Mortgage Calculator
Mortgage Calculator
The Mortgage Calculator helps anyone considering purchasing a home or refinancing understand their monthly payment structure. Buying a home is one of the largest financial decisions most people make, and understanding PITI (Principal, Interest, Taxes, Insurance) is essential for determining how much house you can afford.
A mortgage is a loan secured by real estate where the borrower makes regular payments over a set term. Understanding how the four components of PITI work together is crucial. Principal reduces your loan balance, interest is the cost of borrowing, taxes fund local services, and insurance protects your property. When the down payment is under 20 percent, PMI protects the lender against default.
The interest rate significantly affects both your monthly payment and total interest. A difference of just one percentage point on a $300,000, 30-year mortgage can mean over $60,000 in additional interest costs. Similarly, a larger down payment reduces your loan amount and may eliminate PMI.
Enter the purchase price of the home and your down payment. A 20 percent down payment eliminates PMI. Enter the annual interest rate, which depends on your credit score, loan type, and market conditions. Enter the loan term, typically 15 or 30 years.
If you have estimates for annual property taxes and homeowner's insurance, enter these amounts. Property tax rates vary by location from under 0.5 percent to over 2 percent of property value. If your down payment is under 20 percent, enter your estimated PMI rate.
Press Calculate to see monthly P&I, total monthly payment including taxes/insurance/PMI, and total interest paid. Adjust any input to compare different scenarios such as a larger down payment or lower rate.
The monthly principal and interest payment uses the standard amortization formula:
Where P is the loan principal, i is the monthly interest rate, and N is the total number of monthly payments.
The total monthly payment adds monthly equivalents of taxes, insurance, and PMI:
Monthly payments and total interest for different loan scenarios (20% down, no taxes/insurance/PMI):
| Loan Amount | Rate | Term | Monthly P&I | Total Interest |
|---|---|---|---|---|
| $200,000 | 6.0% | 30 yr | $1,199 | $231,640 |
| $200,000 | 6.5% | 30 yr | $1,264 | $255,040 |
| $300,000 | 6.5% | 30 yr | $1,896 | $382,560 |
| $300,000 | 7.0% | 30 yr | $1,996 | $418,560 |
| $400,000 | 6.5% | 30 yr | $2,528 | $510,080 |
Shop for mortgage rates from at least three to five lenders before committing. Compare APR, which includes fees and points, not just the nominal interest rate. Consider getting quotes from banks, credit unions, online lenders, and mortgage brokers.
Consider the impact of your down payment carefully. A 20 percent down payment eliminates PMI, but if saving 20 percent delays your purchase by several years, buying sooner with a smaller down payment may make financial sense in a rising market.
A 15-year mortgage has higher payments but significantly lower total interest. A 30-year mortgage offers lower payments but much more interest over the long term. Many homeowners choose a 30-year term and make extra principal payments when possible for flexibility.
This calculator provides estimates. Actual property tax and insurance costs vary by location. PMI rates vary by lender and credit score. The calculator assumes a fixed interest rate for the entire term; adjustable-rate mortgages are not accurately modeled.
Escrow accounts may result in slightly different monthly payments. PMI cancellation when you reach 78 percent LTV is not modeled. Changes in tax assessments or insurance premiums are not included.
- What is PITI and why does it matter?
- Principal, Interest, Taxes, Insurance — the four components of your total monthly payment. Lenders use 28% front-end ratio to qualify borrowers.
- How does amortization work in early years?
- Early payments are mostly interest. For a 30-year loan at 7%, roughly 80% of early payments goes to interest. Over time the split shifts.
- Should I choose a 15-year or 30-year mortgage?
- 15-year has lower rate but higher payment, saving ~$150k+ interest. 30-year has lower payments but much more total interest.
- What is the total interest on a loan?
- On a 30-year $300k loan at 7%, total interest is ~$418k. At 6%, ~$347k. Even 1% matters enormously.
- How do extra payments affect my mortgage?
- $100 extra/month on $300k at 7% saves ~$63k and cuts 5 years off a 30-year loan.
- Consumer Financial Protection Bureau. "What Is a Mortgage?" consumerfinance.gov.
- Fannie Mae. "Mortgage Payment Calculator." fanniemae.com.
- Freddie Mac. "Understanding Mortgage Payments." freddiemac.com.
- U.S. Department of Housing and Urban Development. "Buying a Home." hud.gov.
- Investopedia. "Mortgage: Definition, Types, and How They Work." investopedia.com.
Last updated: May 12, 2026