How much could you build by adding money every month? Enter your starting balance, monthly contribution, time frame, and assumed annual return to see how much you put in and how much it could grow.
Estimated result
Enter your assumptions and select Calculate.
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- Total money contributed
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- Estimated gain or loss
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Assumes the same return and contribution every month. Taxes, fees, and inflation are excluded.
Balance over time
The table shows each 12-month milestone and the final month. Dollar amounts are displayed to the nearest cent; intermediate calculations are not rounded.
| Time | Money contributed | Gain or loss | Balance |
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What if you contribute $300 a month for 10 years?
The default example starts at $0 and adds $300 at the end of each month for 120 months, assuming a 6% effective annual return. You contribute $36,000 in total. Each contribution grows for the time remaining; the final contribution has no time to earn a return yet. These are example dollar amounts, not a currency conversion from the Korean version.
Why isn't the annual rate divided by 12?
This calculator treats 6% as the total growth over one year. The equivalent monthly rate is about 0.4868%. Dividing 6% by 12 instead gives 0.5% per month, which compounds to about 6.17% over a year. If your account quotes a nominal annual rate, convert it to an effective annual rate before using this calculator.
Does contributing at the start of the month make a difference?
With a positive return, contributing at the start of the month gives each deposit one extra month of growth. At 0%, the timing makes no difference. With a negative return, earlier contributions are exposed to one more month of losses.
Will a savings account or investment earn this amount?
Not necessarily. This is a constant-return illustration. Actual investments fluctuate, and savings accounts may use daily balances, different crediting schedules, or changing rates. Fees and taxes can also reduce what you keep.
Only calculating a starting balance?
Set the monthly contribution to $0, or use our lump-sum compound growth calculator to find the number of periods needed to reach a target. Our guide to doubling your money and the Rule of 72 explains how the rate affects the time required.
Results illustrate your assumptions and do not predict or guarantee investment returns. The calculator does not send your entered amounts to a calculation server or store them.