CalculatorsMortgage calculator
Mortgage calculator
See what your estimated monthly repayment could be, based on the property price, deposit, term and interest rate you enter.
Your mortgage
Tell us about the property
20% of the property price
An assumption for the calculator, not a rate quoted or available from any lender.
Assumes a repayment mortgage: your monthly payment covers interest and pays down what you borrowed, so the balance reaches zero at the end of the term.
Estimated monthly repayment
£1,403
Over 25 years, you'd repay £240,000 of borrowing plus approximately £180,905 in interest. Early payments are mostly interest; later payments are mostly principal, as the balance you owe falls.
- Mortgage amount
- £240,000
- LTV
- 80%
- Term
- 25 years
- Total repaid
- £420,905
What if the interest rate changes?
Rates move over a mortgage's life. See how your payment would change at a different rate, entered as your own assumption, not a forecast.
A 20-year term would raise your payment by approximately £181 a month, and save approximately £40,770 in total interest, compared with 25 years.
Year-by-year amortisation
| Year | Principal repaid | Interest | Balance |
|---|---|---|---|
| 1 | £4,948.58 | £11,887.62 | £235,051.42 |
| 2 | £5,201.76 | £11,634.44 | £229,849.67 |
| 3 | £5,467.89 | £11,368.31 | £224,381.78 |
| 4 | £5,747.63 | £11,088.56 | £218,634.15 |
| 5 | £6,041.69 | £10,794.50 | £212,592.45 |
| 6 | £6,350.80 | £10,485.39 | £206,241.66 |
How it works
How mortgage repayments work
This calculator assumes a repayment mortgage, the standard type in the UK today. Each monthly payment covers two things: interest on what you currently owe, and a slice of the amount you originally borrowed. As the balance you owe falls, less of each payment goes on interest and more goes toward paying down the loan, so by the end of the term the balance reaches zero.
That's different from an interest-only mortgage, where the monthly payment covers interest alone and the full amount borrowed is still owed at the end. Interest-only mortgages are now uncommon outside specific cases such as buy-to-let, and this calculator doesn't model them.
Show the technical explanation and formula
Calcular calculates your monthly payment using the standard amortising-loan formula: payment = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the mortgage amount, r is your annual interest rate divided by 12, and n is the number of monthly payments over the term. At a 0% rate that formula divides by zero, so the calculator falls back to the simpler payment = P / n instead.
The year-by-year figures and chart aren't a rough split of that formula. Calcular runs a full month-by-month simulation: each month, interest is charged on the balance carried over, and the rest of that month's fixed payment reduces the principal, the same order real mortgage accounts use.
The standard amortising repayment-mortgage formula:
payment = P × [r(1+r)^n] / [(1+r)^n − 1]
P is the mortgage amount, r is your annual interest rate divided by 12, and n is the number of monthly payments over the term.
Loan-to-value
What LTV means
Your loan-to-value ratio, or LTV, is the percentage of the property's value you're borrowing, worked out as mortgage amount ÷ property price × 100. A £240,000 mortgage on a £300,000 property is an 80% LTV: you're borrowing 80% of the property's value and putting down the other 20% as a deposit.
Lenders generally see a lower LTV as lower risk, since a bigger deposit gives you more of a buffer if the property's value falls. That's why larger deposits are usually associated with access to cheaper mortgage deals, with the best rates typically reserved for LTVs of around 60% or lower. This calculator doesn't know what rate any lender would actually offer at your LTV. It only shows the LTV itself and calculates your payment at the rate you enter.
Interest
How interest affects your mortgage
The interest rate has a large effect on both your monthly payment and how much you pay in total, because a mortgage is typically the biggest loan most people take out and runs for decades. A couple of percentage points can change the monthly payment by hundreds of pounds, and the total interest paid over the term by tens of thousands.
This calculator assumes the rate you enter stays exactly the same for the whole term. In reality, most UK mortgages fix or discount the rate for an initial period, commonly two or five years, then move to a different rate afterwards. This calculator can't predict what that rate will be, so treat the result as what your payment would be if today's assumed rate applied for the entire mortgage, not a prediction of what you'll actually pay throughout.
Mortgage term
Mortgage term: monthly cost vs. total interest
A longer mortgage term spreads the same borrowing over more payments, which usually lowers the monthly payment but increases the total interest paid, because the balance stays higher for longer and keeps accruing interest. A shorter term raises the monthly payment but reduces the total interest, since the balance is paid down faster.
There's no single right answer. It depends on what monthly payment is comfortable for you now, set against how much you'd prefer to pay in total over the life of the mortgage. This calculator shows both, and a comparison against a nearby term, so you can weigh the trade-off with your own numbers rather than a generic rule of thumb.
Scope
What this calculator doesn't include
This is a mortgage repayment calculator, not a mortgage eligibility or affordability checker, and it deliberately stops short of several things a full picture of buying a home would need:
- Affordability and eligibility. It doesn't assess income multiples, credit history, existing debts, or whether a lender would actually approve you for this mortgage.
- Product-specific rates. It doesn't fetch or reflect any lender's actual rates, fees, or product terms. The rate you enter is your own assumption.
- Introductory or fixed-rate periods. It assumes the rate you enter applies for the whole term, when in practice many UK mortgages only fix or discount the rate for the first few years.
- Remortgaging, overpayments, and early repayment charges. It projects a mortgage paid exactly as scheduled, with no extra payments, early repayment, or switching deals partway through.
