How to Use the ROUNDDOWN Function in Excel

Excel's ROUNDDOWN function reduces a number's precision by rounding it toward zero. It is useful when you need to discard extra decimal places without allowing the result's absolute value to increase.

ROUNDDOWN syntax

=ROUNDDOWN(number, num_digits)

• number: the value or cell reference to round.
• num_digits: the number of digits to keep. Use 0 for an integer, a positive number for decimal places, or a negative number to round digits to the left of the decimal point.

ROUNDDOWN always moves toward zero. For a positive number, the result is smaller; for a negative number, it is less negative. This distinction matters because “round down” can otherwise be mistaken for rounding toward negative infinity.

Basic examples

If the source number is in cell C6, enter =ROUNDDOWN(C6,0) to return its integer portion. Depending on regional settings, Excel may use semicolons between arguments and a comma as the decimal separator.

When to use ROUNDDOWN

Use ROUNDDOWN when the rule explicitly requires digits to be discarded toward zero—for example, limiting a calculated quantity to whole units. Do not assume it is appropriate for financial or tax calculations: those processes may require a prescribed rounding method.

ROUNDDOWN changes the value used in later calculations. If you only want fewer decimals to appear on screen, change the cell's number format instead. For standard nearest-value rounding, use ROUND; to force rounding away from zero, use ROUNDUP.

ROUNDDOWN compared with TRUNC

With num_digits supplied, ROUNDDOWN and TRUNC commonly return the same result because both move toward zero. TRUNC defaults to zero decimal places when its second argument is omitted. See the Excel TRUNC function guide for examples. If rounding is part of a matching workflow, review these tips for matching values in Excel as well.

Common mistakes

• Using text that Excel cannot interpret as a number produces #VALUE!.
• Positive num_digits values keep decimal places; negative values round tens, hundreds, and larger positions.
• ROUNDDOWN returns a numeric value, so its result can be used directly in other formulas.