Note: Excel has several built-in data validation rules for numbers. This page explains how to create your own validation rule based on a custom formula.

To allow only numbers in a cell, you can use data validation with a custom formula based on the ISNUMBER function. In the example shown, the data validation applied to C5:C9 is:


Generic formula



Data validation rules are triggered when a user adds or changes a cell value.

The ISNUMBER function returns TRUE when a value is numeric and FALSE if not. As a result, all numeric input will pass validation.

Be aware that numeric input includes dates and times, whole numbers, and decimal values.

Note: Cell references in data validation formulas are relative to the upper left cell in the range selected when the validation rule is defined, in this case, C5.

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.