Investment Calculator
See how an investment grows from a starting balance and monthly contributions at a given return. Free compound-growth calculator with no signup.
Independently verified for accuracy
- Projected balance
- 106639.02
- Total contributed
- 70000
- Total growth
- 36639.02
This calculator projects what a starting balance plus a fixed monthly contribution grows into at an assumed annual return. Use it to set a savings target, compare contribution amounts, or estimate where a brokerage or index-fund account lands after a set number of years.
How this is calculated
It applies the standard future value formula with monthly compounding: the lump sum grows by (1 + r)^n while each end-of-month contribution is summed as an annuity, where r is the annual rate divided by 12 and n is years times 12.
How to use
- Enter your starting amount and monthly contribution.
- Enter an expected annual return and the number of years.
- Read the projected balance, total contributed, and total growth.
Examples
- $10,000 + $500/mo at 7% for 10 yr:
Balance $106,639.02 - $0 + $200/mo at 6% for 20 yr:
Balance $92,408.18
FAQ
- How is the future value calculated?
- The starting balance compounds monthly at the annual rate divided by 12, and each monthly contribution is added at the end of the month and compounds for the remaining time.
- Is the return guaranteed?
- No. The rate you enter is an assumption. Real returns vary year to year and can be negative. Use a conservative long-run estimate and treat the result as a projection, not a promise.
- Does it account for inflation or taxes?
- No. The result is a nominal, pre-tax figure. To estimate buying power, lower your assumed return by your expected inflation rate.