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. A practical tip before you scale it up: build it once on a small block of test data, confirm the number against the tool on this page, and only then point it at your real sheet. That one habit catches almost every mistake while it is still cheap to fix, long before a wrong figure reaches a report or a colleague.

In Google Sheets

Everything above works in Google Sheets too. Excel and Sheets share the formula syntax used here; only the surrounding menus are arranged differently. That portability is deliberate — learn it once and it follows you between the two tools and across Windows and Mac. Nothing on this page is behind a login: the tool runs entirely in your browser, the formula is shown in full with one-click copy, and the steps work the same on Windows and Mac. That is the whole promise here — the exact answer, a way to prove it on your own numbers, and just enough context to make it stick. Treat “calculate geometric mean in excel” as a small building block rather than a chore. Once the inputs sit in their own cells and the formula reads from them, the same setup answers a dozen related questions with a tweak, and Excel keeps every dependent figure current as the data changes. The tool above is there so you can rehearse and verify before committing anything to a real workbook; the steps and worked example are there so the logic sticks. Get it right once and it stops costing you time — it starts saving it, every time the question comes back around.

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