How to Use the Mortgage Payment & Amortization Calculator
This mortgage calculator estimates your monthly home loan payment and builds a full amortization schedule so you can see how each payment splits between principal and interest over the life of the loan. Enter your home price, down payment, interest rate, and loan term to instantly see your monthly principal-and-interest payment, your total interest cost, and the complete month-by-month breakdown of how your balance shrinks.
The four inputs are: (1) Home Price—the purchase price of the property; (2) Down Payment—the cash you pay upfront, which is subtracted from the price to determine your loan amount; (3) Interest Rate—your annual mortgage rate as a percentage; and (4) Loan Term—the length of the loan in years, most commonly 15 or 30. Your loan amount (the principal) is simply the home price minus your down payment.
Your results show four key figures: the monthly principal-and-interest payment, the loan amount financed, the total interest paid across the full term, and the total of all payments combined. The amortization table below reveals a crucial pattern—in the early years, most of each payment goes to interest, while in the later years it shifts almost entirely to principal. Remember this calculator covers principal and interest only; budget separately for property taxes, homeowners insurance, and PMI.
Monthly Payment & Total Interest by Loan Term ($320,000 loan at 6.5% APR)
This comparison shows how choosing a shorter term raises your monthly payment but slashes the total interest you pay over the life of the loan.
| Loan Term | Monthly Payment (P&I) | Total Interest Paid | Total Paid |
|---|---|---|---|
| 15 years | $2,787 | $181,600 | $501,600 |
| 20 years | $2,385 | $252,500 | $572,500 |
| 30 years | $2,023 | $408,200 | $728,200 |
Figures are principal and interest only and assume a fixed rate. Moving from a 30-year to a 15-year term on this loan saves about $226,600 in interest.
Impact of Down Payment ($400,000 home, 6.5% APR, 30 years)
A larger down payment lowers your loan amount, your monthly payment, your total interest, and helps you avoid PMI once you reach 20% down.
| Down Payment | % Down | Loan Amount | Monthly Payment | PMI Required? |
|---|---|---|---|---|
| $14,000 | 3.5% | $386,000 | $2,440 | Yes |
| $40,000 | 10% | $360,000 | $2,275 | Yes |
| $80,000 | 20% | $320,000 | $2,023 | No |
| $120,000 | 30% | $280,000 | $1,770 | No |
Reaching 20% down eliminates PMI, which can save $150–$400 per month on a loan of this size. Payments shown are principal and interest only.
How a Payment Splits Over Time ($320,000 loan, 6.5%, 30 years)
Every payment is the same $2,023, but the share going to principal grows each year while the interest share falls—this is the heart of amortization.
| Payment # | Toward Interest | Toward Principal | Remaining Balance |
|---|---|---|---|
| Month 1 | $1,733 | $290 | $319,710 |
| Month 120 (year 10) | $1,470 | $553 | $270,600 |
| Month 240 (year 20) | $938 | $1,085 | $171,100 |
| Month 360 (final) | $11 | $2,012 | $0 |
It takes roughly 19 years on a 30-year loan before more of your payment goes to principal than to interest. Extra principal payments accelerate this dramatically.
Pro Tips
- Aim for a 20% down payment to avoid PMI—on a $400,000 home that means $80,000 down, and skipping PMI can save $150–$400 every month until you would otherwise reach 20% equity.
- Compare a 15-year and a 30-year term in the calculator above—the shorter term costs more monthly but can save you well over $200,000 in interest on a typical loan if you can afford the higher payment.
- Add an extra principal payment when you can—because early payments are mostly interest, even $200/month extra early in the loan can cut years off the term and tens of thousands off total interest.
- Remember to budget beyond principal and interest—property taxes, homeowners insurance, HOA dues, and PMI can add 25%–40% on top of the payment this calculator shows.
Common Mistakes to Avoid
Treating the P&I payment as your full housing cost
This calculator shows principal and interest only. Your real monthly outlay also includes property taxes, homeowners insurance, and often PMI—commonly adding 25%–40% on top of the number shown here.
Entering the home price as the loan amount
Your loan is the home price minus your down payment. This calculator subtracts the down payment for you, so enter the full purchase price in the Home Price field and your cash down separately.
Choosing the longest term just for a lower payment
A 30-year term has the lowest monthly payment but by far the highest total interest. Always look at the total interest figure, not just the monthly payment, before locking in a term.
Using an advertised rate instead of your actual quoted rate
Headline rates assume excellent credit and specific conditions. Get a personalized rate quote and enter that into the calculator—a difference of even 0.5% meaningfully changes your payment and total cost.
