = calculateMonthlyPayment(principal, annualRate, years);
  
  let balance = principal;
  const schedule = [];
  
  for (let month = 1; month <= numberOfPayments; month++) {
    const interestPayment = balance * monthlyRate;
    const principalPayment = monthlyPayment - interestPayment;
    balance -= principalPayment;
    
    schedule.push({
      month: month,
      payment: monthlyPayment,
      principal: principalPayment,
      interest: interestPayment,
      balance: Math.max(0, balance) // Prevent negative due to rounding
    });
  }
  
  return schedule;
}

// Example usage
const schedule = generateAmortizationSchedule(250000, 6.0, 30);
console.log('First Payment:', schedule[0]);
console.log('Last Payment:', schedule[schedule.length - 1]);

// Output shows progression from interest-heavy to principal-heavy

Example 3: Calculate Total Interest Paid

// Calculate total interest over loan life
function calculateTotalInterest(principal, annualRate, years) {
  const monthlyPayment = calculateMonthlyPayment(principal, annualRate, years);
  const totalPaid = monthlyPayment * years * 12;
  const totalInterest = totalPaid - principal;
  
  return {
    monthlyPayment: monthlyPayment,
    totalPaid: totalPaid,
    totalInterest: totalInterest,
    interestPercentage: (totalInterest / principal) * 100
  };
}

// Compare different loan terms
const terms = [15, 20, 25, 30];
const principal = 300000;
const rate = 6.5;

console.log('Loan Comparison for $300,000 at 6.5%:\n');
terms.forEach(term => {
  const result = calculateTotalInterest(principal, rate, term);
  console.log(`${term}-Year Loan:`);
  console.log(`  Monthly Payment: $${result.monthlyPayment.toFixed(2)}`);
  console.log(`  Total Interest: $${result.totalInterest.toFixed(2)}`);
  console.log(`  Interest as % of Principal: ${result.interestPercentage.toFixed(1)}%\n`);
});

Example 4: Extra Payment Impact Analysis

// Calculate loan payoff with extra monthly payments
function calculateWithExtraPayment(principal, annualRate, years, extraMonthlyPayment) {
  const monthlyRate = annualRate / 100 / 12;
  const regularPayment = calculateMonthlyPayment(principal, annualRate, years);
  const totalPayment = regularPayment + extraMonthlyPayment;
  
  let balance = principal;
  let month = 0;
  let totalInterest = 0;
  
  while (balance > 0) {
    month++;
    const interestPayment = balance * monthlyRate;
    const principalPayment = Math.min(totalPayment - interestPayment, balance);
    
    totalInterest += interestPayment;
    balance -= principalPayment;
  }
  
  const standardResult = calculateTotalInterest(principal, annualRate, years);
  const interestSaved = standardResult.totalInterest - totalInterest;
  const monthsSaved = (years * 12) - month;
  
  return {
    monthsToPayoff: month,
    yearsSaved: monthsSaved / 12,
    totalInterest: totalInterest,
    interestSaved: interestSaved
  };
}

// Example: $250,000 loan at 6% for 30 years with $200 extra monthly
const result = calculateWithExtraPayment(250000, 6.0, 30, 200);
console.log(`Extra Payment Impact ($200/month):`);
console.log(`  Payoff in ${result.monthsToPayoff} months`);
console.log(`  Time saved: ${result.yearsSaved.toFixed(1)} years`);
console.log(`  Interest saved: $${result.interestSaved.toFixed(2)}`);

Example 5: Compare Multiple Loan Scenarios

// Comprehensive loan comparison tool
function compareLoanScenarios(scenarios) {
  const results = scenarios.map(scenario => {
    const { principal, annualRate, years, label } = scenario;
    const payment = calculateMonthlyPayment(principal, annualRate, years);
    const totalPaid = payment * years * 12;
    const totalInterest = totalPaid - principal;
    
    return {
      label: label,
      monthlyPayment: payment,
      totalPaid: totalPaid,
      totalInterest: totalInterest,
      principal: principal
    };
  });
  
  // Sort by total cost
  results.sort((a, b) => a.totalPaid - b.totalPaid);
  
  console.log('Loan Scenarios Ranked by Total Cost:\n');
  results.forEach((result, index) => {
    console.log(`${index + 1}. ${result.label}`);
    console.log(`   Monthly Payment: $${result.monthlyPayment.toFixed(2)}`);
    console.log(`   Total Interest: $${result.totalInterest.toFixed(2)}`);
    console.log(`   Total Paid: $${result.totalPaid.toFixed(2)}\n`);
  });
  
  return results;
}

// Compare multiple home purchase scenarios
const scenarios = [
  { principal: 280000, annualRate: 6.5, years: 30, label: '30-Year Fixed (20% down)' },
  { principal: 280000, annualRate: 6.5, years: 15, label: '15-Year Fixed (20% down)' },
  { principal: 320000, annualRate: 7.0, years: 30, label: '30-Year Fixed (10% down + PMI)' },
  { principal: 350000, annualRate: 6.0, years: 30, label: '30-Year Fixed (0% down VA)' }
];

compareLoanScenarios(scenarios);

Troubleshooting

Issue: Monthly Payment Calculation Seems Too High or Too Low

Cause: Input errors in loan amount, interest rate, or loan term.

