Savings growth
Enter starting amount, monthly contribution, APR and term.
Optional – leave blank or 0 for none
Compound interest calculator
Future value of a savings pot with monthly contributions. Choose start or end of month deposits.
Estimates only. Interest assumed monthly and constant; fees/tax not included.
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How to use the Compound Interest Calculator
- Enter your initial amount and optional monthly contribution.
- Set the interest rate (APR %) and the term in years.
- Choose deposit timing: start of month or end of month.
- Select Calculate to see the future value, total contributions, interest earned, and a yearly breakdown.
Examples
- £5,000 start, £200/month, 5% APR, 10 years, deposits at end of month → shows future value with monthly compounding.
- £0 start, £300/month, 7% APR, 15 years, deposits at start of month → higher balance due to earlier compounding.
Formula
For monthly compounding with regular deposits:
Future value =
P (1 + r)n + PMT [(1 + r)n − 1] / r
where P = initial amount, PMT = monthly contribution, r = APR/12, n = years × 12.
Tips
- Monthly compounding grows faster than annual when contributions are regular.
- Start-of-month deposits earn slightly more than end-of-month.
- Results are nominal (before fees and inflation). For real returns, subtract your inflation assumption.
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AER / APR Converter · Savings Goal (time to target) · Mortgage Overpayment — time & interest saved · Percentage Calculator
Quick FAQ
Do you support monthly contributions?
Yes — add a monthly amount and choose deposit timing (start or end of month).
Is the interest rate APR or AER?
Enter the APR. If you have an AER, convert it first with the AER / APR converter.
Can I see a yearly breakdown?
After calculating, the table shows each year’s start balance, contributions, interest, and end balance.