Investment Return Calculator

Q: Is this the same as my account's stated return?

Close, but not identical. This is a money-weighted return over your actual contribution schedule. If you invested more near the start, your timing had more weight; if you added most money later, it had less. It's the honest number for what your deposits actually earned.

What did your money actually earn? Plug in what you started with, what you added each month, and what you ended with — this works backwards to your real annualized return.

With a $10,000 starting balance, $500 added monthly, and a final value of $150,000 after 10 years, your money earned about 12.2% per year on average. This calculator reverses the growth math: instead of predicting a future value from a return rate, it finds the return your real numbers actually produced. Enter what you started with, what you added, and what you ended with — it works out the honest annualized return, contributions and growth.

Your investment

Calculations run in your browser. Inputs are not stored.

Starting balance

Monthly contribution

Years invested

10 years

Final balance

Compound frequency

How often interest is credited to your balance — your monthly contribution stays the same.

Your annualized return over 10 years

6.0%

You invested$70,000

Growth to $150,000$80,000

ContributionsGrowth

Show yearly breakdown

Year	Contributions	Growth	Balance

How this calculation works

The formula

We take the exact compound formula used everywhere on this site and solve it for the monthly rate instead of the balance. Given starting balance P, monthly contribution M, final balance FV and N months:

FV = P·(1+i)^N + M·( ((1+i)^N − 1) / i ) → solve for i

The monthly rate i is found numerically (binary search), then annualized as your return. The result is a money-weighted return over your actual deposit schedule.

Assumptions

Contributions are added at the end of each month (ordinary annuity).
The result is a money-weighted annual return — it reflects your specific timing, not a market average.
Returns are assumed constant across the whole period; this isolates the average rate that would produce your final balance.
Fees, taxes and inflation are not included, so your true real-world return may differ.
If the final balance is below your total contributions, the return is negative.

View the formula →

Educational purposes only. Not financial advice. See the full methodology and disclaimer.

Investment returns, explained

How is the annual return calculated?

It solves the compound interest formula in reverse. Given your starting amount, monthly contribution, years and final balance, it finds the monthly rate i that makes FV = P(1+i)^N + M(((1+i)^N−1)/i), then annualizes it. The math is identical to our forward calculators — just solved for the rate instead of the balance.

Is this the same as my account's stated return?

Close, but not identical. This is a money-weighted return over your actual contribution schedule. If you invested more near the start, your timing had more weight; if you added most money later, it had less. It's the honest number for what your deposits actually earned.

What if my final balance is lower than I invested?

Then the calculated return is negative — the tool handles losses too. If the final balance is so low that even a -100% monthly rate can't explain it, the result is flagged as "below -100%", which usually means the inputs don't add up.

Why does this matter for judging my investing?

A simple "I made X% this year" ignores when you added money. Comparing your money-weighted return against a benchmark over the same period tells you whether your decisions (timing and contributions) helped or hurt versus just buying and holding.