DUR2DAYS Function in Apple Numbers: Syntax, Examples and Troubleshooting

• Introduced: Documented in Apple’s Formulas and Functions Help 15.4; the original introduction release is not established.
• Availability: Supported by the current Apple Formulas and Functions Help 15.4 documentation for Numbers; no final supported-version endpoint is identified.
• Scope: Shared iWork function reference; the formatting steps below refer to Numbers for Mac. Older releases and individual-client introduction dates are not established here.
• Checked: October 14, 2026, against the official DUR2DAYS reference. Documentation and independent arithmetic checks; no native Numbers test.

=DUR2DAYS(duration)

duration is the single required argument: an elapsed-time value, or a reference to a cell containing one. There is no optional conversion mode or documented default input. The output is a number of days, rather than another duration value. Apple describes the input type in its argument and value guide.

For predictable practice data, create the duration with DURATION instead of relying on how a colon-separated text entry is interpreted. A bare number such as 1.5 does not state whether you mean days, hours or minutes; put it in the correct DURATION argument first. The formulas here use English-language commas and decimal points; use the function editor’s local syntax if your document uses different separators.

Create a Numbers table with at least six columns and eleven rows. Use A1 for Description, B1 for Duration and C1 for Total days. Enter the following formulas in B2:B7; do not type them as quoted text.

In C2, enter =DUR2DAYS(B2) and fill down through C7. C3 should refer to B3, and so on. Set C2:C7 to Number, with enough decimal places to inspect small results. Values marked ≈ are rounded here for display, not instructions to round the stored result.

A duration can exceed a day and can be negative. The negative row represents a signed time adjustment; the zero row is an explicit zero duration, not an empty cell. Do not replace the required argument with a blank and assume the same behavior.

One day corresponds to 86,400,000 milliseconds, or 24 hours. Divide the total elapsed milliseconds by 86,400,000 to check the result. This dimensional calculation is independent of a cell’s chosen display style.

Leave the practice data unchanged. In B10, enter =DURATION(0,0,36) for a 36-hour turnaround. In D10, type the numeric target 2, meaning two 24-hour days. In C10, enter =DUR2DAYS(B10); the expected result is 1.5. In E10, enter =D10-C10; the remaining allowance is 0.5 day, equivalent to 12 hours.

The meaning of the target matters. This is elapsed-time arithmetic, not a count of dates touched, office days, holiday exclusions or local daylight-saving transitions. If the rule is “within two business days,” define that calendar separately instead of treating 48 hours as an interchangeable deadline. A duration contains an amount of time, not the calendar context needed to decide which dates are working days.

• The result seems to lose precision: show more decimal places. On Mac, select the result cell, open Format > Cell, choose Number, and adjust Decimals. Apple’s formatting guide explains that displayed rounding does not change the value used in subsequent calculations.
• The input is a clock time: a date/time value and an elapsed duration are different types. Use TIME for a time of day, or construct the elapsed quantity with DURATION. Do not infer duration units from how a clock-style string looks.
• The formula is rejected: check the function spelling, the one required input, and whether B2 contains a real duration-producing formula. The function page does not enumerate exact error labels for every invalid text, missing argument or out-of-range case, so no particular error code is promised here.
• A downstream calculation fails: inspect its denominators and unit labels before wrapping it in IFERROR. Hiding an error does not fix an input expressed in the wrong unit.

The examples use exact millisecond arithmetic. Undocumented input coercion and precision limits remain unverified; displayed decimal places alone do not establish those limits.