Excel ROUNDDOWN Function

ROUNDDOWN rounds a positive number down to the precision you choose or a negative number up to the precision you choose.

Use it when extra precision should be discarded such as for computing completed units, capped rates, or conservative estimates.

Choose the number Use a value, cell, or formula result

Choose the rounding place Decimals, whole numbers, tens, hundreds, etc.

Discard the rest Positive numbers step down; negatives step up closer to zero

ROUNDDOWN syntax & arguments

Syntax

=ROUNDDOWN(number, num_digits)

Required Optional

1

number
Required

The number, cell reference, or formula result to trim at the chosen decimal or place value.
2

num_digits
Required

The number of digits or places to keep. Positive num_digits values keep that many decimal places, so 2 changes 12.987 to 12.98 and -12.987 to -12.98. 0 keeps no decimal places, so 12.987 becomes 12 and -12.987 becomes -12. Negative num_digits values work left of the decimal. -1 rounds to a multiple of 10, -2 rounds to a multiple of 100 and so on. For example, num_digits of -1 turns 129 to 120 and -129 to -120.

Example

=ROUNDDOWN(B2, 2)

Round B2 two decimal places towards 0 and drop any later decimals.

ROUNDDOWN caveats

Negative numbers actually round up moving closer to zero

ROUNDDOWN rounds negative numbers up instead of down, which may not be intuitive given the function's name. For instance, =ROUNDDOWN(-9.87,1) returns -9.8, not -9.9.
Negative num_digits uses place values

A num_digits of -1 rounds positive numbers down to the next lower multiple of 10 and negative numbers up to the next higher multiple of 10 while a num_digits of -2 rounds positive numbers down to the next lower multiple of 100 and negative numbers up to the next higher multiple of 100 and so on. So for instance, =ROUNDDOWN(987,-2) returns 900 and =ROUNDDOWN(-987,-2) returns -900.
It does not choose the nearest value

=ROUNDDOWN(2.9,0) returns 2, not the nearest whole number 3. The digit after the chosen place is discarded, even when it is 5 or higher.

Need alternative rounding? Use ROUND when values should go to the nearest result, or ROUNDUP when positive numbers should round up and negative numbers should round down.