DAYS Function in Google Sheets: Examples, Pitfalls & Compatibility

=DAYS(end_date, start_date)

end_date (required): The date at the end of the interval; this is the first argument.

start_date (required): The date at the start of the interval; this is the second argument.

Examples use English function names, comma argument separators and decimal points. Adapt formula separators to your workbook settings, not punctuation inside quoted text.

Use DAYS for elapsed calendar days, including weekends. Use NETWORKDAYS for a working-day rule. DAYS does not by itself count both endpoints as separate full days and is not the same function as DAY, which extracts a day-of-month number.

Each example is independent. Where input cells are listed, enter those values first; otherwise the formula is self-contained. Expected outputs are independently checked calculations or documented error expectations, not captured results from Google Sheets.

Example 1: Count a forward calendar interval

=DAYS(DATE(2026,10,12),DATE(2026,10,1))

Expected result: 11.

The interval is eleven elapsed calendar days, not twelve inclusive dates.

Example 2: Check a same-day pair

=DAYS(DATE(2026,10,12),DATE(2026,10,12))

Expected result: 0.

Both endpoints refer to the same date, so the elapsed difference is zero.

Example 3: Include a leap-day boundary

=DAYS(DATE(2024,3,1),DATE(2024,2,28))

Expected result: 2.

Using DATE components avoids ambiguous text parsing while making the leap-day contribution visible.

Label the source columns Start and End, then write DAYS with End first even when Start appears first in the table. Check a same-day pair, a forward interval and a reversed interval. If the reporting policy counts both endpoints, apply that as a separately documented rule only after validating chronological order. A negative interval should usually be investigated before an inclusive-count adjustment.

The sign is reversed. Check argument order. End date comes first. Do not apply ABS automatically if reversed dates would indicate a data problem.

A same-day interval returns zero. That is an elapsed-day result. An inclusive attendance or occupancy rule is a different calculation.

Weekends are included. DAYS is a calendar interval calculation, not a business-day count.

Dates imported as text are interpreted differently. Use validated date cells or DATE instead of ambiguous regional strings.

Google documents end_date before start_date and includes leap days. One help example has an inconsistent sign relative to its written date order. This guide uses explicit DATE expressions and independently checked calendar differences rather than reproducing that inconsistency; reversed-date behavior should also be checked natively. See the vendor reference for the current definition.

The ordinary DATE-based calendar intervals have the same intended meaning. Numeric timestamps, text parsing, inclusive-count policies and historical serial systems need separate checks. The independent calendar check here is not a native application test.

Compare the DAYS guide for Microsoft Excel and its official documentation. Having a guide in both libraries establishes two documented references, not a certificate of identical behavior across releases, locales or file conversions.

DATE, DAY, NETWORKDAYS, DATEDIF · All Google Sheets functions.

Editorial verification: Official references retrieved on 2026-10-12. The three worked cases are included in this release’s reproducible Python checking suite. It checks the stated arithmetic, calendar or text model and the expected documented error classification; it is not the Google Sheets calculation engine. No native application run, UI screenshot, maximum-size benchmark or cross-version certification is claimed. Review the editorial testing standards before relying on a formula in a critical workbook.