Excel QUARTILE Function

What this does

QUARTILE splits a dataset into four equal parts, returning the value at whichever boundary you request. Its second argument is an index from 0 to 4, not a percentage, which trips people who come to it from PERCENTILE. Its practical value is the interquartile range: quartile 3 minus quartile 1 gives the spread of the middle half, and the standard outlier rule flags anything beyond 1.5 IQRs outside those bounds. That is also exactly what a box plot draws, so QUARTILE is how you replicate one numerically. 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. The difference between a quick fix and a sheet you can trust is the extra minute you spend validating “excel quartile function”. Start on a copy or a tiny sample, keep the affected formula visible, and compare the result with the tool above before you touch the real workbook. 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. The point is a calculation you can defend to a CFO or an auditor, but the practical win is that someone else can open the file and understand what happened without asking you.

A worked example

Order values in B2:B200: =QUARTILE.INC(B2:B200, 1) and =QUARTILE.INC(B2:B200, 3) give the quartile bounds, and their difference is the IQR. An upper outlier threshold is =QUARTILE.INC(B2:B200,3) + 1.5*(QUARTILE.INC(B2:B200,3)-QUARTILE.INC(B2:B200,1)). QUARTILE is the numeric basis of the box plot and the standard outlier rule, which makes it the fastest way to describe spread without assuming a distribution. 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. Keep this page bookmarked for the next time the same question comes up. Better still, repeat the steps once in your own workbook — doing it yourself is what turns a copied answer into something you remember. If you take one thing from this page on “excel quartile function”, make it the habit rather than the keystrokes: set the problem up with labelled inputs, reference those cells, and let Excel do the recomputing. Bookmark the page for the syntax, but do the example once in a blank sheet and check it against the tool above — five minutes of hands-on practice fixes the method in memory far better than re-reading, and it surfaces the small snags while they are still harmless. After that the technique is genuinely yours: faster than searching for it again, and reliable enough to drop into work that other people depend on.

Common mistakes

• Passing 0.25 instead of 1 — the argument is an index from 0 to 4, not a proportion.
• Using QUARTILE.EXC on small samples where the boundary is undefined, which returns #NUM!.
• Reporting quartiles on a tiny dataset, where they are unstable and a simple sorted list says more.

Frequently asked questions