Mortgage Repayment Calculator

Last updated: April 2026

Mortgage Details

Property value

Deposit

Deposit percentage

20.00% depositLTV: 80.00%

Mortgage term

yrs

Interest rate

Mortgage Type

Monthly overpayment

Most lenders allow up to 10% of balance per year without penalty. Check your mortgage terms.

I have a fixed rate that reverts to a higher rateCompare your initial fixed payment with the likely payment after the fixed period ends.

Monthly Payment

£1,334.00

Mortgage amount£240,000.00

LTV80.00%

Total repayable£400,200.00

Total interest£160,199.49

LTV Band Indicator

Green: under 75%Amber: 75-90%Red: over 90%

Amortisation Table

YearBalance startInterestCapitalBalance end

1£240,000£10,691£5,317£234,683

2£234,683£10,447£5,561£229,122

3£229,122£10,192£5,816£223,306

4£223,306£9,924£6,084£217,222

5£217,222£9,645£6,363£210,859

6£210,859£9,353£6,655£204,204

7£204,204£9,047£6,961£197,242

8£197,242£8,727£7,281£189,961

9£189,961£8,392£7,616£182,346

10£182,346£8,043£7,965£174,380

11£174,380£7,677£8,331£166,049

12£166,049£7,294£8,714£157,335

13£157,335£6,894£9,114£148,221

14£148,221£6,475£9,533£138,688

15£138,688£6,037£9,971£128,717

16£128,717£5,579£10,429£118,288

17£118,288£5,100£10,908£107,379

18£107,379£4,599£11,409£95,970

19£95,970£4,075£11,933£84,037

20£84,037£3,526£12,482£71,555

21£71,555£2,953£13,055£58,500

22£58,500£2,353£13,655£44,845

23£44,845£1,726£14,282£30,563

24£30,563£1,070£14,938£15,625

25£15,625£383£15,625£0

Cost of delay

Every month you delay buying: at £300,000, a 1% price increase costs £3,000more. Your deposit's purchasing power decreases as property prices rise.

Rate Comparison

RateMonthlyTotal interest

3.50%£1,201.50£120,448.86

4.00%£1,266.81£140,042.58

4.50%£1,334.00£160,199.49

5.00%£1,403.02£180,904.87

5.50%£1,473.81£202,142.78

6.00%£1,546.32£223,897.03

About this calculator

The Mortgage Repayment Calculator estimates monthly payments, total interest, and remaining balance for a repayment mortgage. It is useful for buyers comparing mortgage offers, remortgagers checking new rates, homeowners testing overpayments, and anyone searching for repayments on a specific mortgage balance such as GBP 60,000, GBP 70,000, or GBP 240,000. The calculator shows how loan amount, interest rate, term, and overpayments affect both monthly affordability and long-term cost.

Mortgage repayment formula

A repayment mortgage uses amortisation. The monthly payment is calculated so that, if the rate and term stay the same, the balance reaches zero at the end of the term. Each payment first covers interest on the current balance, with the rest reducing capital.

monthly rate = annual mortgage rate / 12
monthly repayment = principal x monthly rate / (1 - (1 + monthly rate)^(-months))
monthly interest = outstanding balance x monthly rate
capital repaid = monthly payment - monthly interest
new balance = old balance - capital repaid - overpayment

How to use the mortgage repayment calculator

Enter the mortgage amount or remaining balance.
Enter the interest rate for the mortgage deal or scenario.
Enter the remaining term in years and months.
Choose repayment or interest-only if the calculator asks.
Add regular overpayments or lump sums if relevant.
Review the monthly payment, total interest, and balance path.
Run higher-rate scenarios before committing to a mortgage or remortgage.

Worked examples

GBP 60,000 mortgage repayment

Input: GBP 60,000 over 15 years at 5%

Calculation: The calculator amortises the balance over 180 monthly payments.

Result: The result shows the estimated monthly repayment and total interest across the term.

