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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.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Monthly payment

1461.48 per month

High confidence

Arithmetic on the figures you enter. Not a lending decision, not an offer, and not regulated financial advice — speak to a qualified adviser before acting on it.

Total repaid over the term
438442.53
Total interest
188442.53
Interest as a share of the loan
75.38 %
First payment going to interest
1041.67

Running these inputs gives 1461 per month as the monthly payment. Note that amount borrowed sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Add the equipment this sizes

This result is a specification — 1,461.475 per month — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

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 — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • 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

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.

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.