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Published 04 March 2024
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Mortgage Interest Rate Calculator

Use our mortgage interest rate calculator to estimate how much your repayments could change if interest rates rise or fall, and to compare different rates and terms.

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Many or all of the products and brands we promote and feature including our ‘Partner Spotlights’ are from our partners who compensate us. However, this does not influence our editorial opinion found in articles, reviews and our ‘Best’ tables. Our opinion is our own. Read more on our methodology here.

Mortgage interest rate calculator

How will a rise or fall in interest rates affect my mortgage?

Different interest rates and mortgage terms can change your monthly mortgage repayments and the amount in interest you repay. Use this calculator to compare different mortgage scenarios.

Scenario 1
Scenario 2
Monthly Mortgage Payment
£584.59
£416.67
Mortgage Term – Interest Paid
£75,377.01
£125,000
Mortgage Term – Total Paid
£175,377.01
£225,000

Your mortgage debt over time

Balance remaining in undefined

This calculator is designed to give you a guide on mortgage costs. It also makes certain assumptions to be able to provide calculations over a longer period that will not be reflected in your own mortgage. The actual mortgage you obtain will depend on a number of factors that are specific to your own personal and financial circumstances.

Partner Spotlight

Compare Mortgages

Tell us what you’re looking for and see current UK mortgages available, including rates, repayments and product information. Continue online to our partner L&C for fee-free mortgage help and advice.

Loan Type

Showing 3 of 50 results

Lender Name Initial Rate Monthly Repayments Product Fees Annual Cost

HSBC
4.83% initial rate
Fixed to 30/09/29
then 6.99% (variable)

Max LTV 90%
£1,293.14
Monthly Repayments
£999.00
Product Fees
6.29% APRC
£15,647.48
Annual Cost
6.29% APRC Max LTV 90%
Fees and Charges
Booking fee £0
Arrangement fee £999
Other fees £0
Valuation fee £0
Cashback £ 350
Flexibility & Other info
Overpayments allowed? 10% p/a
Early Repayment Charge 5% reducing to 1% until 30/09/29
Exit fee £0
Basic legals Payable
Fees and Charges   Flexibility & Other info
Booking fee £0 Overpayments allowed? 10% p/a
Arrangement fee £999 Early Repayment Charge 5% reducing to 1% until 30/09/29
Other fees £ 0 Exit fee £0
Valuation fee £0 Basic legals Payable
Cashback £ 350
Representative example A mortgage of £225,000 payable over 25 years, initially on a fixed rate for 5 years at 4.83% and then on a variable rate of 6.99% for the remaining 20 years would require 60 payments of £1,293 and 240 payments of £1,539. The total amount payable would be £447,589 made up of the loan amount plus interest (£221,940) and fees (£649). The overall cost for comparison is 6.3% APRC representative.

Barclays
4.85% initial rate
Fixed to 30/09/29
then 8.74% (variable)

Max LTV 90%
£1,295.74
Monthly Repayments
£999.00
Product Fees
7.48% APRC
£15,748.68
Annual Cost
7.48% APRC Max LTV 90%
Fees and Charges
Booking fee £0
Arrangement fee £999
Other fees £0
Valuation fee £0
Cashback £ 0
Flexibility & Other info
Overpayments allowed? 10% p/a
Early Repayment Charge 4% until 30/09/29
Exit fee £80
Basic legals Payable
Fees and Charges   Flexibility & Other info
Booking fee £0 Overpayments allowed? 10% p/a
Arrangement fee £999 Early Repayment Charge 4% until 30/09/29
Other fees £ 0 Exit fee £80
Valuation fee £0 Basic legals Payable
Cashback £ 0
Representative example A mortgage of £225,000 payable over 25 years, initially on a fixed rate for 5 years at 4.85% and then on a variable rate of 8.74% for the remaining 20 years would require 60 payments of £1,295 and 240 payments of £1,755. The total amount payable would be £499,899 made up of the loan amount plus interest (£273,900) and fees (£999). The overall cost for comparison is 7.5% APRC representative.

