ISNUMBER
Returns TRUE if a value is a number, FALSE otherwise.
ISNUMBER(value)Arguments
valueThe value to check
=ISNUMBER(A1)Checks if A1 contains a number
=ISNUMBER(SEARCH("text",A1))Tests if SEARCH found match
=IF(ISNUMBER(A1),A1*2,0)Only calculate if number
- •Dates are numbers (returns TRUE)
- •Text that looks like numbers returns FALSE
- •Use VALUE to convert text to numbers
- •Using ISNUMBER on a cell containing a number stored as text, expecting TRUE - it returns FALSE, since the cell's underlying type is text, not a number
- •Forgetting dates and times are stored as numbers internally, so ISNUMBER returns TRUE for a date cell, which surprises anyone expecting it to only flag plain numbers
- •Using ISNUMBER alone to validate user input when a more specific check combined with a range test would catch more real-world data problems
Why does ISNUMBER return FALSE for something that looks like a number?
The value is probably stored as text rather than a true number - common after importing data from a CSV or other system. Try VALUE() to convert it, or check for a leading apostrophe.
Does ISNUMBER return TRUE for dates?
Yes, dates and times are stored as serial numbers internally, so ISNUMBER treats them as numbers, not as a separate date type.
How do I convert a text number so ISNUMBER returns TRUE?
Wrap it in VALUE(), like VALUE(A1), which converts a numeric-looking text string into an actual number.
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