Compound interest calculator with regular contributions
Estimate a future balance from a starting amount, fixed annual rate and regular deposits. Use matching contribution and compounding frequencies here: mixed schedules can miscount deposits or interest.
Runs in your browser — your input is not uploaded to ToolsNow.
Sets formatting only.
This projects growth using the rate and contributions you enter. It leaves out tax, fees and inflation.
Actual returns can change, so the final balance is an estimate, not a promise.
How to use
- Enter the starting amount, rate and years. Use a nominal annual percentage rate, held constant for the scenario.
- Set matching frequencies. Choose the same option for Contribute and Compound, even with a zero contribution. Deposits are added at the end of each period.
- Compare money added and interest. €1,000 at 5% for two years, with both frequencies Annually and no deposits, gives €1,102.50: €1,000 contributed and €102.50 interest.
- Open the year-by-year table. Each row shows deposits, interest and the closing balance for that year; the starting amount is separate from the row’s Added figure.
Questions
What changes when I add regular deposits?
With matching monthly frequencies, each deposit is added after that month’s interest. For example, €1,000 to start plus €100 per month for two years at 0% ends at €3,400, all from contributions.
What is the effective annual rate?
It expresses one year of compounding as a single percentage, assuming a constant nominal rate. At 12% nominal with monthly compounding, it is about 12.683%. It is a rate calculation, not the percentage growth of a balance that also receives deposits.
Can I mix weekly deposits and monthly compounding?
The controls allow it, but mixed-frequency balances and contribution totals are not dependable in the current calculator. Use matching frequencies for an illustrative scenario, and use the account’s actual schedule when checking a statement.
Does this include tax, fees or inflation?
No. It also assumes the entered rate continues throughout the term. The result is a fixed-rate illustration rather than a forecast of investment returns or future spending power.
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