ISNUMBER Function in Excel
The ISNUMBER function checks if a cell contains a numeric value and returns TRUE or FALSE. Master ISNUMBER with practical examples and error solutions.
Excel
Google SheetsExcelGoogle Sheets=ISNUMBER(value)Quick Answer
ISNUMBER function ISNUMBER function tests whether a value is numeric and returns TRUE for numbers or FALSE otherwise. Use `=ISNUMBER(value)` where value is the cell or expression to test. Available in Excel and Google Sheets, it's essential for data validation, conditional calculations, and filtering numeric entries from mixed data.
=ISNUMBER(value)Practical Examples
Basic Number Validation
Check if a cell contains a numeric value
Filter Numeric Values with IF
Display only numeric values from mixed data
Count Numeric Entries
Count how many cells contain actual numbers in a range
Validate Before Mathematical Operations
Safely perform calculations only on numeric values
Find Text Masquerading as Numbers
Identify cells with text-formatted numbers for data cleaning
Dynamic Array Filtering (Excel 365)
Filter a range to show only numeric values
Conditional Formatting Rule
Highlight cells that contain non-numeric data
Common Errors and Solutions
ISNUMBER returns #VALUE! error
This error typically occurs when the function is given an entire array or range as input in older Excel versions that don't support array formulas, or when there's a circular reference in the formula
1. Check if you're using ISNUMBER with an array formula - if so, use array formula syntax (Ctrl+Shift+Enter in older Excel) 2. For ranges, use with SUMPRODUCT: =SUMPRODUCT(--ISNUMBER(A1:A10)) instead of =ISNUMBER(A1:A10) 3. Verify there are no circular references by checking the Formulas tab → Error Checking 4. Make sure you're referencing a single cell, not a range, unless using array formula syntax
Always test ISNUMBER with a single cell reference first (=ISNUMBER(A1)), then extend to arrays only if your Excel version supports dynamic arrays or you're using proper array formula syntax
Example:
ISNUMBER returns TRUE for dates/times when expecting FALSE
Dates and times in Excel and Google Sheets are stored internally as numbers (dates as serial numbers since 1900, times as decimal fractions). Therefore, ISNUMBER correctly returns TRUE for date and time values, which might be unexpected if you're trying to distinguish dates from other numbers
1. To exclude dates, combine checks: =AND(ISNUMBER(A1), NOT(ISNUMBER(DATEVALUE(TEXT(A1,"mm/dd/yyyy"))))) 2. Use TYPE function instead: =TYPE(A1)=1 checks for numbers 3. For more specific checking, use ISDATE equivalent: =AND(ISNUMBER(A1), A1>1, A1<2958466) for valid date range 4. Or use custom validation: =AND(ISNUMBER(A1), FLOOR(A1,1)<>A1) to find only decimals
Remember that Excel stores dates as numbers (e.g., 45000 for 4/6/2023). If you need to distinguish dates from other numbers, use additional date-specific checks or the TYPE function for more granular control
Example:
ISNUMBER returns FALSE for numbers stored as text
When numbers are imported from text files, web sources, or CSV files, they're often stored as text with a leading apostrophe or due to cell formatting. ISNUMBER correctly returns FALSE because these are text values, not numbers, even though they look like numbers visually
1. Convert text to numbers: =VALUE(A1) or multiply by 1: =A1*1 2. Check both: =OR(ISNUMBER(A1), ISNUMBER(VALUE(A1))) to detect convertible text 3. Use this to find and flag problematic cells: =IF(AND(NOT(ISNUMBER(A1)), ISNUMBER(VALUE(A1))), "Convert", "OK") 4. Bulk convert: Select cells → click warning icon → "Convert to Number" 5. For entire column: =VALUE(A:A) or use Text to Columns feature
Always check imported data for text-formatted numbers using the formula above. When importing, use Power Query or proper data type specification. Enable Excel's "Number stored as text" error checking (File → Options → Formulas → Error Checking Rules)
Example:
Best Practices and Advanced Tips
Combine with SUMPRODUCT for Powerful Counting
Use =SUMPRODUCT(--ISNUMBER(range)) to count numeric values in a range containing mixed data types. This is more reliable than COUNT for data validation because COUNT might miss some numeric values stored as text. The double negative (--) converts TRUE to 1 and FALSE to 0.
Create Dynamic Named Ranges
Combine ISNUMBER with OFFSET and COUNTA to create dynamic named ranges that automatically expand to include only numeric entries. This is invaluable for charts and pivot tables that should only include valid numeric data.
Always Validate Before Math Operations
In production spreadsheets, wrap calculations with ISNUMBER checks to prevent #VALUE! errors. Use the pattern: =IF(ISNUMBER(A1), A1*multiplier, "Error: Invalid data"). This makes your workbooks more resilient to user input errors.
Dates Return TRUE
Remember that ISNUMBER returns TRUE for dates and times because Excel stores them as numbers internally. If you need to distinguish dates from other numbers, combine ISNUMBER with date-specific checks or use the TYPE function for more granular control.
Performance Optimization for Large Datasets
When working with thousands of rows, ISNUMBER is very fast because it's a native Excel function. However, combining it with volatile functions like INDIRECT can slow down recalculation. For maximum performance with large datasets, use ISNUMBER in helper columns rather than nested in complex array formulas.
Cross-Platform Consistency
ISNUMBER works identically in Excel (all versions), Google Sheets, and Excel Online. Unlike some modern functions with version requirements, ISNUMBER is universally supported, making it safe for shared workbooks across different platforms.
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Example Excel formula:
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