DIY Cost Tools
Future Value Calculator
Project the future value of a starting amount plus equal end-of-period contributions using a chosen annual rate, term, and compounding frequency.
Contributions are assumed to occur at the end of each selected period. Enter nonnegative amounts, a term from 0.01 to 200 years, and a rate from −99% to 1,000%.
How to use the future value calculator
Enter a starting balance, an optional equal contribution, the annual rate you want to test, the number of years, and a matching contribution and compounding frequency. The result separates the money contributed from the mathematical growth estimate.
Future value formulas
The starting amount grows as P(1 + i)N. End-of-period contributions grow as PMT × [((1 + i)N − 1) ÷ i]. Here i is the annual rate divided by the number of periods per year, and N is the total number of periods. At a zero rate, the contribution portion is simply PMT × N.
Worked example
A $5,000 starting amount with $100 added monthly for 10 years at a 6% nominal annual rate compounded monthly grows to approximately $25,484.92. Total contributions are $17,000, so the modeled growth is approximately $8,484.92.
What the result can show
The calculator illustrates the combined effect of time, regular contributions, and compounding. Compare several rates and time horizons instead of treating one output as a forecast. Increasing contributions can often have a more predictable effect than assuming a higher return.
Important limitations
This educational projection assumes a constant nominal rate and equal contributions at the end of every period. It excludes taxes, fees, inflation, market losses, contribution limits, withdrawals, changing rates, and timing variations. Actual investments can lose value. This is not financial, investment, tax, or legal advice.
Frequently asked questions
Are contributions made at the beginning or end of each period?
The calculator assumes end-of-period contributions. Beginning-of-period deposits would have one additional period of growth.
What happens when the rate is zero?
The future value equals the starting amount plus all contributions.
Can I use a negative rate?
Yes. A negative rate models decline, provided the periodic growth factor remains positive.
Is the result guaranteed?
No. It is a mathematical scenario based on your inputs, not a prediction or guarantee.
Reference and review
Reviewed October 3, 2026. The default output, zero-rate case, negative-rate boundary, contribution timing, and invalid inputs were checked before publication. For additional investor education, see the U.S. Securities and Exchange Commission’s Investor.gov compound-interest resource.