Excel ISERROR Formula

What this does

ISERROR returns TRUE for every error type: #N/A, #VALUE!, #REF!, #DIV/0!, #NAME?, #NUM! and #NULL!. Its close relative ISERR does the same but excludes #N/A, which is often what you actually want. The warning that belongs on this function is that blanket error suppression hides real bugs — a formula wrapped in ISERROR keeps working after someone deletes the column it referenced, silently returning a fallback instead of the #REF! that would have told you. Prefer the narrower test whenever you can name the error you expect. 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 “excel iserror formula” 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 formula 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

Counting how many rows in a calculated column are broken: =SUMPRODUCT(--ISERROR(D2:D500)) gives a data-quality figure worth watching. Distinguishing the two cases explicitly: =IF(ISNA(lookup), "not found", IF(ISERROR(lookup), "formula error", lookup)) handles each on its own terms. ISERROR is the broadest error test, and knowing when NOT to use it is what keeps a workbook debuggable. 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 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. If you take one thing from this page on “excel iserror formula”, 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

• Blanket-wrapping every formula, which hides #REF! and #NAME? faults that should be fixed rather than suppressed.
• Using ISERROR where ISNA was meant, so a legitimate "not found" and a genuine bug get the same treatment.
• Writing =IF(ISERROR(x), fallback, x), which evaluates x twice — IFERROR does it once.

Frequently asked questions