Investment Growth Calculator
The Investment Growth Calculator projects how a starting balance plus regular monthly contributions grow at an assumed annual return, separating what you deposited from the interest it earned.
What this means
Each contribution buys more of the portfolio, and each year the balance earns returns on top of earlier returns. This compounding is what turns steady deposits into meaningful wealth.
How we calculate it
Formula
FV = P(1+r)^n + C × ((1+r)^n − 1)/r — with P start, C monthly deposit, r monthly rate, n months.Worked example
$10,000 invested with $500/mo for 20 years at 7%:
- 1Future value ≈ $298,077
- 2Total deposited ≈ $130,000
- 3Investment growth ≈ $168,077
Important assumptions
- Deposits are made monthly at the start of the month.
- The annual return stays constant and ignores taxes and inflation.
Frequently asked questions
What return should I assume?
A diversified portfolio has historically averaged around 7% before inflation, but past performance doesn't guarantee future results. Stress-test with a range.
Should I count this as my only retirement plan?
Treat projections as a planning tool, not a guarantee. Revisit annually and adjust contributions as your income and goals change.