Compound Interest
Change any value and the rest adjust automatically. Edit the final balance to solve backwards for the initial investment.
| Year | Annual Contribution | Cumulative Contributions | Cumulative Interest | Annual Interest | Balance |
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About this tool
Enter a starting value, an ending value and the time between them, and this calculator returns the compound annual growth rate: the single steady yearly rate that would have produced that outcome.
CAGR is the honest way to compare investments held for different lengths of time, because it strips the period length out of the comparison. It is also the honest way to deflate a brag: a stock that tripled sounds heroic until CAGR reveals it took fifteen years, a 7.6% annual rate.
What is CAGR?
Compound annual growth rate: the constant yearly rate that carries the starting value to the ending value over the period, compounding included.
Why is CAGR lower than average return?
Because volatility drags on compounding. Gaining 50% then losing 33% averages to +8.5% arithmetically but leaves you exactly where you started. CAGR captures that reality; simple averages hide it.