How to Calculate Geometric Mean in Excel

What this does

GEOMEAN returns the geometric mean, which is the correct average for anything that compounds. Averaging yearly growth factors arithmetically overstates the result: a year of +50 % followed by a year of -50 % averages to 0 % arithmetically but actually leaves you down 13.4 %, which is what GEOMEAN reports. HARMEAN is the right average for rates expressed per unit — average speed over equal distances, average price-earnings across equal investments. Both require strictly positive values and return #NUM! otherwise. Keep the inputs visible and clearly labelled and the whole thing stays auditable — anyone who opens the file later, including you, can see at a glance exactly what feeds the result and change one assumption without hunting through the formula. Treat “calculate geometric mean in excel” as a small repeatable workflow rather than a one-off click you hope to remember next time. Use a small test block before the live file, so any surprise in the affected cells shows up while it is still harmless. When a formula is involved, keep the inputs labelled beside it, reference cells instead of typing values, and apply number formatting only after the result checks out. That turns a calculation you can defend to a CFO or an auditor into a method you can reuse, explain, and defend when the workbook leaves your screen.

A worked example

Average annual growth from factors 1.5 and 0.5: =GEOMEAN({1.5, 0.5}) returns 0.866, a true 13.4 % annual decline, where AVERAGE returns a misleading 1.0. Average speed over two equal legs at 40 and 60 km/h: =HARMEAN({40, 60}) returns 48, not the 50 an arithmetic mean would give. GEOMEAN is the only correct average for compounding, and using AVERAGE instead is one of the most common quiet errors in performance reporting. Check the referenced cells, argument order and result type in your workbook. Start with the worked example before changing an input, then compare the changed result with the calculation you expected. An error value or a result of a different type is a reason to inspect the inputs and arguments.

In Google Sheets

Google Sheets support for this task has not been verified. Check the function, arguments and workflow in the target product before transferring the example. Matching formula notation does not establish identical behaviour. Nothing on this page is behind a login or a download: the exact answer is at the top, and the detail below it is there for when you need it. That is the whole promise here — the answer first, and just enough context to make it stick. For “calculate geometric mean in excel”, keep the input cells and the result visible while you check the formula in Excel. Follow the worked example and change one input at a time. The steps explain the workbook calculation; this page does not run a live calculator for that task.

Common mistakes

• Passing rates rather than factors, where a negative rate returns #NUM!.
• Using AVERAGE on growth factors, which systematically overstates compound performance.
• Confusing the two: geometric for compounding, harmonic for per-unit rates.

Frequently asked questions