Home / Money lab / Compound growth

What will my money grow to?

A starting amount, a monthly deposit and a steady yearly return. See the balance year by year and how much of it is growth rather than your own money.

Compound growth calculator

Compound growth inputs

Starting amount

Added each month

Yearly return

Years

Inflation (for today's dollars)

Show the math

The balance is updated once a month. Your yearly return r is turned into the equivalent monthly rate, so a 7% year really is 7% (about 0.565% a month), and each deposit lands at the end of the month.

g = (1 + r)^(1/12) − 1 · balance = P(1 + g)^n + C·((1 + g)^n − 1) / g

P is the starting amount, C the monthly deposit, n the number of months.
“Today's dollars” divides the result by (1 + inflation)^years, so you can compare it with prices now.
Doubling time is ln 2 ÷ ln(1 + r). The rule of 72 (72 ÷ 7 ≈ 10.3 years) is the quick mental version.
Real markets don't return the same amount every year. Taxes and fees are not included; the fund fee calculator shows what fees do.

Why the big numbers come late

Growth is earned on growth. In the first years most of the balance is your own deposits; later, most of each year's increase comes from returns on returns. With the starting example ($10,000 plus $200 a month at 7%), growth only passes your total deposits in year 16 of 25. Stopping early costs more than it seems.

What it leaves out

Bumpy returns. Markets don't pay 7% every year. A steady rate shows the arithmetic, not a forecast.
Fees and taxes. A 1% yearly fee or tax drag changes the end result a lot. Try the fund fee calculator.
Inflation. Tick the inflation box to see the result in today's dollars.