Compound interest calculator
See how compound interest grows your money over time, with monthly top-ups and your choice of yearly, monthly or daily compounding. Change any figure to compare scenarios side by side.
Frequently asked questions
What is compound interest?
It's interest earned on your interest as well as your original money, so savings grow faster the longer you leave them.
How does compounding frequency change things?
More frequent compounding (daily vs yearly) adds a little more, because interest is added to your balance sooner. The difference is small at typical savings rates.
How is this different from simple interest?
Simple interest only ever pays on your original amount. Compound interest pays on the growing balance, which is why it pulls ahead over time.
Related tools
- Net worth calculator — Free UK net worth calculator.
- Savings goal calculator — Free savings goal calculator.
- Savings interest calculator — Free savings interest calculator with compound interest and monthly top-ups.
- ISA allowance calculator — Free ISA allowance calculator for 2026/27.
- Personal Savings Allowance calculator — Free Personal Savings Allowance calculator.
- FSCS limit checker — Free FSCS limit checker.
- Premium Bonds calculator — Free Premium Bonds calculator.
- All free UK finance tools
- Back to Oinkly