Solution:

• Verify loan amount is correct (subtract down payment from purchase price)
• Confirm interest rate is annual percentage (e.g., enter “6.5” for 6.5%, not “0.065”)
• Check loan term is in years, not months (unless calculator specifically asks for months)
• Ensure you’re using the correct interest rate (APR, not just note rate—include points and fees)

Prevention: Double-check all inputs before relying on calculations. Review sample calculations online to confirm your results are in the expected range.

Issue: Amortization Schedule Shows Tiny Balance Remaining After Final Payment

Cause: Rounding differences in long calculations with many decimal places.

Solution:

• This is mathematically normal—final payment is often slightly adjusted
• The calculator should round the final balance to zero
• In reality, lenders adjust the final payment to account for rounding
• A few cents or dollars difference over 360 payments is negligible

Prevention: This is not an error; it’s an artifact of decimal precision limitations in calculations.

Issue: Can’t See Complete Amortization Schedule on Mobile

Cause: Long amortization schedules (30 years = 360 rows) are extensive on small screens.

Solution:

• Scroll within the results panel to view all payments
• Export to CSV and view in spreadsheet app for better mobile experience
• Rotate device to landscape orientation for wider viewing
• Use pinch-to-zoom for detailed viewing
• Consider viewing on tablet or desktop for comprehensive analysis

Prevention: For detailed analysis on mobile, use CSV export feature.

Issue: Want to Calculate Interest Savings from Extra Payments

Cause: Standard calculator may not have built-in extra payment feature.

Solution:

• Calculate loan twice: once with standard payment, once with reduced term approximating extra payments
• Use calculator’s extra payment feature if available
• Manually adjust principal in amortization schedule to see impact
• Reference code examples showing extra payment calculations
• Online extra payment calculators exist specifically for this purpose

Prevention: Use calculators explicitly designed for extra payment analysis, or export CSV and model manually in spreadsheet.

Issue: Results Don’t Match Lender’s Quote

Cause: Lender quotes may include additional fees, PMI, taxes, and insurance not in basic calculation.

Solution:

• Ensure you’re comparing apples-to-apples (principal + interest only vs. PITI)
• Ask lender for principal and interest breakdown
• Verify interest rate quoted (sometimes lenders quote APY instead of APR)
• Confirm loan term and any special provisions
• Lender may round monthly payment to nearest dollar

Prevention: Request detailed amortization schedule from lender showing all assumptions.

Issue: Calculator Doesn’t Include PMI, Taxes, or Insurance

Cause: Basic mortgage calculators focus on principal and interest only.

Solution:

• Calculate P&I using the calculator
• Add monthly tax estimate (annual property tax ÷ 12)
• Add monthly insurance (annual premium ÷ 12)
• Add PMI if down payment less than 20% (typically 0.5-1% of loan amount annually)
• Some advanced calculators include these fields—look for PITI calculators

Prevention: For complete housing payment calculations, use comprehensive mortgage calculators with tax and insurance inputs. Our calculator supports these additional fields.

Issue: Exported CSV Has Formatting Problems

Cause: Different spreadsheet programs handle CSV imports differently.

Solution:

• Open CSV in text editor to verify data structure
• Use spreadsheet’s import wizard rather than double-clicking
• Specify comma as delimiter if prompted
• Check that numbers import as numbers, not text
• Apply currency formatting after import

Prevention: Familiarize yourself with your spreadsheet application’s CSV import process.

Frequently Asked Questions

1. What’s the difference between a 15-year and 30-year mortgage?

A 15-year mortgage has higher monthly payments but dramatically lower total interest costs and builds equity faster. You’ll pay off your home in half the time and typically save over $100,000 in interest on a $300,000 loan. A 30-year mortgage has lower monthly payments, providing more budget flexibility and allowing you to invest the payment difference elsewhere. The best choice depends on your income, financial goals, and whether you prioritize monthly cash flow or long-term savings. Use our calculator to compare both scenarios with your specific numbers.

2. How much home can I afford?

Financial advisors typically recommend your monthly housing payment (including principal, interest, taxes, and insurance) not exceed 28% of gross monthly income. For example, with $6,000 monthly income, target no more than $1,680 monthly. Use our calculator to work backward—input different loan amounts and terms to find what produces a comfortable payment. Remember to factor in down payment savings, closing costs, emergency reserves, and other debts. Pair this calculator with our Interactive Savings Goal Calculator to plan your down payment savings timeline.

3. Should I make extra mortgage payments?

Extra payments reduce total interest and shorten your loan term significantly. However, consider: Do you have high-interest debt (credit cards) to pay first? Have you maximized retirement contributions (especially employer matches)? Do you have an adequate emergency fund? If yes to all, extra mortgage payments can save tens of thousands in interest. Even small extra payments (an extra $100-200 monthly) produce substantial long-term savings. Use our calculator to model specific extra payment scenarios and see the exact savings.

