Runs locally in your browser
Compound Interest Calculator
Project a balance with compound interest, yearly contributions, and yearly, quarterly, monthly, or daily compounding in this tab.
- Final balance
- 21538.99
- Total interest
- 10538.99
Enter principal, annual rate, years, and an optional yearly contribution when you are modelling savings, not a one-off store discount.
Each compounding period updates in the browser. The projection is not sent to a bank API.
How to use
- Fill principal, annual rate percent, years, and yearly contribution.
- Pick yearly, quarterly, monthly, or daily compounding.
- Read final balance, total interest, and the year-by-year path.
How it works
Each period multiplies the balance by one plus the period rate, then adds the contribution for that period. Contributions are the yearly amount split across compounding periods.
Total interest is final balance minus principal minus contributions over the years. This is a projection, not advice.
Examples
Starter savings
10,000 at 7 percent for 10 years with 100 per year, compounded monthly, grows past a simple annual credit.
Frequency check
The same rate compounded daily ends slightly above yearly compounding because interest meets the balance more often.
FAQ
Are contributions added at the start or end of a period?
They are added after interest in each compounding period, split from the yearly contribution field.
Is the rate nominal or effective?
You enter a nominal annual percent. The tool divides it by the number of periods per year.
Does this include inflation or fees?
No. It is a clean compound projection from the fields on the page.
Is the forecast uploaded?
No. Compounding stays in this browser tab.
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