Calculate monthly payments, view amortization schedules, and compare loan scenarios side-by-side.
The Mortgage Calculator estimates your monthly payment, total interest, and full amortization schedule from the loan amount, interest rate, and term — and lets you compare scenarios side by side to see what you can afford.
Take a £225,000 loan at 5.5% over 25 years. The monthly payment is £1,381.70 — and that figure, on its own, hides the three numbers that actually change decisions.
The total. £1,381.70 across 300 payments is £414,509, of which £189,509 is interest. You pay for the house roughly 1.84 times. That isn't a scandal, it's what borrowing for a quarter of a century costs — but nobody in the transaction has much incentive to say it out loud.
Where the first payment goes. Of that £1,381.70, £1,031.25 is interest and only £350.45 reduces the loan. Interest is charged on what you still owe, and at the start you owe everything. Follow the amortisation table forward: after five years you've paid £82,902 and cleared just £24,139 of the debt. The crossover, where more of each payment goes to principal than interest, lands at month 150 — exactly halfway. If there's a real chance you'll move within five years, you will have built almost no equity through repayments, which is a different bet from the one most people think they're making.
What an overpayment buys. Because every extra pound comes off the balance, and the balance generates the interest, overpayments compound in your favour for the whole remaining term. An extra £100 a month on that loan clears it in about 21 years 9 months instead of 25 — over three years early, saving roughly £29,000 in interest for £26,100 paid in. Check your lender's terms first: many fixed deals cap overpayments at 10% of the balance a year and charge fees beyond it.
The same loan over 30 years costs £1,277.53 a month — £104 cheaper, which is the number an affordability conversation will focus on. It also costs £234,909 in interest instead of £189,509. The longer term costs about £45,400 more to save £104 a month.
That's not automatically wrong. A lower committed payment is real breathing room, and a 30-year term you can comfortably overpay may well beat a 25-year term that leaves you with nothing spare. It should just be a decision made with the £45,400 in view rather than one you drift into.
It models a fixed rate held to term. It knows nothing about tracker or variable rates, offset accounts, early repayment charges, private mortgage insurance, service charges, ground rent, stamp duty, survey and legal fees, or what a lender will actually offer once they've seen your paperwork. Property tax and insurance can be entered so the monthly figure reflects a real outgoing, but those are your estimates, not quotes. Use it to compare scenarios against each other — that's what it's good at.
The Unit Converter handles the square-feet-to-square-metres problem every property listing creates, which matters because price per square metre is one of the few objective ways to compare two homes. The Age Calculator answers how old you'll be when the term ends — a subtraction a surprising number of people run only after signing. Both are covered together in the buying a home guide, with the full worked example.
It is based on your loan principal, interest rate, and term using the standard amortization formula. Each payment covers interest on the remaining balance plus principal; the calculator also shows the full payoff schedule.
Amortization is how a loan is paid off over time. Early payments go mostly to interest and later ones mostly to principal. The calculator shows this breakdown month by month.
The core calculation covers principal and interest. Property tax, homeowners insurance, and PMI vary by location and lender, so treat the result as your base payment and add those separately.
No — it is an estimate for planning only. Confirm exact figures with your lender before making decisions.