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KitWren

Investment Calculator

Project how an investment grows with monthly contributions, rising contributions and inflation.

  1. Enter your numbers
  2. Results update as you type
  3. Copy the answer or share the link
Runs in your browser. Your data and files never leave your device.

About the Investment Calculator

Project the future value of an investment with a starting amount, monthly contributions that can increase each year, and an expected annual return — shown in future dollars and today’s money.

How does the Investment Calculator work?

The balance compounds monthly at the expected return, contributions are added each month, and the final value is also discounted by inflation so you can see its real buying power.

Investment Calculator formula

Bₘ = Bₘ₋₁ × (1 + r) + C
real value = nominal ÷ (1 + inflation)^years

Frequently asked questions

What return should I assume?

Use a conservative figure after fees. Long-run diversified share portfolios have historically returned more than cash, but with large ups and downs; no return is guaranteed.