round

(PHP 4, PHP 5, PHP 7)

round — Arrondit un nombre à virgule flottante

Description

float round ( float $val [, int $precision = 0 [, int $mode = PHP_ROUND_HALF_UP ]] )

Retourne la valeur arrondie de val à la précision precision (nombre de chiffres après la virgule). Le paramètre precision peut être négatif ou NULL : c'est sa valeur par défaut.

Note: PHP ne gère pas correctement les chaînes telles que "12 300,2", par défaut. Reportez-vous à la conversion de chaînes.

Liste de paramètres

val

La valeur à arrondir

precision

Le nombre optionnel de décimales à arrondir.

mode

Utilisez une des constantes suivantes pour spécifier le mode d'arrondi.

Constante	Description
`PHP_ROUND_HALF_UP`	Arrondit `val` à une précision `precision` supérieure de décimal en s'éloignant de zéro lorsqu'il est à mi-chemin. Par exemple, 1.5 deviendra 2 et -1.5 deviendra -2.
`PHP_ROUND_HALF_DOWN`	Arrondit `val` à une précision `precision` inférieure de décimal en s'approchant de zéro lorsqu'il est à mi-chemin. Par exemple, 1.5 deviendra 1 et -1.5 deviendra -1.
`PHP_ROUND_HALF_EVEN`	Arrondit `val` à la précision `precision` de décimal vers la prochaine valeur paire.
`PHP_ROUND_HALF_ODD`	Arrondit `val` à la précision `precision` de décimal vers la prochaine valeur impaire.

Valeurs de retour

La valeur arrondie

Exemples

Exemple #1 Exemple avec round()


<?php
echo round(3.4);         // 3
echo round(3.5);         // 4
echo round(3.6);         // 4
echo round(3.6, 0);      // 4
echo round(1.95583, 2);  // 1.96
echo round(1241757, -3); // 1242000
echo round(5.045, 2);    // 5.05
echo round(5.055, 2);    // 5.06
?>

Exemple #2 Exemple avec le paramètre mode


<?php
echo round(9.5, 0, PHP_ROUND_HALF_UP);   // 10
echo round(9.5, 0, PHP_ROUND_HALF_DOWN); // 9
echo round(9.5, 0, PHP_ROUND_HALF_EVEN); // 10
echo round(9.5, 0, PHP_ROUND_HALF_ODD);  // 9

echo round(8.5, 0, PHP_ROUND_HALF_UP);   // 9
echo round(8.5, 0, PHP_ROUND_HALF_DOWN); // 8
echo round(8.5, 0, PHP_ROUND_HALF_EVEN); // 8
echo round(8.5, 0, PHP_ROUND_HALF_ODD);  // 9
?>

Exemple #3 Exemple avec les paramètres mode et precision


<?phpe
/* Utilisation de PHP_ROUND_HALF_UP avec une précision d'une décimale */
echo round( 1.55, 1, PHP_ROUND_HALF_UP);   //  1.6
echo round( 1.54, 1, PHP_ROUND_HALF_UP);   //  1.5
echo round(-1.55, 1, PHP_ROUND_HALF_UP);   // -1.6
echo round(-1.54, 1, PHP_ROUND_HALF_UP);   // -1.5

/* Utilisation de PHP_ROUND_HALF_DOWN avec une précision d'une décimale */
echo round( 1.55, 1, PHP_ROUND_HALF_DOWN); //  1.5
echo round( 1.54, 1, PHP_ROUND_HALF_DOWN); //  1.5
echo round(-1.55, 1, PHP_ROUND_HALF_DOWN); // -1.5
echo round(-1.54, 1, PHP_ROUND_HALF_DOWN); // -1.5

/* Utilisation de PHP_ROUND_HALF_EVEN avec une précision d'une décimale */
echo round( 1.55, 1, PHP_ROUND_HALF_EVEN); //  1.6
echo round( 1.54, 1, PHP_ROUND_HALF_EVEN); //  1.5
echo round(-1.55, 1, PHP_ROUND_HALF_EVEN); // -1.6
echo round(-1.54, 1, PHP_ROUND_HALF_EVEN); // -1.5

/* Utilisation de PHP_ROUND_HALF_ODD avec une précision d'une décimale */
echo round( 1.55, 1, PHP_ROUND_HALF_ODD);  //  1.5
echo round( 1.54, 1, PHP_ROUND_HALF_ODD);  //  1.5
echo round(-1.55, 1, PHP_ROUND_HALF_ODD);  // -1.5
echo round(-1.54, 1, PHP_ROUND_HALF_ODD);  // -1.5
?>

Historique

Version	Description
5.3.0	Le paramètre `mode` a été ajouté.
5.2.7	Le fonctionnement interne de round() a été modifié afin d'être conforme au standard C99.

