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Mortgage Payment Calculator

Work out the monthly payment on a repayment mortgage, and see how much of the term goes on interest.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
The loan amount, after your deposit.

This is the purchase price less the deposit, plus any fees you are adding to the loan. Fees added to the borrowing accrue interest for the whole term, which is usually a worse deal than paying them up front.

The annual rate you have been quoted.

Use the actual rate on the offer, not an advertised headline. On a fixed-rate deal, remember the payment shown here holds only for the fixed period — model the reversion rate separately.

Length of the mortgage in years.

A longer term cuts the monthly payment and raises the total interest, often dramatically. The breakdown shows the total, which is the number worth comparing between terms.

Monthly payment

Needs your Interest rate (% per year)

This page does not assume a price. Enter yours and the answer appears here.

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Standard amortisation: M = P·r(1+r)ⁿ / ((1+r)ⁿ − 1), where r is the monthly rate and n the number of payments
  • Rate is a user input with no default assumed from any market — enter the rate you have been quoted

Inputs used

Amount borrowed
250000
Interest rate (% per year)
Term (years)
25
Final resultNaN

What this calculation does not cover

  • Principal and interest only. Property taxes, buildings insurance, mortgage protection and any service charge are additional.
  • Assumes the rate holds for the whole term. A fixed-rate deal reverts, and the payment after reversion can be very different.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations2
  1. Standard amortisation: M = P·r(1+r)ⁿ / ((1+r)ⁿ − 1), where r is the monthly rate and n the number of payments
  2. Rate is a user input with no default assumed from any market — enter the rate you have been quoted
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

How to calculate mortgage payment in 4 steps

  1. Amount borrowedThe loan amount, after your deposit.
  2. Interest rate (% per year)The annual rate you have been quoted.
  3. Term (years)Length of the mortgage in years.
  4. Monthly paymentThe tool computes the monthly payment from those figures and shows the formula, its sources, and a confidence rating alongside it.

Frequently asked questions

Why does a longer term cost so much more overall?
Because interest accrues on the outstanding balance for longer. On 250,000 at 5%, a 25-year term repays about 438,000 and a 35-year term about 528,000 — the monthly payment falls by roughly 200 and the total rises by about 90,000. The breakdown shows the total for exactly this comparison.
Why is so much of an early payment interest?
Because interest is charged on the balance, and at the start the balance is nearly the whole loan. The breakdown shows the interest portion of the first payment; on a typical 25-year mortgage it is around 70% of it. That share falls slowly at first and then quickly toward the end.
Does this include taxes and insurance?
No. This is principal and interest only. Property tax, buildings insurance, any mortgage protection and service or ground charges are on top, and in some markets they add 25-40% to what actually leaves your account each month.
What happens when my fixed rate ends?
The loan reverts to the lender's variable rate, which is usually higher. Run this calculator twice — once at the fixed rate for the fixed period, and once at a realistic reversion rate on the balance that will remain — to see the payment you would actually face.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.