4. When does refinancing make sense?

Refinancing typically makes sense when: (1) Current rates are at least 0.75-1% lower than your existing rate, (2) You’ll stay in the home long enough to exceed the break-even point (months to recover closing costs through monthly savings), (3) Your credit has improved since original financing, enabling better rates, or (4) You’re shifting from adjustable to fixed-rate for payment stability. Calculate both mortgages and determine your break-even period. If you’ll stay beyond that timeframe, refinancing likely makes financial sense.

5. What’s an amortization schedule and why does it matter?

An amortization schedule is a month-by-month breakdown showing how each payment is divided between principal (paying down your loan balance) and interest (cost of borrowing). Early payments are predominantly interest—on a 30-year mortgage, your first payment might be 80% interest. This gradually reverses until final payments are nearly all principal. Understanding this helps you appreciate the value of extra principal payments (which dramatically reduce total interest) and shows why paying a mortgage for just a few extra years costs so much more in interest.

6. What’s included in my monthly mortgage payment?

Most mortgage payments include four components (PITI): Principal (paying down the loan balance), Interest (cost of borrowing), Taxes (property taxes often escrowed and paid by lender), and Insurance (homeowners insurance and PMI if applicable). Some payments also include HOA fees. A $1,500 PITI payment might break down as: $800 P&I, $350 taxes, $200 insurance, $150 PMI. Use our calculator to determine your P&I portion, then add taxes and insurance for your complete monthly obligation.

7. How does my credit score affect my mortgage rate?

Credit scores dramatically impact interest rates. Excellent credit (740+) qualifies for the best rates, while lower scores face rate premiums. A 1% rate difference on a $300,000 30-year mortgage means approximately $180/month or $65,000 over the loan life. If your credit has improved since your original mortgage, refinancing at a better rate can save substantially. Check your credit report for errors and consider delaying home purchase to improve your score if it’s below 700—the rate savings can be worth the wait.

8. What’s the benefit of a larger down payment?

Larger down payments provide multiple benefits: (1) Lower monthly payments (smaller loan amount), (2) Reduced total interest paid, (3) Potential to avoid PMI (usually required if down payment is less than 20%), (4) Better interest rates (lenders reward larger down payments with lower rates), and (5) More equity from day one, providing financial cushion if home values decline. However, don’t deplete your emergency fund—maintain 3-6 months of expenses even after down payment. Use our Interactive Savings Goal Calculator to plan your down payment savings strategy.

9. Should I pay off my mortgage early or invest the money instead?

This depends on comparing your mortgage interest rate to expected investment returns. If your mortgage rate is 6% and you can reliably earn 8-10% in investments (historical stock market average), investing provides better returns. However, mortgage payoff is guaranteed savings, while investment returns aren’t certain. Consider your risk tolerance, age (closer to retirement favors debt elimination), other debts, and emotional value of being debt-free. Many people split the difference—making some extra mortgage payments while also investing. Use our Advanced ROI & Profitability Calculator to compare returns.

10. How can I use this calculator with other Gray-wolf financial tools?

This mortgage calculator integrates perfectly with our financial planning suite. Use Interactive Savings Goal Calculator to plan your down payment savings. Use Advanced ROI & Profitability Calculator to compare real estate investment returns against alternatives. Use Investment Growth & Compound Interest Calculator to model whether paying off your mortgage or investing additional funds produces better long-term wealth. Together, these tools provide comprehensive financial planning capabilities. See our Financial Toolbox Overview for integrated planning strategies.

References

Internal Resources

• Advanced ROI & Profitability Calculator - Compare mortgage costs against investment returns
• Investment Growth & Compound Interest Calculator - Model alternative investment scenarios
• Interactive Savings Goal Calculator - Plan down payment savings strategies
• Smart Tip & Bill Split Calculator - Calculate everyday financial transactions
• Financial Toolbox Overview - Comprehensive financial planning guide

External Resources

• Consumer Financial Protection Bureau (CFPB) Mortgage Calculator - Official government mortgage resources
• Freddie Mac: Understanding Mortgages - Mortgage education from secondary market leader
• Bankrate Mortgage Guide - Comprehensive mortgage information and rate comparisons
• Investopedia: Amortization Explained - Technical details of loan amortization

Calculation Formulas

• Monthly Payment: M = P[r(1+r)^n]/[(1+r)^n-1]
  • M = Monthly payment
  • P = Principal loan amount
  • r = Monthly interest rate (annual rate ÷ 12)
  • n = Total number of payments (years × 12)
• Total Interest: (Monthly Payment × Number of Payments) - Principal
• Remaining Balance: B = P[(1+r)^n-(1+r)^p]/[(1+r)^n-1]
  • B = Remaining balance after p payments

Last updated: November 3, 2025 | Part of Gray-wolf Tools Financial Suite