Mortgage Calculator
Free instant mortgage calculator: Calculate monthly payments, total interest & amortization schedule. See your true borrowing cost today.
Enter Values
Fill in the fields and press Calculate to see instant results.
What is a Mortgage Calculator?
A Mortgage Calculator is a financial tool that helps homebuyers and homeowners determine monthly payments, total interest, and the true cost of homeownership. Whether you're buying your first home, refinancing, or evaluating different loan options, this calculator provides instant clarity on your mortgage obligations.
Understanding your mortgage payments is crucial for financial planning. This calculator removes uncertainty and helps you make informed decisions about home purchases and financing options.
When to Use This Calculator
- Home purchase planning: Determine affordability and monthly payment obligations
- Comparing loan options: Test different down payments, rates, and terms
- Refinancing decisions: See if refinancing saves money compared to your current mortgage
- Budget planning: Ensure mortgage payments fit within your monthly expenses
- Evaluating different properties: Compare affordability across different price points
- Understanding amortization: See how much principal vs interest you pay each month
- Calculating total interest: Understand the true cost of borrowing over 15, 20, or 30 years
Mortgage Payment Formula
Mortgages use the standard amortization formula to calculate equal monthly payments:
M = P × [r(1+r)^n] / [(1+r)^n - 1]
Where: M = Monthly Payment (P&I), P = Principal (Home Price - Down Payment), r = Monthly Interest Rate (Annual ÷ 12), n = Total Payments (Years × 12)
Key Variables Explained
Home Price: The purchase price of the property you're buying.
Down Payment: The amount you pay upfront. Typically 3-20% of home price. Larger down payments reduce monthly payments and eliminate PMI.
Interest Rate: The annual cost of borrowing. Varies by credit score, market conditions, and lender. Typically 3-8%.
Loan Term: Duration of the mortgage. Common terms: 15, 20, or 30 years. Longer terms mean lower payments but higher total interest.
Property Tax: Annual tax on the property. Varies by location. Typically 0.5-2% of home value annually.
Home Insurance: Annual insurance cost. Typically $800-$2,000 depending on home value and location.
Step-by-Step Calculation Guide
- Determine home price: Identify the property you're interested in or your target price range.
- Calculate down payment: Decide what percentage (3-20%) you can afford to put down.
- Calculate loan principal: Home Price - Down Payment = Loan Amount.
- Research interest rates: Check current rates from multiple lenders based on your credit score.
- Choose loan term: Select 15, 20, or 30 years based on affordability and total cost preferences.
- Convert annual rate to monthly: Divide interest rate by 12 and by 100.
- Calculate total payments: Multiply years by 12.
- Apply the formula: Use M = P × [r(1+r)^n] / [(1+r)^n - 1].
- Add property tax and insurance: Divide annual amounts by 12 and add to monthly payment.
- Verify affordability: Ensure total housing cost is less than 28% of gross income.
Worked Examples
Example 1: First-Time Homebuyer
Given Inputs
| Input | Value |
|---|---|
| Home Price | $300,000 |
| Down Payment | $60,000 (20%) |
| Interest Rate | 6.5% |
| Loan Term | 30 years |
Calculation Steps
- Calculate loan principal= $300,000 - $60,000 = $240,000
- Convert annual rate to monthly= 6.5% ÷ 12 = 0.541% or 0.00541667
- Calculate total payments= 30 years × 12 = 360 payments
- Apply amortization formula= M = 240,000 × [0.00541667(1.00541667)^360] / [(1.00541667)^360 - 1]
- Monthly P&I payment= $1,516.96
- Total paid over 30 years= $1,516.96 × 360 = $546,105.60
- Total interest paid= $546,105.60 - $240,000 = $306,105.60
Results
Monthly Payment (P&I)
$1,516.96
Total Interest
$306,105.60
Total Amount Paid
$546,105.60
Example 2: 15-Year vs 30-Year Comparison
Given Inputs
| Input | Value |
|---|---|
| Home Price | $350,000 |
| Down Payment | $70,000 (20%) |
| Interest Rate | 6% |
| Loan Terms | 15 years vs 30 years |
Calculation Steps
- Loan principal= $350,000 - $70,000 = $280,000
- 15-year monthly payment= $2,108.02
- 15-year total interest= $99,444.36
- 30-year monthly payment= $1,679.14
- 30-year total interest= $243,686.40
- Monthly payment difference= $2,108.02 - $1,679.14 = $428.88
- Total interest difference= $243,686.40 - $99,444.36 = $144,242.04
Results
15-Year: $2,108.02/month
$99,444.36 total interest
30-Year: $1,679.14/month
$243,686.40 total interest
Trade-off
Pay $428.88 more/month but save $144,242 in interest
Example 3: Impact of Down Payment
Given Inputs
| Input | Value |
|---|---|
| Home Price | $400,000 |
| Interest Rate | 6.5% |
| Loan Term | 30 years |
| Down Payments | 5% vs 10% vs 20% |
Calculation Steps
- 5% down ($20,000): Loan amount= $380,000
- 5% down: Monthly payment= $2,408.76
- 10% down ($40,000): Loan amount= $360,000
- 10% down: Monthly payment= $2,281.40
- 20% down ($80,000): Loan amount= $320,000
- 20% down: Monthly payment= $2,026.13
- Monthly savings (5% to 20%)= $2,408.76 - $2,026.13 = $382.63
Results
5% Down: $2,408.76/month
Requires PMI (~$200-300/month)
10% Down: $2,281.40/month
Requires PMI (~$100-150/month)
