Formula & assumptions
Growth is calculated month by month, adding the selected monthly contribution before or after each month’s interest. A fractional-period rate makes the contribution schedule consistent with annual, quarterly or daily compounding assumptions. The entered annual rate is nominal, not an already effective annual yield. Rates stay constant throughout the projection; no country-specific interest tax is deducted.
Worked example
At 0% interest, an initial 10,000 plus 100 each month for 10 years becomes 22,000. With interest, the result also includes earnings on earlier interest and contributions.
How to use this calculator
- Enter the starting balance and monthly contribution.
- Set a nominal annual rate, whole-year period and compounding frequency.
- Choose contribution timing, then compare the final balance with your total contributions.
Frequently asked questions
Does compounding frequency matter?
For the same nominal annual rate, more frequent compounding increases the effective annual yield. Do not enter an effective yield as if it were nominal.
Are market returns guaranteed?
No. This is a constant-rate mathematical projection, not a forecast or financial product recommendation.
Are tax, fees or inflation deducted?
No. Those depend on the account and jurisdiction and must be assessed separately.