Frequently Asked Questions
What is a mortgage amortization schedule?
A mortgage amortization schedule is a table showing every monthly payment across the life of your loan, split into how much goes toward interest and how much reduces your principal balance. Early in a 30-year mortgage, the vast majority of each payment covers interest; over time, that ratio shifts toward principal. For a $320,000 loan at 6.5% over 30 years, your first payment applies roughly $1,733 to interest and only $290 to principal, while your final payments are almost entirely principal. This calculator builds the full schedule so you can see exactly when you cross the halfway point on equity.
How much should my down payment be?
A 20% down payment is the classic benchmark because it lets you avoid Private Mortgage Insurance (PMI), which typically costs 0.5%–1.5% of the loan amount annually. On a $400,000 home, 20% means $80,000 down and an $320,000 loan. Many buyers put down less—FHA loans allow as little as 3.5%, and conventional loans can go to 3%—but a smaller down payment means a larger loan, higher monthly payments, more total interest, and usually PMI until you reach 20% equity. Enter different down payment amounts above to see the impact instantly.
Does this calculator include property tax, insurance, and PMI?
No—this calculator shows the principal and interest (P&I) portion of your payment only, which is the core mortgage math. Your actual monthly housing cost also includes property taxes (roughly 0.5%–2.5% of home value per year depending on your state), homeowners insurance ($1,000–$3,000/year typically), and PMI if your down payment is under 20%. These are often bundled into your payment through an escrow account. To estimate your true monthly cost, add roughly 1/12 of your annual tax + insurance + PMI to the P&I figure this calculator produces.
How does the loan term affect my mortgage?
A shorter term means higher monthly payments but dramatically less total interest. On a $320,000 loan at 6.5%, a 30-year term costs about $2,023/month with roughly $408,000 in total interest, while a 15-year term costs about $2,787/month but only about $181,000 in total interest—a savings of over $225,000. The trade-off is affordability: the 15-year payment is about $764 higher each month. Use the term field above to compare 15, 20, and 30-year scenarios for your own numbers.
What is the difference between interest rate and APR on a mortgage?
The interest rate is the raw cost of borrowing your principal, while the APR (Annual Percentage Rate) folds in lender fees, points, and certain closing costs to reflect the loan's true annual cost. A mortgage might advertise a 6.25% interest rate but carry a 6.45% APR once origination fees and points are included. This calculator uses the interest rate for the payment math (which is how lenders compute your actual monthly payment), but you should compare loan offers using APR to understand the full cost.
How can I pay off my mortgage faster?
Making extra principal payments is the most effective strategy. Adding just $200/month to a $320,000 loan at 6.5% over 30 years can shave off roughly 5 years and save over $90,000 in interest. Other approaches include making biweekly payments (which results in 13 full payments per year instead of 12), refinancing to a shorter term when rates drop, or applying windfalls like tax refunds directly to principal. Because early payments are mostly interest, extra principal early in the loan has the biggest impact on total interest saved.
When does it make sense to refinance my mortgage?
Refinancing generally makes sense when you can lower your interest rate by at least 0.5%–1%, and you plan to stay in the home long enough to recoup the closing costs (typically 2%–5% of the loan amount). For example, refinancing a $320,000 loan from 7.5% to 6.5% could lower your payment by about $215/month; if closing costs are $8,000, your break-even point is about 37 months. Refinancing also lets you switch from a 30-year to a 15-year term or convert an adjustable-rate mortgage to a fixed rate.
What credit score do I need for the best mortgage rate?
A credit score of 760 or higher typically qualifies you for the lowest available mortgage rates. Scores between 700–759 still get competitive rates, while scores in the 620–699 range face progressively higher rates and may require a larger down payment. The difference is substantial: a borrower with a 760 score might get 6.25% while a 660-score borrower gets 7.25% on the same loan—on a $320,000 30-year mortgage, that 1% gap adds about $215/month and over $77,000 in total interest. Check and improve your credit before applying.
References & Resources
- Consumer Financial Protection Bureau — Owning a Home
Official government guides on mortgages, closing costs, and comparing loan offers by APR.
- Federal Reserve — Selected Interest Rates
Authoritative source for current benchmark interest rate data that influences mortgage rates.
- U.S. Department of Housing and Urban Development — Buying a Home
HUD resources on FHA loans, down payment assistance, and the home-buying process.
- Fannie Mae — Homebuyer Education
Educational materials on mortgage qualification, PMI, and understanding amortization.