ISNUMBER Function (LibreOffice Calc)
The ISNUMBER function in LibreOffice Calc checks whether a value is a number. It is essential for data validation, conditional logic, cleaning datasets, and building robust spreadsheet workflows.
Compatibility
▾| Excel | ✔ |
| Gnumeric | ✔ |
| Google_sheets | ✔ |
| Libreoffice | ✔ |
| Numbers | ✔ |
| Onlyoffice | ✔ |
| Openoffice | ✔ |
| Wps | ✔ |
| Zoho | ✔ |
What the ISNUMBER Function Does ▾
- Returns TRUE if a value is numeric
- Returns FALSE for text, logical values, errors, or empty cells
- Useful for validating input and cleaning imported data
- Works with literals, formulas, and references
It is designed to be simple, reliable, and universally compatible.
Syntax ▾
ISNUMBER(value)
Arguments
- value:
Any value, expression, or cell reference.
Basic Examples ▾
Check if A1 contains a number
=ISNUMBER(A1)
Use with IF to validate numeric input
=IF(ISNUMBER(A1); "Valid"; "Invalid")
Check a literal number
=ISNUMBER(42)
Returns TRUE.
Check a numeric string
=ISNUMBER("42")
Returns FALSE — text is not a number.
Advanced Examples ▾
Convert text to number before checking
=ISNUMBER(VALUE(A1))
Useful for imported numeric text.
Check if a formula returns a number
=ISNUMBER(A1 * 2)
TRUE if A1 is numeric.
Detect numbers inside mixed data
=ISNUMBER(FIND("123"; A1))
TRUE if “123” appears in A1 (FIND returns a number).
Validate numeric ranges
=AND(ISNUMBER(A1); A1 > 0; A1 <= 100)
Check if a cell contains a date
=ISNUMBER(A1)
Dates are stored as numbers in Calc.
Check if a cell contains a time
=ISNUMBER(A1)
Times are also numeric.
Detect numeric results from text functions
=ISNUMBER(LEN(A1))
LEN always returns a number → TRUE.
Edge Cases and Behavior Details ▾
Text that looks like a number is NOT a number
=ISNUMBER("123")
Returns FALSE.
A cell containing a formula returning "" is NOT a number
=ISNUMBER("")
Returns FALSE.
A cell containing an error is NOT a number
=ISNUMBER(#N/A)
Returns FALSE.
A cell containing a boolean is NOT a number
=ISNUMBER(TRUE)
Returns FALSE.
A cell containing a date IS a number
=ISNUMBER(DATE(2024;1;1))
Returns TRUE.
A cell containing a time IS a number
=ISNUMBER(TIME(12;0;0))
Returns TRUE.
Common Errors and Fixes ▾
ISNUMBER returns FALSE unexpectedly
Cause:
- Value is text, even if it looks numeric
- Value contains spaces or hidden characters
- Value is a formula returning text
Fix:
Use VALUE(A1) or TRIM(A1) before checking.
ISNUMBER returns TRUE unexpectedly
Cause:
- Dates and times are numeric
- FIND, LEN, ROW, COLUMN return numbers
ISNUMBER used on a range
=ISNUMBER(A1:A10)
Returns a single TRUE/FALSE based on array context; use COUNT or SUMPRODUCT instead.
Best Practices ▾
- Use ISNUMBER to validate numeric input
- Use VALUE to convert numeric text before checking
- Use TRIM to clean whitespace
- Use AND with ISNUMBER for range validation
- Use ISNUMBER to detect dates and times
Related Patterns and Alternatives ▾
- Use ISTEXT to detect text
- Use ISBLANK to detect empty cells
- Use ISLOGICAL to detect TRUE/FALSE
- Use VALUE to convert numeric text
- Use COUNT or COUNTIF for numeric ranges
By mastering ISNUMBER and its companion functions, you can build clean, reliable, and error‑resistant data workflows in LibreOffice Calc.