Clydesdale
4.85% initial rate
Fixed to 31/10/29
then 9.24% (variable)

Max LTV 90%
£1,295.74
Monthly Repayments
£1,680.00
Product Fees
7.83% APRC
£15,884.88
Annual Cost
7.83% APRC Max LTV 90%
Fees and Charges
Booking fee £0
Arrangement fee £1499
Other fees £0
Valuation fee £181
Cashback £ 0
Flexibility & Other info
Overpayments allowed? 10% p/a
Early Repayment Charge 5% reducing to 2% until 31/10/29
Exit fee £99
Basic legals Payable
Fees and Charges   Flexibility & Other info
Booking fee £0 Overpayments allowed? 10% p/a
Arrangement fee £1499 Early Repayment Charge 5% reducing to 2% until 31/10/29
Other fees £ 0 Exit fee £99
Valuation fee £181 Basic legals Payable
Cashback £ 0
Representative example A mortgage of £225,000 payable over 25 years, initially on a fixed rate for 5 years at 4.85% and then on a variable rate of 9.24% for the remaining 20 years would require 60 payments of £1,295 and 240 payments of £1,819. The total amount payable would be £515,940 made up of the loan amount plus interest (£289,260) and fees (£1,680). The overall cost for comparison is 7.8% APRC representative.

Think carefully before securing other debts against your home.  You home may be repossessed if you do not keep up repayments on a loan or any other debt secured on it.

Important Information:
This mortgage product comparison service is provided by L&C Mortgages. Information is updated up to twice daily from L&C’s whole of market mortgage database, however some products may be excluded such as those only available directly with a lender or specialist products. Products are initially shown in order of initial rate but can be reordered. By selecting to Continue Online you will introduced to L&C Mortgages and their qualified advisors a Nerdwallet brings you this mortgage rate comparison as a guide. Information does not constitute advice or recommendation. Rates should be considered with all fee’s and charges. Mortgage suitability is specific to your own personal and financial circumstances.

Need Advice?

NerdWallet has partnered with L&C, the UK's leading fee free mortgage broker, to offer you expert advice

Call L&C on:
0808 292 0841

How to calculate mortgage interest 

A simple way to calculate the interest on your mortgage is to:

  1. First, find your outstanding mortgage balance and current mortgage interest rate
  2. Then divide your current mortgage interest rate by 100, giving you a decimal figure.
  3. Now multiply your outstanding mortgage amount by the decimal figure.
  4. And finally, divide the number you get by 12.

The number you have calculated is the amount of interest you’ll pay on your next monthly mortgage repayment. 

For example, let’s say your outstanding mortgage loan amount is £150,000 and your interest rate is 5%.

To work out how much interest you’ll pay in the coming month, the calculation is:

So your next monthly mortgage repayment will include £625 in mortgage interest. Note that if you have a capital repayment mortgage, where some of the original mortgage is also paid back each month, your overall monthly mortgage repayment will be higher to account for this too. 

With the alternative of an interest-only mortgage, you just pay the interest on your mortgage every month. However, you’ll need a plan in place to pay off your original loan amount when your mortgage ends.

» MORE: Mortgage repayment calculator

Calculating how much interest you pay on a mortgage overall

Working out how much interest you’d pay on a mortgage in total is more difficult to calculate manually yourself. This is because your outstanding mortgage decreases every month with a typical capital repayment mortgage. It’s also unlikely that you’ll pay the same interest rate for the entire duration of your mortgage. 

However, a mortgage lender will still give you an estimate of the total interest payable on a given mortgage deal based on certain assumptions. Our mortgage interest calculator can give you a similar idea of how much interest you will pay.

Using the NerdWallet mortgage interest rate calculator 

Our mortgage interest rate calculator can be used to compare the interest and repayments payable across different interest rates and mortgage terms. It can also be used to get an idea of how mortgage repayments may change if interest rates were to rise or fall. 

The calculator is intended as a guide only and relies on certain assumptions. It is based on your mortgage rate remaining the same for the duration of your mortgage, which isn’t likely to happen. Always speak to your current mortgage lender for details of how interest rate changes might affect your mortgage repayments before comparing deals from other lenders or brokers.

Are mortgage interest rates calculated daily or monthly?

This depends on your lender and particular mortgage, so you’d need to check with them directly to confirm either way. A daily interest mortgage sees the amount of interest you’re charged recalculated each day based on your outstanding mortgage debt. So if you overpay on your mortgage, you may pay less interest due to your outstanding mortgage coming down quicker than if you have a monthly interest mortgage, where the interest you pay is calculated once a month. 

What happens if interest rates rise or fall?

If interest rates rise or fall and you have a fixed-rate mortgage deal, your mortgage repayments should stay the same for as long as you’re within your initial fixed-rate period. However, if you have a tracker mortgage or are paying your lender’s standard variable rate (SVR), there’s a good chance your monthly repayments will change if interest rates change.

Mortgage repayments on these variable rate mortgages can become more expensive if interest rates rise and cheaper if they fall – though interest rate fluctuations are not always passed on immediately to borrowers. Mortgage rates generally can be influenced by a wide range of factors, including changes in the Bank of England base rate or because of varying levels of competition between lenders.

» MORE: See current mortgage rates

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