How the calculation works
The annual rate is divided by 12 and interest is added every month, with your deposit paid in at the end of each month. Results are before tax and fees; inflation reduces what the final balance will buy.
Compound interest calculator
- Methodology & sources
- Runs in your browser
Work out how much your savings or investments could grow with regular monthly deposits and compound interest.
Final balance
£109,333
- Total paid in
- £58,000
- Interest earned
- £51,333
Interest compounded monthly, deposits at the end of each month, before tax and fees.
| Paid in | Interest | |
|---|---|---|
| Year 1 | £12,400.00 | £567.39 |
| Year 2 | £14,800.00 | £1,286.60 |
| Year 3 | £17,200.00 | £2,165.39 |
| Year 4 | £19,600.00 | £3,211.93 |
| Year 5 | £22,000.00 | £4,434.80 |
| Year 6 | £24,400.00 | £5,843.03 |
| Year 7 | £26,800.00 | £7,446.09 |
| Year 8 | £29,200.00 | £9,253.96 |
| Year 9 | £31,600.00 | £11,277.11 |
| Year 10 | £34,000.00 | £13,526.55 |
| Year 11 | £36,400.00 | £16,013.87 |
| Year 12 | £38,800.00 | £18,751.23 |
| Year 13 | £41,200.00 | £21,751.44 |
| Year 14 | £43,600.00 | £25,027.92 |
| Year 15 | £46,000.00 | £28,594.83 |
| Year 16 | £48,400.00 | £32,467.01 |
| Year 17 | £50,800.00 | £36,660.09 |
| Year 18 | £53,200.00 | £41,190.49 |
| Year 19 | £55,600.00 | £46,075.46 |
| Year 20 | £58,000.00 | £51,333.14 |
Final balance
Frequently asked questions
How does compound interest work?
Interest is added to your balance and then earns interest itself, so growth speeds up over time. The longer the money is invested, the bigger the effect.
How much will £10,000 grow with £200 a month at 5%?
After 20 years, compounded monthly, the balance would be about £109,333: £58,000 paid in and £51,333 of interest.
Is interest on savings taxed?
Interest is covered by the Personal Savings Allowance (£1,000 for basic-rate taxpayers, £500 for higher-rate, none for additional-rate). Interest and gains inside an ISA are tax-free, up to the £20,000 annual ISA allowance.