Compound Interest Calculator
See how your money grows: compound growth with regular contributions, visualized.
Compound interest means you earn returns not just on your original money, but on all the returns already added — growth on growth. It is the single most powerful force in long-term saving.
How to use
- Enter your starting amount, monthly contribution, expected annual rate and time horizon.
- Choose how often interest compounds (monthly is the common default).
- Click "Calculate growth" — the chart shows your balance pulling away from raw contributions over time.
- Scroll the table for a year-by-year breakdown of invested vs earned.
About this tool
The chart tells the real story: early on, contributions do most of the work. Given enough years, compounding takes over and interest becomes the bigger slice.
This calculator compounds your chosen frequency and adds monthly contributions evenly across periods. Figures are projections, not promises — markets do not grow in a straight line.
Frequently asked questions
Is compound interest really that powerful?
Over long horizons, yes. At 7% annual return, money roughly doubles every 10 years — but the rate is never guaranteed, which is why this shows projections, not predictions.
Should I use monthly or yearly compounding?
Monthly matches how most savings accounts and brokerages actually compound. The difference vs yearly is small but real.
Does this account for inflation and taxes?
No — it shows nominal growth. Real purchasing power will be lower after inflation, and taxes may apply to gains.
Is my data sent anywhere?
No. Every calculation runs in your browser. Nothing you type ever leaves your device.
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