ISO.CEILING Function (LibreOffice Calc)

ISO.CEILING moves a number up toward positive infinity to a multiple of a chosen step. The step can be negative in the argument—the function ignores its sign. This means that positive numbers become larger or stay unchanged, while negative numbers can become less negative. For example, -45.67 rounded upward to a multiple of 2 becomes -44, not -46. This differs from rounding away from zero. LibreOffice Help, ISO.CEILING, reviewed 2026-10-13.

In one line: =ISO.CEILING(3.45;2) returns 4. It is useful for whole-box purchasing, price increments, time slots and any other positive-direction rounding rule. Do not use it when your policy says “always increase the absolute magnitude” of a negative number.

=ISO.CEILING(Number [; Significance])

The square brackets in the syntax documentation mean that the second argument is optional; do not type square brackets into your formula. The formulas here use ; between arguments and . for decimal fractions in an English-language Calc setup. Other locales or formula-separator preferences may display a comma for decimal fractions or a different argument separator. Official syntax and default, retrieved 2026-10-13.

A useful independent mathematical model for a nonzero step s is:

s = ABS(Significance)
ISO.CEILING(x; s) ≈ s × mathematical_ceiling(x / s)

The mathematical ceiling is the smallest integer greater than or equal to its input. The ≈ reminds you that spreadsheet floating-point arithmetic can introduce precision effects near exact boundaries. This is a mathematical check, not a promise that the nested Calc formula CEILING(x/s) has identical compatibility and error semantics. In the tested Calc 25.2.3.2, a zero step returned 0 rather than using this nonzero-step model.

Enter each formula into a blank cell. Expected values below were observed natively with LibreOffice Calc 25.2.3.2 on Linux on 2026-10-13, and independently checked using decimal arithmetic.

Cell-reference example: purchasing full cartons

Set up this table, entering the labels in A1–A5 and the sample values/formulas in B1–B5:

The results are 144 units, 6 cartons, and 19 surplus units. This makes the rounding rule explicit: buy enough complete cartons to meet or exceed demand. If the box size is zero, missing, or invalid, do not silently use a result of zero; validate the input first.

=IF(OR(B2<=0;NOT(ISNUMBER(B1));NOT(ISNUMBER(B2)));"Check quantities";ISO.CEILING(B1;B2))

This is a suggested data-validation guard, not an inherent validation performed by ISO.CEILING. If fractional carton sizes are not allowed, add a whole-number check, for example B2=INT(B2).

More practical uses

Prices in increments of five cents. With an unrounded selling price in D2, use =ISO.CEILING(D2;0.05). For 72.41, the native result was 72.45. Currency rounding policies vary; this is a demonstration of a mathematical step, not a legal recommendation for cash/tax rounding.

15-minute slot allocation. Calc stores dates and times as day-based serial values. A 15-minute interval is 15/1440 days. For a time value in A2, =ISO.CEILING(A2;15/1440) can move to the next quarter-hour. Format the result as a date/time. Verify dates, time zones, daylight-saving changes and scheduling policies separately; this is numeric serial rounding, not a timezone-aware calculation.

Reproducible validation. If the value in E2 is the computed multiple and B2 is a strictly positive step, =MOD(E2;B2) should be near zero (allow for floating-point tolerance rather than demanding exact equality). A workbook with 24-unit cartons can also verify E2>=B1.

These related functions have distinct rounding or compatibility rules:

The official Help explicitly identifies CEILING.PRECISE and ISO.CEILING as equivalent in their numerical result. They have separate documented names and compatibility namespaces; use the documented function name appropriate to the workbook. Official Help, equivalence.

The following are observations from Calc 25.2.3.2 (Linux), not a guarantee of identical error codes in every locale or release. The official function definition states that nonnumeric arguments are invalid.

Surprising negative results? Check whether the rule should mean toward +∞, toward zero, away from zero, or to the nearest multiple. These are four different things. For instance, =ISO.CEILING(-45.67;2) gives -44 whereas =FLOOR.PRECISE(-45.67;2) gives -46.

Unexpected decimal tail? Binary floating-point storage can show small residuals. Keep the underlying calculation separate from cell formatting; do not use displayed decimal places as proof of exact arithmetic. In important financial workflows, independently verify boundary cases and actual required rounding rules.

Formula displays literally? Make sure the cell is not formatted as Text and that the formula begins with =. With localized separators, use the separators accepted by your Calc configuration.

LibreOffice Help states that ISO.CEILING has been available since LibreOffice 4.3. It identifies the compatibility function namespace as COM.MICROSOFT.ISO.CEILING and says that the function is not part of the ODF 1.3 OpenFormula function set. This does not mean the name is unusable in an ODS document; it means portability requires attention to the extension namespace and to the target application’s parser. LibreOffice Help, technical information.

Native execution was verified on Calc 25.2.3.2 on Linux, 2026-10-13. The official online Help showed the LibreOffice 26.8 label when checked, so its current text should not be misrepresented as native 25.2 testing. Windows, macOS, Excel, Google Sheets and other spreadsheet engines were not executed for this guide. Do not infer compatibility merely because similarly named functions exist elsewhere. For .xlsx handoffs, test sample negative-number and zero-step cases after importing and recalculating.

A native UNO-driven Calc workbook executed 35 numerical assertions for ISO.CEILING; all matched independent Python Decimal ceiling calculations to the documented tolerance. The batch also recorded 12 native ISO.CEILING diagnostics, with the raw formulas, displayed results, internal errors, script, and ODS workbook. These are observations, not a guarantee of future-version behavior.

Dated, claim-level official references (reviewed 2026-10-13):

1. LibreOffice Help: Ceiling functions — ISO.CEILING syntax, default, sign handling, examples, availability, extension namespace.
2. LibreOffice Help: Floor functions — contrast with FLOOR.PRECISE.