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ISNUMBER

Checks whether a value is a number and returns TRUE or FALSE.

Quick Example​

=ISNUMBER(A1)

Returns TRUE if A1 contains a number, FALSE otherwise.

Syntax​

=ISNUMBER(value)

Arguments​

  • value (required): The value to check

Examples​

=ISNUMBER(123)                       // TRUE
=ISNUMBER("123")                     // FALSE (text, not number)
=ISNUMBER(A1)                        // TRUE if A1 contains number
=ISNUMBER(TODAY())                   // TRUE (dates are numbers)
=IF(ISNUMBER(A1), A1*2, "Not a number")

What Counts as a Number​

Returns TRUE For​

  • Integers: 1, 100, -5
  • Decimals: 3.14, -0.5
  • Dates: DATE(2025, 12, 25)
  • Times: TIME(14, 30, 0)
  • Currency values
  • Scientific notation: 1.5E+10

Returns FALSE For​

  • Text: "Hello", "123"
  • Text numbers: "123" (stored as text)
  • Blank cells
  • Logical values: TRUE, FALSE
  • Errors: #DIV/0!, #VALUE!

How It Works​

Does Not Coerce​

ISNUMBER checks the actual data type, it doesn't try to convert text to numbers:

=ISNUMBER("100")  // FALSE (text that looks like number)
=ISNUMBER(100)    // TRUE (actual number)

Error Handling​

Returns FALSE for errors (does not propagate them):

=ISNUMBER(#DIV/0!)  // FALSE

Common Use Cases​

  • Validate input: =IF(ISNUMBER(A1), "Valid", "Enter a number")
  • Count numbers: =COUNTIF(A1:A10, ISNUMBER(A1:A10))
  • Conditional formatting: =ISNUMBER(A1)
  • Data type checking: =IF(ISNUMBER(A1), A1, 0)

Using with Ranges​

=ISNUMBER(A1:A5)

For a range, returns TRUE only if ALL cells are numbers.