Compound Interest Tools

Simple vs Compound Calculator

Simple vs Compound Interest Calculator

Compare how much extra growth compound interest may produce versus simple interest over the same time period.

Inputs

Your calculation

£
%

£
£
%

% annually
%
%

Outputs

Results

Enter your numbers and click calculate.

Final balance
£0.00
Total contributions
£0.00
Withdrawals: £0.00
Interest earned
£0.00
Tax/fees: £0.00

Year-by-year table

A yearly summary of balance, contributions and interest.

YearDepositsWithdrawalsInterestTax / feesEnd balance

What if I start 5 years earlier?

Calculate to see the comparison.

Simple vs compound interest

Calculate to see the comparison.

Excel formula

Copy a formula based on your current inputs.

=FV(...)

Growth chart

Visualise how your balance builds from the starting amount plus accrued interest.

Yearly chart

Month-by-month table

Click a year to expand the monthly breakdown.

Guide

How this calculator works

Simple interest is calculated only on the original amount. Compound interest adds earned interest back into the balance, so the next period earns interest on a larger amount. The results panel includes a simple versus compound comparison automatically.

You can still change every input: currency, interest rate, years and months, compounding frequency, contribution timing, inflation and tax or fees. Use the share URL button to save a pre-filled version of the result.

FAQ

Simple vs Compound Interest Calculator FAQ

Simple interest uses the original principal only. Compound interest uses the principal plus previously earned interest.

Each compounding period adds interest to the balance, which means future interest is calculated on a larger amount.

Yes. You can include deposits, although the simple comparison is an estimate while the compound result is calculated month by month.