Voir aussi

ceil() - Arrondit au nombre supérieur
floor() - Arrondit à l'entier inférieur
number_format() - Formate un nombre pour l'affichage

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User Contributed Notes 30 notes

down

172

takingsides at gmail dot com ¶

3 years ago


In my opinion this function lacks two flags:

- PHP_ROUND_UP - Always round up.
- PHP_ROUND_DOWN - Always round down.

In accounting, it's often necessary to always round up, or down to a precision of thousandths.

<?php
function round_up($number, $precision = 2)
{
    $fig = (int) str_pad('1', $precision, '0');
    return (ceil($number * $fig) / $fig);
}

function round_down($number, $precision = 2)
{
    $fig = (int) str_pad('1', $precision, '0');
    return (floor($number * $fig) / $fig);
}
?>

down

depaula at unilogica dot com ¶

6 months ago


As PHP doesn't have a a native number truncate function, this is my solution - a function that can be usefull if you need truncate instead round a number.

<?php
/**
 * Truncate a float number, example: <code>truncate(-1.49999, 2); // returns -1.49
 * truncate(.49999, 3); // returns 0.499
 * </code>
 * @param float $val Float number to be truncate
 * @param int f Number of precision
 * @return float
 */
function truncate($val, $f="0")
{
    if(($p = strpos($val, '.')) !== false) {
        $val = floatval(substr($val, 0, $p + 1 + $f));
    }
    return $val;
}
?>

Originally posted in http://stackoverflow.com/a/12710283/1596489

down

slimusgm at gmail dot com ¶

2 years ago


If you have negative zero and you need return positive number simple add +0:

$number = -2.38419e-07;
var_dump(round($number,1));//float(-0)
var_dump(round($number,1) + 0);//float(0)

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djcox99 at googlemail dot com ¶

3 years ago


I discovered that under some conditions you can get rounding errors with round when converting the number to a string afterwards.

To fix this I swapped round() for number_format().

Unfortunately i cant give an example (because the number cant be represented as a string !)

essentially I had round(0.688888889,2);

which would stay as 0.68888889 when printed as a string.

But using number_format it correctly became 0.69.

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jongbumi at gmail dot com ¶

1 year ago


PHP 5.3, 5.4, 5.5
<?php
$fInfinty = pow(1000, 1000); // float(INF)
$fResult = round(123.456, $fInfinty); // double(123)
?>

PHP 5.6
<?php
$fInfinty = pow(1000, 1000); // float(INF)
$fResult = round(123.456, $fInfinty); // float(0)
?>

PHP 7
<?php
$fInfinty = pow(1000, 1000); // float(INF)
$fResult = round(123.456, $fInfinty); // null
?>

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craft at ckdevelop dot org ¶

3 years ago


function mround($val, $f=2, $d=6){
    return sprintf("%".$d.".".$f."f", $val);
}

echo mround(34.89999);  //34.90

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twan at ecreation dot nl ¶

17 years ago


If you'd only want to round for displaying variables (not for calculating on the rounded result) then you should use printf with the float:



<?php printf ("%6.2f",3.39532); ?>



This returns: 3.40 .

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martinr at maarja dot net ¶

9 years ago


Please note that the format of this functions output also depends on your locale settings. For example, if you have set your locale to some country that uses commas to separate decimal places, the output of this function also uses commas instead of dots.

This might be a problem when you are feeding the rounded float number into a database, which requires you to separate decimal places with dots.

See it in action:
<?php
    echo round('3.5558', 2);
    setlocale(constant('LC_ALL'), 'et_EE.UTF-8');
    echo '<br />'. round('3.5558', 2);
?>

The output will be:
3.56
3,56

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Anonymous ¶

6 years ago


Here is function that rounds to a specified increment, but always up. I had to use it for price adjustment that always went up to $5 increments.