- Mortgage fees, such as arrangement, booking, valuation, and broker fees. These aren't added to the loan or the monthly payment.
- Property purchase taxes, including Stamp Duty Land Tax (England and Northern Ireland), Land Transaction Tax (Wales), and Land and Buildings Transaction Tax (Scotland). These vary by nation, price, and buyer circumstances, and aren't calculated here.
- Buildings insurance and other ongoing costs of homeownership.
- Changes in interest rates over the mortgage's actual lifetime, beyond the fixed assumption you enter.
In short: this calculator answers "what would my monthly repayment be, at this rate, over this term," not "can I afford this" or "what will buying this property actually cost me."
Worked example
£300,000 property, £60,000 deposit, 25 years, 5% interest rate
Say you're buying a £300,000 property with a £60,000 deposit (20%, an 80% LTV), on a 25-year repayment mortgage at an assumed 5% interest rate.
- Mortgage amount
- £240,000.00
- Estimated monthly repayment
- £1,403.02
- LTV
- 80%
- Total repaid over 25 years
- £420,904.83
- Total interest
- £180,904.83
At a 1 percentage point higher rate (6%), the same mortgage would cost approximately £1,546 a month, about £143 more. Over a 20-year term instead of 25, the payment would rise to about £1,584 a month but total interest would fall to about £140,135, roughly £40,770 less than over 25 years.
Good to know
What this calculator does, and its limits
What it does
Calculates the estimated monthly repayment for a repayment mortgage, using the property price, deposit, term, and interest rate you enter, and simulates the full amortisation schedule month by month so the balance, total interest, and year-by-year breakdown are accurate rather than approximated.
Assumptions
- Assumes a repayment mortgage, not interest-only: every monthly payment reduces the balance, which reaches exactly zero at the end of the term.
- Assumes the interest rate you enter is constant for the entire term, with no fixed or introductory period that later changes.
- Assumes every payment is made in full and on time, with no overpayments, missed payments, or early repayment.
- Doesn't include mortgage fees, property purchase taxes, insurance, or any other cost of buying or owning a home.
Not financial advice. This is a general information tool, not a mortgage offer, an affordability assessment, or a personal recommendation. Speak to a mortgage adviser or broker, and check MoneyHelper's guidance, before making a mortgage decision.
FAQ
Common questions
How is my mortgage payment calculated?
This calculator uses the standard amortising-loan formula for a repayment mortgage, based on the amount borrowed, your interest rate, and the term. It then runs a full month-by-month simulation to work out exactly how much of each payment is interest and how much is principal, rather than estimating the split.
What interest rate should I use?
There's no rate this calculator can tell you that you'll actually be offered; it depends on your lender, your LTV, your circumstances, and the wider market at the time. It's worth trying a few different, realistic rates, including a rate a percentage point or two higher than any deal you're currently considering, to see how sensitive your payment is to rate changes.
Are mortgage interest rates guaranteed?
No. This calculator assumes a single, constant rate for the whole term you enter, but real mortgages commonly fix or discount the rate for an initial period only, after which the rate can change. It doesn't predict what your rate will be after that point.
Does this include mortgage fees?
No. Arrangement, booking, valuation, and broker fees aren't included in the mortgage amount or the monthly payment. See "What this calculator doesn't include" for the full list of costs this calculator leaves out.
Does this include Stamp Duty or other property taxes?
No. Property purchase taxes differ between England and Northern Ireland, Scotland, and Wales, and depend on the price, the property, and buyer-specific rules, so they aren't calculated here.
What does LTV mean?
Loan-to-value is the percentage of the property's value you're borrowing: mortgage amount divided by property price. A smaller deposit means a higher LTV; a larger deposit means a lower one. Lenders generally treat a lower LTV as lower risk.
How do mortgage fees affect my payment?
This calculator doesn't add fees to the loan, so they don't appear in the monthly payment shown here. In practice, some fees can be added to the mortgage itself (increasing what you borrow and repay) or paid upfront; either way, they're a real cost worth budgeting for separately.
What mortgage term should I use?
Whatever term you're actually considering. A longer term usually means a lower monthly payment but more total interest; a shorter term means a higher payment but less total interest. This calculator shows a comparison against a nearby term so you can see that trade-off with your own numbers.
Can my mortgage payment change?
In this calculator, no: the payment is fixed for the term you enter, based on the rate you enter staying constant. In reality, if your mortgage's rate changes, for instance when a fixed or discounted period ends, or if you're on a variable rate, your actual payment can go up or down.
Does this tell me if I can afford this mortgage?
No. This calculator doesn't assess affordability, income multiples, credit history, or whether a lender would approve you. It only calculates what the monthly repayment would be for the numbers you enter.
Does this calculator estimate what a lender will offer me?
No. It doesn't fetch live mortgage products, rates, or lending criteria from any lender. The rate you enter is your own assumption, and the result is an illustration based on that assumption, not a quote.
Is this financial advice?
No. Calcular is a general information tool, not financial or mortgage advice, and nothing here should be treated as a personal recommendation or an offer of lending. For guidance specific to your situation, speak to a mortgage adviser or broker, or see MoneyHelper's free mortgage guidance.
Keep exploring
Want to see what else your money could do?
See how a deposit could grow before you buy, or what a similar loan amount would look like elsewhere.