# Compound interest calculator — in your browser, no upload

> Project savings growth with compound interest and regular contributions in your browser. No upload — the math runs on your device. Not financial advice.

See how savings grow over time with compound interest and regular contributions, and how much of the total is growth versus what you put in. The math runs on your device.

A compound interest calculator makes the case for starting early: because returns compound on a growing balance, the gap between contributions and final balance widens dramatically over time. Splitting the total into "what you added" versus "what it earned" makes that concrete.

Enter a starting amount, a recurring contribution, an assumed rate, and a horizon to project the balance year by year. Adjust the rate for inflation if you want the answer in today's purchasing power.

Projections use the inputs you provide and are illustrative, not financial advice — real returns vary and are not guaranteed. To work in the other direction on debt, use the Loan & mortgage calculator.

## How to

1. **Enter a starting amount.** Set your initial balance, or zero if you are starting fresh.
2. **Add contributions.** Enter a regular deposit and how often you make it.
3. **Set rate and time.** Choose an annual return rate, the compounding frequency, and the number of years.
4. **Calculate.** See the projected balance and the split between contributions and interest, computed locally.

## FAQ

### What does compounding frequency change?

How often interest is added back to the balance. More frequent compounding grows slightly faster because interest starts earning interest sooner.

### Should I use a real or nominal rate?

For a rough projection use a nominal annual return; to think in today's money, use a rate reduced by expected inflation.

### Why is the growth so back-loaded?

Compounding accelerates: the balance earning returns is largest near the end, so most of the growth appears in the later years — which is why starting early matters.

### Are my figures uploaded?

No. The projection runs in your browser tab; the amounts you enter never leave your device.


## Related tools

- [Loan & mortgage](https://www.safepaper.app/finance/loan-amortization)
- [Invoice / receipt](https://www.safepaper.app/finance/invoice-generator)
- [Statement redactor](https://www.safepaper.app/finance/statement-redactor)

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