Mortgage Payment Calculator

What you actually pay

Amortisation schedule

Where each payment goes, month by month. Early payments are almost entirely interest — the balance barely moves for the first decade, which is why the curve starts flat.

The table above groups the 360 months into 30. The amortisation schedule prints every one of them, with the split between interest and principal.

Worked example

$400,000 at 6.5% over 30 years is $2,528/mo in principal and interest, and $510,178 of interest across the term — more than the house itself. The same loan over 15 years costs $3,485/mo but only $227,200 in interest.

How to work it out yourself

1. 1.Take the loan amount — the purchase price less your deposit, not the purchase price.
2. 2.Divide the annual rate by 100 and then by 12 for the monthly rate, and multiply the term in years by 12 for the number of payments.
3. 3.Payment is principal × rate ÷ (1 − (1 + rate)^−payments). Every fixed-rate loan uses this same formula.
4. 4.Multiply the payment by the number of payments and subtract the principal to see the total interest.
5. 5.Add property tax, insurance and any PMI on top before deciding what you can afford.

Monthly payment on $400,000 over 30 years by rate

Principal and interest only. Each quarter point is roughly $65 a month and $23,000 across the term.

The formula

1. Number of payments30 * 12
2. Monthly principal & interest300000 * 0.0054167 / (1 - pow(1 + 0.0054167, -360))
3. Total paid over the term1896.2041 * 360
4. Total interest682633.47 - 300000
5. Loan against value300000 / 500000 * 100
6. PMI applies
7. PMI a month0 * 300000 * 0.55 / 100 / 12
8. Property tax a month6000 / 12
9. Insurance a month1800 / 12
10. Full monthly payment (PITI)1896.2041 + 500 + 150 + 0 + 0
11. Above principal and interest2546.2041 / 1896.2041 * 100 - 100
12. Balance at which PMI must stop0.78 * 500000
13. PMI drops off after
14. PMI paid before it drops0 * 0
15. Paid off on2026-10-02 + 360 * 30.436875
16. Property tax a month in ten years6000 * pow(1 + 3 / 100, 10) / 12
17. Insurance a month in ten years1800 * pow(1 + 3 / 100, 10) / 12
18. Full payment in ten years1896.2041 + 671.95819 + 201.58746 + 0
19. Half payment, every two weeks1896.2041 / 2
20. What that adds up to a month1896.2041 * 13 / 12
21. Months to payoff paying biweeklylog(1896.2041 * 13 / 12 / (1896.2041 * 13 / 12 - 300000 * 0.0054167)) / log(1 + 0.0054167)
22. Years cut off by paying biweekly(360 - 289.83073) / 12
23. Interest saved paying biweekly382633.47 - (1896.2041 * 13 / 12 * 289.83073 - 300000)

Source: CFPB — understanding loan options and amortization, Federal Reserve — consumer mortgage information, US CFPB — when private mortgage insurance must be cancelled (Homeowners Protection Act)

Questions people actually ask

What is missing from this number?

Property tax, homeowners insurance, HOA dues and PMI. Lenders quote PITI, which commonly runs 25–40% above the principal-and-interest figure. Budget from PITI, not from this line alone.

Why does a small rate change move the payment so much?

Interest compounds over 360 payments. On a $400,000 30-year loan, each 0.25% of rate is roughly $65/mo and about $23,000 over the term.

Does paying extra principal shorten the term?

Yes, and disproportionately early on. In year one of a 6.5% 30-year loan, about 86% of each payment is interest, so an extra $200/mo applied to principal removes roughly 5 years from the schedule.

Will my mortgage payment stay the same?

The principal and interest will, on a fixed-rate loan — that part is contractual and never moves. Everything else does: property tax follows assessments, insurance has risen faster than inflation in most states, and both are collected through escrow. At 3% a year the escrow half of the payment above is a third larger in ten years while the loan half is unchanged.

When does PMI come off?

Automatically when the balance reaches 78% of the original purchase price on schedule, and on request at 80% — that is the Homeowners Protection Act, and it applies to most conforming loans. Paying extra principal reaches the threshold sooner, and an appraisal showing the home has risen in value can get you there sooner still. FHA loans are different: mortgage insurance on most of them lasts the life of the loan.

Fifteen years or thirty?

Fifteen costs roughly half again as much a month and less than half the interest, and it usually carries a rate about half a point lower. Thirty keeps the payment low and leaves the difference available for anything else — including a retirement account, which is the argument for it. The comparison above runs the same loan both ways.

Are discount points worth buying?

Each point costs 1% of the loan and typically cuts the rate by about a quarter point. Divide the cost by the monthly saving to get the break-even in months — usually four to seven years. Buy points only if you are confident you will neither move nor refinance before then.

Related

• Compound Interest CalculatorFuture value of a starting balance plus monthly contributions, separating what you put in from what the interest earned.
• Mortgage Payoff CalculatorWhen a mortgage clears if you pay extra each month, how many years that cuts off the term, and what the interest saved comes to.
• Property Tax CalculatorProperty tax from a home value, with the two things most calculators skip: the assessment ratio, and the exemption that comes off the value rather than the tax.
• Loan Payment CalculatorMonthly payment and total interest on any fixed-rate instalment loan — car, personal or student.
• Savings Goal CalculatorThe monthly contribution needed to reach a target by a date, given what you have saved already.
• Rent Affordability CalculatorWhat rent your income supports under both the 30% rule and the stricter 28/36 debt-to-income test.

Worked out already

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