Lookup & Reference
HSTACK Function in Excel
Appends arrays horizontally (stacks columns).
Syntax
- =HSTACK(array1, [array2], ...)
Arguments
- array1 (required): First array
- array2 (optional): Additional arrays to stack
Examples
- =HSTACK(A1:A5, C1:C5) - Combine two columns - Result: 5x2 array
When to use HSTACK
- Use HSTACK when you need to retrieve values from a table or range based on a key.
- Confirm data types match (text vs number) and trim spaces before lookups.
- Pair with [IFERROR](/functions/iferror/) or [IFNA](/functions/ifna/) for cleaner reports.
- See the [lookup functions guide](/guides/excel-lookup-functions-guide/) for VLOOKUP, XLOOKUP, and INDEX MATCH paths.
Common HSTACK mistakes
- #N/A often means the key is missing or exact match is wrong — see [#N/A error](/errors/na/).
- Lock table references with $ when copying formulas down a column.
- Compare legacy vs modern lookups in [XLOOKUP vs VLOOKUP](/compare/xlookup-vs-vlookup/).
Common errors
- Requires Excel 365
- Arrays should have same row count
Use cases
- Combine columns
- Join tables
- Merge data
Frequently asked questions
- What is HSTACK in Excel? HSTACK combines arrays horizontally, placing them side by side. =HSTACK(A1:A10, B1:B10, C1:C10) creates a 3-column array. It's the horizontal equivalent of VSTACK, which stacks vertically.
- How do I add a calculated column to existing data? Use =HSTACK(A1:C10, formula_array). Example: =HSTACK(A1:C10, A1:A10*B1:B10) adds a column with row-by-row multiplication. Great for adding totals, percentages, or derived values.
- What happens if arrays have different row counts? HSTACK pads shorter arrays with #N/A to match the tallest array. Use IFERROR to handle this: =IFERROR(HSTACK(array1, array2), ""). Or ensure arrays have matching row counts before stacking.
Editorial review
- Reviewed by Excel.Directory Editorial Team. Updated May 2026.