CALCULATOR · Finance

Mortgage Calculator

Mortgage payment, lifetime interest and payoff — with extra payments and a yearly schedule.

Show formula

M = P·i / (1−(1+i)^−n) over the mortgage term

Method reviewed:Standard amortization: M = P·i / (1 − (1 + i)^−n) · reviewed August 2026

Currency

Loan amount

Annual interest rate

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Term (months)

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Extra monthly payment (optional)

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Result

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Enter Loan amount and the result fills in as you type.

How it works

Enter home-loan amount, rate and term (360 months = 30 years).
Optionally add extra monthly principal.
Review payment, lifetime interest and yearly amortization.

Frequently asked questions

Are escrow, insurance and taxes included?

No — this estimates principal and interest only. Ask your lender for the full PITI payment.

Why does the yearly table stop early?

With extra payments the loan finishes sooner; the table shows the actual schedule until payoff.

What is amortization?

Paying off a loan in regular instalments, each covering that month’s interest plus part of the balance, so the debt reaches zero with the final payment. An amortization schedule, like the yearly table this calculator shows, lists how each payment splits between the two.

Why is most of my early payment interest?

Because interest is charged on the balance, and at the start the balance is the whole loan. On 300,000 at 6%, the first month’s interest is 1,500.00, so only 298.65 of the 1,798.65 payment repays the loan.

How much does one percentage point on the rate cost?

On 300,000 over 30 years, 5% means a payment of 1,610.46 and 279,767.35 of interest; 6% means 1,798.65 and 347,514.57; 7% means 1,995.91 and 418,526.69. Each point moves the payment by about 190 to 200 a month and the total interest by about 70,000.

When does refinancing make sense?

When the saving outlasts the cost of switching. Divide the costs by the monthly saving to find how many months it takes to break even; if you expect to keep the loan well beyond that, the lower rate pays. A new 30-year term restarts the schedule, so compare total interest as well as the payment.

How a mortgage payment is calculated

A repayment mortgage is an annuity: the same payment every month for the whole term, worked out so that the balance reaches zero with the last one. The formula is the one any fixed-rate loan uses, M = P × r ÷ (1 − (1 + r)^−n), with r = annual rate ÷ 12 and n = years × 12.

What sets a mortgage apart is its length. For 300,000 at 6% over 30 years, r = 0.005 and n = 360, and the payment is 1,798.65. With 360 payments, interest has three decades to add up, and in this example it comes to more than the amount borrowed.

The figure is principal and interest only. Property tax, home insurance and, where it applies, mortgage insurance are usually paid on top, and they can change from year to year even when the rate is fixed.

Where the payment goes over 30 years

Interest is charged each month on the balance still owed, so it dominates the early payments and fades as the balance falls. The yearly totals for 300,000 at 6%:

300,000 at 6% over 30 years, by year
Year	Interest paid	Principal repaid	Balance at year end
1	17,899.78	3,684.04	296,315.96
10	15,270.49	6,313.33	251,057.17
20	10,097.37	11,486.45	162,010.76
30	685.41	20,898.41	0.00

Principal overtakes interest only with payment 223, in year 19. After 20 years you still owe 162,010.76, more than half of the original loan, which is why money paid off early does far more work than money paid off late.

15 or 30 years, and paying extra

The same 300,000 at 6%, four ways:

300,000 at 6%: term and extra payments
Option	Monthly payment	Total interest	Paid off after
30 years	1,798.65	347,514.57	360 months
30 years + 100 a month	1,898.65	294,168.16	313 months
30 years + 200 a month	1,998.65	256,341.13	279 months
15 years	2,531.57	155,682.69	180 months

The 15-year term costs 732.92 more a month and saves 191,831.88 of interest. Paying 200 extra on the 30-year loan saves 91,173.43 and finishes 81 months early while keeping the lower required payment, which helps if your income varies.

Before overpaying, check your mortgage terms: some fixed-rate deals cap overpayments or charge an early-repayment fee.

Common mortgage mistakes

Budgeting on principal and interest alone. Tax, insurance and any mortgage insurance are part of the real monthly cost, and none of them is in this figure.
Comparing 15- and 30-year loans by payment only. The 30-year payment is lower, and in the table above it costs more than twice the interest.
Typing the term in years. This calculator asks for months: 30 years is 360. Typed as 30, the mortgage becomes a two-and-a-half-year loan.
Assuming a fixed payment never changes. Principal and interest on a fixed-rate loan stay the same, but tax and insurance collected with the payment are reassessed, and a variable-rate loan changes whenever its rate does.
Treating total interest as the price of the house. It is the cost of borrowing if every payment runs to the end of the term. Overpaying, refinancing or selling early all change it.

Examples

A 300,000 mortgage at 6% over 30 years: 1,798.65 a month, and 347,514.57 of interest across the full 360 payments.
Why is the total interest larger than the loan itself?: At 6% over 30 years it is. Interest accrues on the outstanding balance every month, and early payments are mostly interest — the amortization table shows the year the split crosses over.