20% Down: $2,026.13/month
No PMI required
Example 4: Impact of Interest Rate
Given Inputs
| Input | Value |
|---|---|
| Home Price | $300,000 |
| Down Payment | $60,000 (20%) |
| Loan Term | 30 years |
| Interest Rates | 5% vs 6.5% vs 8% |
Calculation Steps
- At 5% interest: Monthly payment= $1,288.37
- At 5% interest: Total interest= $223,412.80
- At 6.5% interest: Monthly payment= $1,516.96
- At 6.5% interest: Total interest= $306,105.60
- At 8% interest: Monthly payment= $1,763.28
- At 8% interest: Total interest= $394,780.80
- Monthly difference (5% to 8%)= $1,763.28 - $1,288.37 = $474.91
Results
5% Rate: $1,288.37/month
$223,412.80 total interest
6.5% Rate: $1,516.96/month
$306,105.60 total interest
8% Rate: $1,763.28/month
$394,780.80 total interest
Example 5: Total Housing Cost (PITI)
Given Inputs
| Input | Value |
|---|---|
| Home Price | $350,000 |
| Down Payment | $70,000 (20%) |
| Interest Rate | 6.5% |
| Property Tax (annual) | $3,500 |
| Home Insurance (annual) | $1,200 |
Calculation Steps
- Loan principal= $350,000 - $70,000 = $280,000
- Monthly P&I payment= $1,773.46
- Monthly property tax= $3,500 ÷ 12 = $291.67
- Monthly home insurance= $1,200 ÷ 12 = $100.00
- Total monthly PITI= $1,773.46 + $291.67 + $100.00 = $2,165.13
- Gross income needed (28% rule)= $2,165.13 ÷ 0.28 = $7,732.61/month or $92,791/year
- Gross income needed (36% rule)= $2,165.13 ÷ 0.36 = $6,014.25/month or $72,171/year
Results
Monthly P&I
$1,773.46
Monthly PITI (with tax & insurance)
$2,165.13
Recommended Annual Income
$72,171 - $92,791
Real-World Applications
Home Purchase Planning
Determine affordability and monthly payment obligations before making an offer on a home.
Comparing Loan Options
Test different down payments, rates, and terms to find the best mortgage structure for your situation.
Refinancing Decisions
Evaluate whether refinancing at a lower rate will save money compared to your current mortgage.
Budget Planning
Ensure mortgage payments fit within your monthly budget and financial goals.
Property Comparison
Compare affordability across different properties and price points in your target market.
Understanding Amortization
See how much principal vs interest you pay each month and how it changes over time.
Common Mistakes to Avoid
❌ Forgetting Property Tax and Insurance
The principal-and-interest payment is only part of total housing cost. Ignoring taxes and insurance underestimates true affordability needs.
✓ Solution: Add property tax and insurance estimates to get the true total monthly housing payment (PITI).
❌ Ignoring PMI Costs
Down payments below 20% require PMI, adding $100-300+ to monthly payments.
✓ Solution: Factor PMI into affordability calculations. Plan to reach 20% equity to eliminate it.
❌ Overextending Your Budget
Buying the maximum you're approved for leaves no room for emergencies or other expenses.
✓ Solution: Use the 28/36 rule and ensure housing costs don't exceed 28% of gross income.
❌ Not Shopping Around for Rates
Different lenders offer different rates. Even 0.5% difference saves tens of thousands over 30 years.
✓ Solution: Get quotes from at least 3-5 lenders before deciding.
❌ Choosing Too Long a Term
While 30-year mortgages have lower payments, they cost nearly double in interest compared to 15-year mortgages.
✓ Solution: Choose the shortest term you can afford to minimize total interest.
Tips and Best Practices
- Improve your credit score: Higher scores qualify for lower rates, saving thousands over the life of the loan.
- Save for a larger down payment: 20% down eliminates PMI and reduces monthly payments significantly.
- Get pre-approved: Know your budget before house hunting to avoid falling in love with unaffordable properties.
- Compare APR, not just interest rate: APR includes fees and gives the true cost of borrowing.
- Consider mortgage points: Paying points upfront lowers your rate if you plan to stay long enough to recoup the cost.
- Make extra payments: Even small extra payments reduce the loan term and interest significantly.
- Lock in your rate: Once you find a good rate, lock it in to protect against rate increases.
- Plan for closing costs: Budget 2-5% of home price for closing costs, appraisal, and inspections.
Related Calculators
Frequently Asked Questions
▶How is a mortgage payment calculated?
▶What is a good mortgage interest rate?
▶15-year vs 30-year mortgage?
▶What is PMI?
▶What is an amortization schedule?
▶How much house can I afford?
▶What are mortgage points?
▶Should I refinance?
Conclusion
The Mortgage Calculator is an essential tool for anyone considering homeownership. By understanding how mortgage payments are calculated and testing different scenarios, you can make informed decisions that align with your financial goals and budget constraints.
Whether you're a first-time homebuyer, evaluating refinancing options, or comparing different properties, this calculator provides the clarity you need to make confident decisions about one of life's biggest financial commitments.
People Also Calculate
Calculators visitors commonly use alongside this one.
Down Payment
Plan your down payment savings
House Affordability
Know your max home budget first
Amortization
See your full payment schedule
Loan
Compare general loan terms
Rent vs. Buy
Is buying better than renting?