Compound Interest Calculator
Calculate how your savings grow over time with compound interest. See yearly breakdowns and visualise your wealth building.
Compound Interest Calculator
Your figures
Result
Final Amount
£17,240
£1,000.00 with £100.00 a month at 5% a year, compounded monthly, grows to £17,239.94 after 10 years. £4,239.94 of that is interest.
Assumes the rate stays the same, each contribution is paid in at the start of its compounding period, and there are no fees or tax.
- Final Amount
- £17,239.94
- Total Contributions
- £13,000.00
- Total Interest Earned
- £4,239.94
- Effective Return
- 32.61%
Your balance over time
£, at the end of each year
Year by year
| Year | Paid in to date | Interest that year | Balance |
|---|---|---|---|
| 0 | £1,000.00 | £0.00 | £1,000.00 |
| 1 | £2,200.00 | £84.16 | £2,284.16 |
| 2 | £3,400.00 | £149.86 | £3,634.03 |
| 3 | £4,600.00 | £218.93 | £5,052.95 |
| 4 | £5,800.00 | £291.52 | £6,544.47 |
Compound interest is often called the eighth wonder of the world — and for good reason. Unlike simple interest, which only earns returns on your initial deposit, compound interest earns returns on your returns.
How It Works
The formula behind compound interest is A = P(1 + r/n)^(nt), where P is your principal, r is the annual rate, n is the compounding frequency, and t is time in years.
The more frequently your interest compounds, the faster your money grows. Monthly compounding outperforms annual compounding because each month's interest gets added to the balance before the next month's calculation.
When to Use This Calculator
- Planning long-term savings goals (retirement, house deposit, education)
- Comparing savings accounts with different compounding frequencies
- Understanding the true cost of delaying your investments
- Calculating the impact of regular monthly contributions
Tips for Maximising Returns
Start as early as possible — time is the most powerful variable in the compound interest formula. Even small monthly contributions can grow significantly over decades. A £100 monthly contribution at 7% annual return grows to over £120,000 in 30 years.