Summary
ISNUMBER returns TRUE when a value is numeric. That includes regular numbers, dates, times, percentages, and other values Excel stores as numbers.
It returns FALSE for text, even when the text looks like a number. That is why it is one of the most useful cleanup checks in imported data.
Purpose
Returns TRUE only when Excel sees the value as numeric.
Return Value
TRUE means numeric. FALSE means not numeric.
Syntax
=ISNUMBER(value)You can use it on a cell, a formula result, or a direct value.
Arguments
- value - [required] The value you want to test.
ISNUMBER vs Other Functions
| Function | Main job | What it helps with |
|---|---|---|
ISNUMBER |
Checks for numeric values | Safe math and input validation. |
ISTEXT |
Checks for text values | Spotting text labels and text-formatted numbers. |
ISNONTEXT |
Checks for anything except text | Broader filtering that includes blanks and errors. |
TYPE |
Returns a type code | More detailed classification when TRUE or FALSE is not enough. |
Using ISNUMBER
This function is a good first line of defense when a formula should only run on numeric input. It helps prevent text placeholders, imported text numbers, and mismatched data from breaking your math.
One detail matters a lot in real sheets: dates and times return TRUE here because Excel stores them as numbers. That means ISNUMBER is also useful for checking whether a date field is really usable in date math.
Example 1 - Check a normal number
This is the basic pattern.
=ISNUMBER(B1)Check whether B1 is a number. Formula: =ISNUMBER(B1).
Example 2 - Reject a text number
Quotes turn the value into text, so the result is FALSE.
=ISNUMBER("50") // Returns FALSE.Check whether the text "50" counts as a number. Formula: =ISNUMBER("50").
Example 3 - Accept a date serial
Dates work here because Excel stores them as numbers underneath.
=ISNUMBER(C3)Check whether a date serial in C3 counts as a number. Formula: =ISNUMBER(C3).
Example 4 - Gate a calculation
This is a simple way to protect a formula from bad input.
=IF(ISNUMBER(A1),A1*2,"Check Input")Check whether A1 is numeric. Formula: =ISNUMBER(A1).
Conclusion Recap
- Main job:
ISNUMBERchecks whether a value is numeric. - Includes: Dates and times, because Excel stores them as numbers.
- Rejects: Text, including text that looks like a number.
- Best use: Safe-math checks and imported-data cleanup.
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