Future Value Calculator
Find the future value of a lump sum plus monthly additions at a fixed rate.
What it does
Future value is what an investment or savings balance grows to after earning returns over time. Compound growth means earnings earn their own earnings.
The tool above compounds a starting amount plus monthly additions at a fixed annual rate. It shows the future value, the total contributions, and the interest earned. Enter your numbers and read the result.
Monthly additions are assumed to be made at the end of each month. Real accounts vary with fees, taxes, and rate changes, so treat this as a projection, not a promise.
Time and regular additions are the main levers. Starting earlier and adding more usually matter more than chasing a higher rate.
How to use
- Enter the starting amount.
- Enter the monthly addition you plan to make.
- Enter the annual rate of return as a percent.
- Enter the number of years.
- Enter how often interest compounds per year, usually 12 for monthly.
- Read future value first, then contributions and interest earned.
Formula
- starting amount
- Initial balance or lump sum, in dollars.
- monthly addition
- Amount added each month, in dollars.
- annual rate
- Annual rate of return, in percent.
- years
- Number of years the money compounds.
- frequency
- Compounding times per year, often 12.
Monthly additions are assumed at month end. At a zero rate, future value is simply the start plus additions with no interest.
Worked example
Example: $5,000 start, $200 monthly, 6% per year, 10 years
Starting amount 5,000, monthly addition 200, annual rate 6 percent, years 10, compounding 12 times per year.
- Months: 10 x 12 = 120 months.
- Effective monthly rate is about 0.50 percent.
- Start of 5,000 compounds to about 9,096.98.
- Additions of 200 a month compound to about 32,775.87.
- Future value: about 41,872.85. Contributions total 29,000.00 and interest earned is 12,872.85.
- Tool shows future value $41,872.85, contributions $29,000.00, interest earned $12,872.85.
Reference table
| Years | Future value | Contributions | Interest earned |
|---|---|---|---|
| 5 | $20,698.26 | $17,000.00 | $3,698.26 |
| 10 | $41,872.85 | $29,000.00 | $12,872.85 |
| 15 | $70,434.21 | $41,000.00 | $29,434.21 |
| 20 | $108,959.20 | $53,000.00 | $55,959.20 |
Limits
- Results assume a fixed rate and fixed monthly addition with no fees or taxes.
- Actual returns vary and can be negative in some periods.
- Monthly additions are assumed at month end; timing changes results slightly.
- Inflation reduces purchasing power, so future dollars buy less than today's dollars.
Common mistakes
- Treating a projection as a guarantee.
- Ignoring fees, taxes, and inflation that reduce real returns.
- Confusing nominal rate with effective annual return.
- Assuming the rate stays fixed for the whole period.
- Forgetting that early years add little interest compared to later years.
Try it yourself
Quick checks. Answers sit tucked under each question.
$0 start, $100 monthly, 6%, 1 year?
Future value $1,233.56, contributions $1,200.00, interest $33.56.
$1,000 start, $100 monthly, 5%, 5 years?
Future value $8,083.97, contributions $7,000.00, interest $1,083.97.
$5,000 start, $0 monthly, 6%, 5 years?
Future value $6,744.25, contributions $5,000.00, interest $1,744.25.
Questions
What is future value?
What a sum of money grows to after earning returns over time.
Does this include taxes and fees?
No. It is a gross projection before taxes, fees, and inflation.
Are monthly additions at the start or end of the month?
End of month, which is the common convention for this model.
What if the rate is zero?
Future value equals the starting amount plus additions, with no interest.
Is compounding frequency important?
Yes, but modestly. Monthly vs yearly compounding changes results slightly at normal rates.
Can I use this for college or retirement?
Yes as a starting estimate; pair it with a specific college or retirement planner.
Sources
- U.S. Securities and Exchange Commission: Investor.gov
- Financial Industry Regulatory Authority: Investor Education