<?php  

function roundUpTo($number, $increments) {

    $increments = 1 / $increments;

    return (ceil($number * $increments) / $increments);

}

?>

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php at silisoftware dot com ¶

14 years ago


Here's a function to round to an arbitary number of significant digits. Don't confuse it with rounding to a negative precision - that counts back from the decimal point, this function counts forward from the Most Significant Digit.



ex:



<?php

round(1241757, -3); // 1242000

RoundSigDigs(1241757, 3); // 1240000

?>



Works on negative numbers too. $sigdigs should be >= 0



<?php

function RoundSigDigs($number, $sigdigs) {

    $multiplier = 1;

    while ($number < 0.1) {

        $number *= 10;

        $multiplier /= 10;

    }

    while ($number >= 1) {

        $number /= 10;

        $multiplier *= 10;

    }

    return round($number, $sigdigs) * $multiplier;

}

?>

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serg at kalachev dot ru ¶

2 years ago


Excel-like ROUNDUP function:

public static function round_up($value, $places) 
{
    $mult = pow(10, abs($places)); 
     return $places < 0 ?
    ceil($value / $mult) * $mult :
        ceil($value * $mult) / $mult;
}

echo round_up(12345.23, 1); // 12345.3
echo round_up(12345.23, 0); // 12346 
echo round_up(12345.23, -1); // 12350 
echo round_up(12345.23, -2); // 12400 
echo round_up(12345.23, -3); // 13000 
echo round_up(12345.23, -4); // 20000

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dastra ¶

5 years ago


round() will sometimes return E notation when rounding a float when the amount is small enough - see  https://bugs.php.net/bug.php?id=44223 .  Apparently it's a feature.

To work around this "feature" when converting to a string, surround your round statement with an sprintf:

sprintf("%.10f", round( $amountToBeRounded, 10));

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christian at deligant dot net ¶

5 years ago


this function (as all mathematical operators) takes care of the setlocale setting, resulting in some weirdness when using the result where the english math notation is expected, as the printout of the result in a width: style attribute!



<?php

$a=3/4;

echo round($a, 2); // 0.75



setlocale(LC_ALL, 'it_IT@euro', 'it_IT', 'it');

$b=3/4;

echo round($b,2); // 0,75

?>

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esion99 at gmail dot com ¶

3 years ago


Unexpected result or misunderstanding (php v5.5.9)

<?php

echo round(1.55, 1, PHP_ROUND_HALF_DOWN); // 1.5
echo round(1.551, 1, PHP_ROUND_HALF_DOWN); //1.6

?>

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Anonymous ¶

8 months ago


Note that PHP 5.3 didn't just introduce $mode, it rewrote the rounding implementation completely to eliminate many kinds of rounding errors common to rounding floating point values.

That's why round() gives you the correct result even when floor/ceil don't.
For example,  floor(0.285 * 100 + 0.5) VS round(0.285*100 + 0.5). First one gives 28, second one gives 29.

More details here: https://wiki.php.net/rfc/rounding

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greghenle at gmail dot com ¶

7 months ago


/**
 * Round to first significant digit
 * +N to +infinity
 * -N to -infinity
 *
 */
function round1stSignificant ( $N ) {
  if ( $N === 0 ) {
    return 0;
  }

  $x = floor ( log10 ( abs( $N ) ) );

  return ( $N > 0 )
    ? ceil( $N * pow ( 10, $x * -1 ) ) * pow( 10, $x )
    : floor( $N * pow ( 10, $x * -1 ) ) * pow( 10, $x );
}

echo round1stSignificant( 39144818 ) . PHP_EOL;
echo round1stSignificant( 124818 ) . PHP_EOL;
echo round1stSignificant( 0.07468 ) . PHP_EOL;
echo round1stSignificant( 0 ) . PHP_EOL;
echo round1stSignificant( -0.07468 ) . PHP_EOL;

/**
 * Output
 * 
 * 40000000
 * 200000
 * 0.08
 * 0
 * -0.08
 * 
 */

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feha at vision dot to ¶

6 years ago


Here is a short neat function to round minutes (hour) ...

<?php

function minutes_round ($hour = '14:03:32', $minutes = '5', $format = "H:i")
{
    // by Femi Hasani [www.vision.to]
    $seconds = strtotime($hour);
    $rounded = round($seconds / ($minutes * 60)) * ($minutes * 60);
    return date($format, $rounded);
}

?>

You decide to round to nearest minute ...
example will produce : 14:05

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michaeldnelson dot mdn at gmail dot com ¶

7 years ago


This function will let you round to an arbitrary non-zero number.  Zero of course causes a division by zero.



