INT Function

All versions Math & Trig

The Excel INT function rounds a number down to the nearest integer — always toward negative infinity, which trips people up with negative numbers.

Quick answer:

=INT(5.9) rounds down = 5

Syntax

=INT(number)

Argument		Description
`number`	Required	The number you want to round down to the nearest integer.

How to use it

INT always rounds down toward negative infinity — it does not simply chop off decimals:

=INT(5.9) // down = 5

=INT(-5.1) // down (more negative) = -6

=INT(8) // already an integer = 8

For positive numbers INT and TRUNC give the same answer. For negatives they split: INT rounds down (so -5.1 → -6), while TRUNC just drops the decimals toward zero (so -5.1 → -5).

INT ≠ “drop the decimals.” For negatives INT goes the other way: =INT(-5.1) is -6, not -5. Use TRUNC if you want to truncate toward zero.

Try it: interactive demo

Live demo

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example

Result:

Practice workbook

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Frequently asked questions

What's the difference between INT and TRUNC?

For positives they match. For negatives INT rounds down toward negative infinity (-5.1 → -6) while TRUNC simply drops the decimals toward zero (-5.1 → -5).

Does INT round or truncate?

It rounds down (toward negative infinity). That looks like truncation for positive numbers, but for negatives it rounds away from zero.

Why does INT(-5.1) return -6?

Because INT always rounds toward negative infinity, and -6 is below -5.1. To keep -5 instead, use =TRUNC(-5.1).

How do I get just the decimal (fractional) part?

Subtract INT from the number for positives: =A1-INT(A1). For mixed signs, =A1-TRUNC(A1) keeps the sign of the fraction consistent.

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Related functions: TRUNC · ROUNDDOWN · FLOOR · ROUND · MROUND