Why dates instead of a number of years
Most CAGR calculators ask you for a whole number of years. Real periods rarely are one. A fund bought on 15 March 2019 and sold on 7 August 2026 spans seven years and just under five months — enter that as “7 years” and your growth rate comes out too high, because you have credited the same total growth to a shorter period.
This calculator counts the actual days between the two dates and annualizes from there, so the answer reflects the period you really held the position.
How the day count works
The calculation converts elapsed days into years, then applies the standard CAGR formula:
Years = days ÷ 365.25CAGR = (End Value / Start Value) ^ (1 / Years) − 1
The divisor is 365.25 rather than 365 because roughly one year in four is a leap year. Over a short period the difference is negligible; over twenty years, using a flat 365 overstates the elapsed time by about five days and nudges the rate down slightly. Both conventions are defensible and you will see both in the wild — the important thing is knowing which one a given number was produced with.
Note that this is calendar time, not trading days. If you are annualizing a return over trading days, the convention is usually 252 days per year instead, which produces a different figure.
Worked example
A holding worth 100,000 on 15 March 2019 is worth 250,000 on 7 August 2026. That is 2,703 days, or 7.40 years.
CAGR = (250,000 / 100,000) ^ (1 / 7.40) − 1 ≈ 12.98%Rounding the period to seven years instead would give 13.94% — almost a full percentage point of overstatement from a rounding decision alone. On a fund fact sheet or a board slide, that is the difference between a defensible number and one that will not reconcile.
When you need this
- Annualizing an investment return between a purchase date and a sale date.
- Comparing two holdings bought and sold at different times, on a like-for-like basis.
- Working out a growth rate between two month-end reporting dates.
- Measuring growth across a period that starts or ends mid-year.
Questions
What if the end value is lower than the start value?
You get a negative CAGR, which is the annualized rate of decline. That is a valid and often useful result — a fall from 100,000 to 60,000 over three years is an annualized decline of about 15.7%.
Does the order of the dates matter?
The end date must be after the start date. If it is not, the calculator will tell you rather than returning a nonsensical figure.
Can I use it for periods shorter than a year?
Yes, and the maths holds, but read the result carefully. Annualizing a two-month return projects that pace across a full year, which can produce very large numbers from small moves. A 10% gain over two months annualizes to roughly 77%, which says more about the extrapolation than about the investment.
Why does my broker show a different number?
Usually because the broker is calculating a money-weighted return that accounts for deposits and withdrawals during the period. CAGR only looks at the first and last values. If money moved in or out along the way, the two figures answer different questions and will not match.