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No Professional Financial Advice: The tools and calculators on this site are provided for educational and informational purposes only. They are not professional financial, legal, tax, or investment advice. The results are mathematical projections based on your inputs and do not guarantee future results.
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Compound Interest Calculator
See exactly how your investment grows over time with compound interest. Year-by-year chart included.
Private by design
Calculator results are estimates based on your inputs. They are useful for learning, planning, and comparison, but they are not professional advice.
Use responsibly
Finance outputs are educational projections, not investment, tax, legal, or financial advice.
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Compound interest formula
A = P × (1 + r/n)^(n×t)
- A = Final amount
- P = Principal (starting amount)
- r = Annual interest rate (decimal)
- n = Compounding frequency per year
- t = Time in years
Why compound interest is so powerful
With compound interest, you earn interest on your interest. £10,000 at 8% for 30 years grows to over £100,000 without adding a single extra pound. Einstein reportedly called it "the eighth wonder of the world."
See Real-World Compound Interest Examples
If you want examples instead of formulas, read Compound Interest Examples UK: From £100 to £1 Million. It walks through delayed starts, ISA and pension wrappers, fee drag, and the long-term cost of leaving money in cash.
Compounding frequency comparison
For a 10,000 investment at 10% for 10 years: annual compounding = 25,937 / monthly = 27,070 / daily = 27,179. The difference between monthly and daily is small; what matters most is the rate and duration.
Related guides and tools
- Compound Interest Examples UK — Real examples covering fees, pensions, delayed starts, and ISAs
- Investment Growth Calculator — Model longer-term portfolio growth with additional assumptions
- The 5% Rule Rent vs Buy Guide — Useful when comparing investing a deposit versus putting it into property