ROUNDDOWN
Supported, behaves as documentedCategory: Math and trigonometry · Last tested 2026-09-01
Real compatibility results for the ROUNDDOWN function: executed in Excel for the web, Google Sheets and LibreOffice Calc, with desktop Excel behavior from Microsoft’s official documentation (we do not run desktop Excel — Excel for the web is a different application and is executed separately). Syntax and links to that documentation are below.
Support matrix
| Engine | Documented | Live-tested | Verdict |
|---|---|---|---|
| Excel (desktop) | Yes | No — documented only | n/a |
| Excel for the web | — | Yes (recalc, 2026-09-01) | Supported, behaves as documented |
| Google Sheets | Yes | Yes (Drive import, 2026-08-29) | Supported, behaves as documented |
| LibreOffice Calc | Yes | Yes (25.8.7.3, 2026-07-29) | Supported, behaves as documented |
LibreOffice version history
We executed the same test cases under each LibreOffice release to show exactly when ROUNDDOWN’s support changed — not documentation claims, real results.
| LibreOffice version | Verdict | Tested |
|---|---|---|
| 24.2.0.3 | Supported, behaves as documented | 2026-08-29 |
| 24.8.7.2 | Supported, behaves as documented | 2026-08-29 |
| 25.2.0.3 | Supported, behaves as documented | 2026-08-29 |
| 25.8.7.3 | Supported, behaves as documented | 2026-07-29 |
Executed test cases
Excel for the web (executed 2026-09-01 via OneDrive recalculation)
These values come from Excel for the web, not from desktop Excel. They are two different implementations of the calculation engine, and this run measured only the web one: the corpus was uploaded to OneDrive as .xlsx, recalculated by Excel for the web on open, and downloaded again for readback. Excel for the web is a rolling service with no pinnable version, so the run is identified by its date. Where a value here disagrees with the Expected column — which is Microsoft’s documentation of the desktop product — we cannot tell you whether the web engine diverges from the desktop one or the documentation is wrong about both, because we do not run desktop Excel.
| Formula | Description | Result | Expected | Verdict |
|---|---|---|---|---|
| =ROUNDDOWN(3.9,0) | Always rounds toward zero, regardless of the discarded digit | 3 | 3 | Matched |
| =ROUNDDOWN(-3.9,0) | For negative numbers, 'down' means toward zero (less negative), not toward negative infinity | -3 | -3 | Matched |
| =ROUNDDOWN(21.5,-1) | Negative num_digits rounds to the left of the decimal point (nearest multiple of 10 here) | 20 | 20ProvenanceRounding 21.5 down (toward zero) to the nearest 10 gives 20 -- this is Microsoft's own documented example for ROUNDDOWN, and the direct counterpart to ROUNDUP(21.5,-1)=30 |
Matched |
| =ROUNDDOWN(3.14159,2) | Rounds down to 2 decimal places, discarding the remaining digits | 3.14 | 3.14 | Matched |
Google Sheets (executed 2026-08-29 via Drive import)
Google Sheets is a rolling service with no pinnable version, so this run is identified by its date. The corpus was imported to Drive as .xlsx, recalculated by Sheets, and exported back for readback.
| Formula | Description | Result | Expected | Verdict |
|---|---|---|---|---|
| =ROUNDDOWN(3.9,0) | Always rounds toward zero, regardless of the discarded digit | 3 | 3 | Matched |
| =ROUNDDOWN(-3.9,0) | For negative numbers, 'down' means toward zero (less negative), not toward negative infinity | -3 | -3 | Matched |
| =ROUNDDOWN(21.5,-1) | Negative num_digits rounds to the left of the decimal point (nearest multiple of 10 here) | 20 | 20ProvenanceRounding 21.5 down (toward zero) to the nearest 10 gives 20 -- this is Microsoft's own documented example for ROUNDDOWN, and the direct counterpart to ROUNDUP(21.5,-1)=30 |
Matched |
| =ROUNDDOWN(3.14159,2) | Rounds down to 2 decimal places, discarding the remaining digits | 3.14 | 3.14 | Matched |
LibreOffice Calc 25.8.7.3 (tested 2026-07-29)
| Formula | Description | Result | Expected | Verdict |
|---|---|---|---|---|
| =ROUNDDOWN(3.9,0) | Always rounds toward zero, regardless of the discarded digit | 3 | 3 | Matched |
| =ROUNDDOWN(-3.9,0) | For negative numbers, 'down' means toward zero (less negative), not toward negative infinity | -3 | -3 | Matched |
| =ROUNDDOWN(21.5,-1) | Negative num_digits rounds to the left of the decimal point (nearest multiple of 10 here) | 20 | 20ProvenanceRounding 21.5 down (toward zero) to the nearest 10 gives 20 -- this is Microsoft's own documented example for ROUNDDOWN, and the direct counterpart to ROUNDUP(21.5,-1)=30 |
Matched |
| =ROUNDDOWN(3.14159,2) | Rounds down to 2 decimal places, discarding the remaining digits | 3.14 | 3.14 | Matched |
Docs & syntax
- Excel (desktop): official documentation
- Google Sheets: official documentation
- LibreOffice Calc: official documentation