How to Calculate GEOMEAN 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. The same idea underpins a lot of everyday Excel work, so the few minutes spent getting it right here pay back across every sheet you build afterwards. Treat it as a pattern, not a one-off, and it stops being something you look up and starts being something you reach for. Treat “calculate geomean 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. If there is any chance you will reuse this, drop it into a small template tab right now: a labelled input area on the left and the formula beside it, checked once against the tool above. Next time the same question comes up, the answer is a single paste away instead of a rebuild from memory.

In Google Sheets

If you are in Google Sheets rather than Excel, the good news is that the formula shown here is identical and the workflow barely changes — menus sit across the top instead of in a ribbon, and a few function names differ slightly, but anything you build here moves across with little or no rework. 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. Here is the takeaway for “calculate geomean in excel”: copy the answer if you are busy, but if you have a spare few minutes, rebuild the example in Excel yourself with the tool above open beside it. That single pass — type it, run it, watch the result move when you change an input — is what turns a formula you found into a technique you trust. Keep your inputs labelled and referenced, never hard-coded, and the same sheet stays correct and auditable as it grows. Done that way, you will not need to look this up again, and you will be the person others ask.

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