Rate sensitivity

Input: GBP 200,000 mortgage over 25 years at 4.5% compared with 5.5%

Calculation: Both scenarios use the same balance and term but different monthly rates.

Result: The higher rate increases both monthly payment and total interest.

Overpayment check

Input: GBP 180,000 balance, 20 years left, GBP 150 monthly overpayment

Calculation: The overpayment reduces the balance faster each month.

Result: The calculator estimates interest saved and the earlier payoff date.

What affects mortgage repayments

Input	Effect	Planning note
Mortgage amount	Higher balance means higher payment	Use the actual loan, not property value
Interest rate	Higher rate raises interest and payment	Stress-test future remortgage rates
Term	Longer term lowers payment but raises total interest	Compare monthly affordability and total cost
Overpayments	Reduce balance faster	Check early repayment charge limits
Interest-only option	Lowers payment but leaves capital due	Needs a repayment plan

Monthly affordability vs long-term cost

A longer mortgage term can make the monthly payment easier, but it usually increases total interest because the loan remains outstanding for longer. This is why the best mortgage choice is not always the one with the lowest monthly payment.

Using the calculator for remortgage planning

When a fixed deal ends, use the remaining balance and remaining term rather than the original mortgage amount. Compare the current payment, product transfer options, remortgage offers, and a higher-rate stress case.

Common mortgage calculation mistakes

Using the property price instead of the mortgage balance.
Ignoring product fees when comparing deals.
Forgetting that interest rates can change after a fixed period.
Assuming overpayments are always penalty-free.
Comparing monthly payment without comparing total interest.

Financial information disclaimer

This calculator is for general mortgage planning only and is not financial advice. Mortgage offers, fees, eligibility, early repayment charges, insurance, taxes, and lender rules vary. Check lender documents or speak to a qualified adviser before making mortgage decisions.

It does not guarantee lender approval.
It may not include product fees, valuation fees, or legal costs.
It assumes the entered rate and payment structure stay as modelled.

Frequently asked questions

How are mortgage repayments calculated?

A repayment mortgage uses amortisation: each monthly payment covers interest on the balance and repays part of the capital.

What are repayments on a GBP 60,000 mortgage?

They depend on the interest rate and term. Enter GBP 60,000, the rate, and the term to estimate the monthly payment.

Does a longer term reduce my mortgage payment?

Usually yes, but it can increase total interest because the debt lasts longer.

Can I include overpayments?

Yes if the calculator supports them. Check lender limits before making large overpayments.

Is this the same as affordability?

No. This calculates repayments. Lender affordability also considers income, spending, credit commitments, and stress tests.

Related calculators

Mortgage Payoff Calculator
Mortgage Affordability Calculator
Refinance Calculator
Stamp Duty Calculator

How are mortgage repayments calculated?

Repayment mortgage payments are calculated using standard amortisation. Each monthly payment covers the interest on the outstanding balance plus a portion of the capital. In the early years, most of each payment is interest. Towards the end of the term, most is capital. The result is that your balance reduces to zero at the end of the term.

What is loan-to-value (LTV)?

LTV is the mortgage amount as a percentage of the property value. A £240,000 mortgage on a £300,000 property has an 80% LTV. Lower LTV means a larger deposit and typically unlocks better mortgage rates. Most lenders offer their best rates at 60% LTV or below.

How much can overpaying save?

Overpaying your mortgage even by a small amount can save thousands in interest and reduce your term significantly. On a £240,000 mortgage at 4.5% over 25 years, overpaying £200 per month saves approximately £26,000 in interest and reduces the term by over 5 years. Most lenders allow overpayments of up to 10% of the outstanding balance per year without penalty.

What is an interest-only mortgage?

With an interest-only mortgage, your monthly payment covers only the interest on the loan. You do not repay any capital. At the end of the term, you still owe the full original loan amount. Interest-only mortgages have lower monthly payments but require a credible repayment strategy for the capital, such as savings, investments, or selling the property.