Free calculatorTax year 2026/27
Mortgage calculator
Monthly payment, total interest, and total repayable on a repayment mortgage.
The calculator
How the mortgage calculator works
Enter the amount you want to borrow, the interest rate and the term, and the calculator works out your monthly repayment, the total interest you will pay over the life of the loan and the total amount repayable. It assumes a standard capital-and-interest (repayment) mortgage where the balance reduces each month.
Use it to compare deals, sense-check affordability before you apply, or see how overpaying or a shorter term changes the total cost. Remember that lenders also assess your income, outgoings and credit history, so the figure they offer may differ from the illustration here.
What the monthly figure leaves out
This estimates capital and interest on the loan. The cost of owning is larger: stamp duty on the way in, legal and survey fees, buildings insurance, service charge and ground rent on a leasehold, and maintenance on anything. Lenders assess affordability against a stressed rate rather than the one you are offered, which is why an approval can come in below what the arithmetic suggests.
Term, rate and the trade-off between them
Extending the term reduces the monthly payment and increases the total interest substantially. Shortening it does the reverse. Overpaying early is worth far more than overpaying late, because interest is charged on the balance — though most fixed deals cap annual overpayments, and the cap is worth checking before planning around it.
For a buy-to-let, remember the interest is no longer deducted from rental profit but relieved at the basic rate, which changes the arithmetic of a higher-rate landlord's return considerably.
Frequently asked
Is the monthly payment fixed?+
The calculator assumes a fixed rate for the whole term. In practice most mortgages are fixed for an initial period and then move to a variable rate, so your payment can change when the deal ends.
Does a shorter term really save money?+
Yes — a shorter term means higher monthly payments but far less total interest. Try a few terms in the calculator to see the difference.
Why did the bank offer me less than this suggests?+
Affordability is assessed against a stressed interest rate rather than the rate you are quoted, and against your commitments and outgoings rather than income alone. The payment being affordable today is not the test being applied.
Is it better to overpay or shorten the term?+
Financially they are close, but overpaying keeps flexibility — a shorter term is a contractual commitment to the higher payment. Either way, early overpayments are worth much more than late ones. Check the annual overpayment cap on a fixed deal first.
Beyond the tools
An estimate is a starting point, not a plan.
Bring us the number you just worked out and we will tell you what it means for your position — and what to do about it.
Or call 07480 281548