Mortgage Calculator
Buying a home or refinancing starts with one question: what will it actually cost each month? Our mortgage calculator answers that in seconds. Enter the property price, your deposit, the interest rate and the term, and you will see your monthly repayment, the total interest you will pay over the life of the loan, and your loan-to-value (LTV) band — all worked out instantly.
Mortgage Calculator
Work out your monthly mortgage payment, total interest and loan-to-value from your property price and deposit.
How a Mortgage Payment Is Actually Worked Out
A repayment mortgage blends two things into a single monthly figure: interest on the outstanding balance, and a slice of capital that gradually pays the loan down. Early in the mortgage, most of your payment is interest, because the balance is at its highest. As the years pass, more of each payment chips away at the capital, and the interest portion shrinks. This is why a 25-year mortgage costs noticeably more in total interest than a 20-year one at the same rate, even though the monthly payment on the shorter term is higher.
Interest-only mortgages work differently. You only pay the interest each month, so your payment is lower — but the full capital balance is still owed at the end of the term. Lenders will want to see a credible repayment strategy, such as an ISA, investment portfolio, or planned sale of the property, before agreeing to interest-only terms.
Why Your Deposit Size Changes Your Rate
Loan-to-value, or LTV, is simply your mortgage as a percentage of the property price. A £270,000 mortgage on a £300,000 home is a 90% LTV deal. Lenders price risk in bands, typically 60%, 75%, 80%, 85%, 90% and 95%. Drop from a 90% to an 85% LTV and you will usually unlock a noticeably better rate — sometimes half a percentage point or more — because the lender is exposed to less risk if house prices fall. If you are close to a lower band, it is often worth delaying a purchase by a few months to save the extra deposit, since the rate saving over 25 years can dwarf a short delay.
A Worked Example
Take a £280,000 property with a £28,000 deposit (10%), a rate of 4.6%, over 25 years. The £252,000 loan works out at roughly £1,415 a month on a repayment basis, with total interest of around £172,500 over the full term — more than half the amount borrowed. Switch the same numbers to interest-only and the monthly payment drops to around £966, but the entire £252,000 is still owed at the end, and total interest paid is lower only because no capital is repaid along the way — the comparison is not like-for-like.
What the Calculator Does Not Include
This tool estimates the core mortgage cost, but a full budget should also factor in product/arrangement fees (often £500–£1,999), valuation fees, buildings insurance, and — for buyers rather than remortgagers — Stamp Duty Land Tax and legal costs. Use our Stamp Duty Calculator alongside this one to get the complete picture of what you will need on completion day.
How Rates Are Set, and Why They Move
Mortgage rates broadly track two things: the Bank of England base rate for tracker and variable products, and wholesale “swap rates” for fixed deals — essentially what it costs lenders to borrow money for a fixed period on the money markets. When the market expects the Bank of England to raise or cut rates in future, swap rates move in anticipation, often before the base rate itself actually changes. This is why fixed mortgage rates can shift even between Bank of England meetings, and why the rate you are quoted today may not be available in a few weeks’ time. It is one of the reasons many buyers and remortgagers choose to secure a rate as soon as they are ready, rather than waiting in the hope of a better deal appearing later.
It is also worth remembering that the rate you are offered is not purely about the base rate — your own credit profile, LTV band, income type and the specific lender’s current appetite for new business all play a part. Two people applying on the same day, for similar-sized loans, can be offered noticeably different rates depending on these individual factors, which is exactly why shopping around, or using a whole-of-market mortgage broker, tends to produce a better outcome than accepting the first quote you receive.
Frequently Asked Questions
Is this calculator accurate for my actual mortgage offer?
It gives a close estimate based on standard capital-and-interest maths. Your actual lender may round payments slightly differently or apply a different day-count convention, but the figures here will typically be within a few pounds a month of a real illustration.
Should I choose a shorter or longer term?
A shorter term means higher monthly payments but far less total interest. A longer term eases monthly cash flow but costs more overall. Many buyers choose the longest term they are comfortable with initially, then use our Overpayment Calculator to pay it down faster once their finances allow.
What counts as a good mortgage rate in 2026?
Rates move with the Bank of England base rate and swap rates, so “good” is relative to the market at the time. Comparing at least three lenders — and checking both the rate and the fee — is the best way to judge a deal, rather than relying on a fixed benchmark.
Does the deposit include Stamp Duty and fees?
No. Your deposit is separate from Stamp Duty, legal fees, survey costs and moving costs. Budget for these as additional cash you will need on top of your deposit.