Investment Growth Calculator
Estimate how a starting lump sum and regular monthly investing could grow over time. Adjust the assumptions and compare outcomes instantly.
Model a scenario
Starting lump sum, up to $1 trillion.
Invested monthly, up to $1 billion per month.
Hypothetical annual return from -100% through 100%.
Use a whole number from 0 through 100.
In 20 years, about 57% of the ending value is modeled investment growth.
- Total contributed
- $130,000.00
- Investment growth
- $170,850.72
- Effective annual yield
- 7.229%
What if the return changes?
How investment growth is calculated
The starting lump sum grows by compounding at the selected frequency, while monthly contributions are modeled as an annuity added at the end of each month. Future value is the sum of the grown principal and the grown contributions; investment growth is future value minus everything you put in.
FV = P(1 + r/n)nt + PMT × (((1 + i)kt − 1) / i)- FV
- Future value
- P
- Initial investment
- r
- Expected annual return
- n
- Compounding periods per year
- PMT
- Monthly contribution
- i
- Effective rate per contribution period
$10,000 plus $500 per month for 20 years
At a hypothetical 7% expected annual return compounded monthly, $10,000 invested initially plus 240 monthly contributions of $500 produces a projected future value of $300,850.72. You contributed $130,000 in total; the remaining $170,850.72 is modeled investment growth.
This is a hypothetical, educational projection. Actual investment returns can change, and taxes, fees, inflation, and market volatility are not included unless explicitly modeled.
What this calculator assumes
- The expected annual return stays constant for the full period.
- Contributions are made at the end of each month, every month.
- All growth remains invested and compounds.
- Taxes, fees, withdrawals, and inflation are excluded.
- Money values are rounded to the nearest cent for display.
Investment growth FAQ
Does this calculator guarantee an investment return?
No. It applies a single constant hypothetical return to illustrate one scenario. Real investment returns vary year to year and can be negative.
How is investment growth different from total contributed?
Total contributed is the money you put in — the starting lump sum plus every monthly contribution. Investment growth is the additional value the calculator projects on top of that from compounding.
Sources and review notes
- U.S. Securities and Exchange Commission, Investor.gov — Compound Interest Calculator
- Financial Consumer Agency of Canada — Savings and investments
Methodology last checked Jul 14, 2026. Formula implementation is covered by deterministic unit tests. No financial professional review is claimed yet.