Rounding Numbers

PHP has three main rounding functions.

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<?php
echo round(4.4) . "\n";
echo round(4.5) . "\n";
echo floor(4.9) . "\n";
echo ceil(4.1);

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4

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4
5

round(4.5) goes up. By default, PHP rounds halves away from zero, so -4.5 becomes -5.

Decimal places

The second argument is how many decimals to keep.

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<?php
echo round(3.14159, 2) . "\n";
echo round(2.5, 0) . "\n";
echo round(1234.5678, 1);

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3.14
3
1234.6

Negative precision

A negative number rounds to tens, hundreds and so on.

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<?php
echo round(1234, -1) . "\n";
echo round(1234, -2) . "\n";
echo round(1950, -2);

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1230
1200
2000

Return type is a float

round(), floor() and ceil() all return a float, even for a whole number. Use a cast or intval() if you need an integer.

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<?php
var_dump(round(5.2));
var_dump((int) round(5.2));

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float(5)
int(5)

Rounding modes

By default, halves round away from zero. You can ask for other behaviour with a third argument.

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<?php
echo round(2.5, 0, PHP_ROUND_HALF_EVEN) . "\n";   // banker's rounding
echo round(3.5, 0, PHP_ROUND_HALF_EVEN) . "\n";
echo round(2.5, 0, PHP_ROUND_HALF_DOWN);

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2

PHP 8.4 adds a RoundingMode enum with more modes, such as RoundingMode::TowardsZero. On older versions, use the PHP_ROUND_* constants.

Page counts: ceil()

How many pages for 47 results, 10 per page? You need to round up.

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<?php
$results = 47;
$perPage = 10;

echo ceil($results / $perPage);

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5

Displaying vs calculating

Rounding changes the stored value. If you only want to show two decimals, use number_format() and keep the full number for calculations. See Number Formatting.