Compound Interest Calculator
See how savings and regular deposits grow with monthly compound interest.
Your result
Updates as you type. Based on 2025/26 UK figures where relevant.
How this is worked out
Interest is added monthly and then earns interest itself. Regular monthly deposits are added at the end of each month.
Tips
- Pay off high-interest debt before saving beyond a basic emergency fund.
- Use your £20,000 ISA allowance each year where you can – it doesn't roll over.
- Check whether your savings rate beats inflation; if not, your money is losing value.
Guides for this calculator
- How to Calculate Compound Interest in the UK: Step-by-Step Guide
- Compound Interest: Common Mistakes, Tips and FAQs
More savings and loans calculators
Frequently asked questions
How does the compound Interest Calculator work?
Interest is added monthly and then earns interest itself. Regular monthly deposits are added at the end of each month.
Are returns guaranteed?
No. Savings and investment projections are illustrations based on the rate you enter. Investments can go down as well as up.
What rate should I use for investments?
Many people test a cautious 4–5% and a more optimistic 6–7% to see a range of outcomes.
Is my savings interest taxed?
Basic-rate taxpayers have a £1,000 Personal Savings Allowance, higher-rate taxpayers £500. Interest inside an ISA is tax-free.
This calculator gives an estimate for general information. It isn't financial, tax, legal or medical advice. Check official figures on GOV.UK or NHS.uk, or speak to a qualified adviser.