zacdaddytools
Estimate how UK savings or investments could grow with compound interest and regular monthly contributions.
See how regular saving and compounding add up.
Monthly contributions are added at the end of each month.
An estimate based on a steady rate and regular deposits.
Estimated balance after 10 years
£55,290.66
Your money grows by £15,290.66 in interest
Total deposited
£40,000.00
Interest earned
£15,290.66
Year-by-year estimate
| Year | Total contributed | Interest that year | Estimated balance |
|---|---|---|---|
| 1 | £13,000.00 | £581.33 | £13,581.33 |
| 2 | £16,000.00 | £764.56 | £17,345.89 |
| 3 | £19,000.00 | £957.16 | £21,303.06 |
| 4 | £22,000.00 | £1,159.62 | £25,462.67 |
| 5 | £25,000.00 | £1,372.43 | £29,835.11 |
| 6 | £28,000.00 | £1,596.13 | £34,431.24 |
| 7 | £31,000.00 | £1,831.28 | £39,262.52 |
| 8 | £34,000.00 | £2,078.46 | £44,340.98 |
| 9 | £37,000.00 | £2,338.28 | £49,679.27 |
| 10 | £40,000.00 | £2,611.40 | £55,290.66 |
Interest is applied before each end-of-month contribution. Results are estimates and do not include tax, fees, inflation or changes to the rate.
Estimate only. Actual rates can change and tax, inflation or fees are not included.
Enter a starting balance, an optional monthly contribution, an annual interest rate and a duration from one to one hundred years. You can compare annual, half-yearly, quarterly, monthly or daily compounding and view a year-by-year estimate.
The result separates the money contributed from the interest generated. This makes it easier to see how regular saving and time contribute to the final balance rather than focusing only on the headline total.
With compound interest, previously earned interest remains in the balance and can itself earn interest. Simple interest, by contrast, is calculated only on the original balance. The standard lump-sum formula is A = P(1 + r/n)^(nt), where n is the number of compounding periods each year.
More frequent compounding can produce a slightly higher result when the quoted nominal annual rate is unchanged. This calculator converts the selected compounding schedule into an equivalent monthly growth rate before applying each monthly contribution.
£1,000 at 5% for one year becomes £1,050.
A second year at 5% adds £52.50, producing £1,102.50 before any fees, tax or withdrawals.
Regular contributions increase the money that can earn future interest. The calculator assumes each contribution is made at the end of the month, after that month’s interest has been applied. The year-by-year table shows total contributions, interest earned in that year and the estimated balance.
Real savings and investments may have variable rates, fees, tax, contribution timing and investment losses. Inflation also changes what a future balance can buy. Use the output to compare assumptions, not as a guaranteed return or personal financial advice.
For a broader explanation of borrowing and saving rates, see MoneyHelper interest-rate guidance.
FAQs
Yes. Enter a monthly contribution and it is added at the end of every month throughout the selected term.
Simple interest is calculated only on the original balance. Compound interest is calculated on the balance including previously earned interest.
The projected balance equals the starting balance plus all monthly contributions, with no interest added.
It controls how often interest is added to the balance. At the same nominal rate, more frequent compounding can slightly increase growth.
No. The tool is a gross mathematical projection and does not deduct fees or tax or adjust the result for inflation.