<?php

function roundTo($number, $to){

    return round($number/$to, 0)* $to;

}



echo roundTo(87.23, 20); //80

echo roundTo(-87.23, 20); //-80

echo roundTo(87.23, .25); //87.25

echo roundTo(.23, .25); //.25

?>

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-1

spectrumcat at gmail dot com ¶

3 years ago


In case someone will need a "graceful" rounding (that changes it's precision to get a non 0 value) here's a simple function:

function gracefulRound($val, $min = 2, $max = 4) {
    $result = round($val, $min);
    if ($result == 0 && $min < $max) {
        return gracefulRound($val, ++$min, $max);
    } else {
        return $result;
    }
}

Usage:
$_ = array(0.5, 0.023, 0.008, 0.0007, 0.000079, 0.0000048);
foreach ($_ as $val) {
    echo "{$val}: ".gracefulRound($val)."\n";
}

Output:
0.5: 0.5
0.023: 0.02
0.008: 0.01
0.0007: 0.001
0.000079: 0.0001
0.0000048: 0

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-2

omnibus at omnibus dot edu dot pl ¶

6 years ago


Beware strange behaviour if number is negative and precision is bigger than the actual number of digits after comma.

round(-0.07, 4);

returns

-0.07000000000000001

So if you validate it against a regular expression requiring the maximum amount of digits after comma, you'll get into trouble.

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-1

Anonymous ¶

7 years ago


This functions return ceil($nb) if the double or float value is bigger than "$nb.5" else it's return floor($nb)



<?php

    function arounds_int($nb) {

     

        if(!is_numeric($nb)) {

            return false;

        }

        

        $sup = round($nb);

        $inf = floor($nb);

        $try = (double) $inf . '.5' ; 

        

        if($nb > $try) {

            return $sup;

        }

        

        return $inf;

    }

?>

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-2

terry at scribendi dot com ¶

13 years ago


To round any number to a given number of significant digits, use log10 to find out its magnitude:



<?php round($n, ceil(0 - log10($n)) + $sigdigits); ?>



Or when you have to display a per-unit price which may work out to be less than a few cents/pence/yen you can use:



<?php

// $exp = currency decimal places - 0 for Yen/Won, 2 for most others

$dp = ceil(0 - log10($n)) + $sigdigits;

$display = number_format($amount, ($exp>$dp)?$exp:$dp);

?>



This always displays at least the number of decimal places required by the currency, but more if displaying the unit price with precision requires it - eg: 'English proofreading from $0.0068 per word', 'English beer from $6.80 per pint'.

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-4

lossantis at ig dot com dot br ¶

7 years ago


Since the mode parameter for options like PHP_ROUND_HALF_UP is available as of PHP 5.3, here is an alternative for ceiling:



<?php echo 252 / 40; // 6.3 ?>



If I round this:



<?php echo round(252 / 40); // 6 ?>



You can also use a ceil (which might be useful for pagination):



<?php echo ceil(252/40); // 7 ?>



[Edited by: googleguy@php.net for clarity]

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-6

tom at crysis-online dot com ¶

10 years ago


I just found out then that even if you round a double (3.7) to an integer (4), it's data type remains as 'double'. So it's always good to use the settype() function when using the round() function to prevent any problems with your scripts.

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-5

tichoux at charlevoix dot net ¶

14 years ago


for a poll, if you want to have 100% and not 99 or 99.99 % you can do that :



<?php

round( number_format( (($individual_result*100)/$total_result), 2), 1);

?>

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-5

Bevan ¶

7 years ago


Formats a number to the specified number of significant figures.

<?php
/**
 * Formats numbers to the specified number of significant figures.
 *
 * @author Bevan Rudge, Drupal.geek.nz
 *
 * @param number $number
 *   The number to format.
 * @param integer $sf
 *   The number of significant figures to round and format the number to.
 * @return string
 *   The rounded and formatted number.
 */
function format_number_significant_figures($number, $sf) {
  // How many decimal places do we round and format to?
  // @note May be negative.
  $dp = floor($sf - log10(abs($number)));
  // Round as a regular number.
  $number = round($number, $dp);
  // Leave the formatting to format_number(), but always format 0 to 0dp.
  return number_format($number, 0 == $number ? 0 : $dp);
}
?>

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-5

ianring (at) golden.net ¶

13 years ago


The round() function may indeed work properly with half-values (eg. 1.5), but this little method will give you peace of mind. Add some "fuzz" to your function with a miniscule delta value.



<?php

$delta = 0.00001;

$x = round($x+$delta);

?>



This is fine, unless $x has a value of 1.49999 ... if you worried about that, use this method instead:



<?php

if(($x-floor($x))==0.5){

   $x+=$delta;

}

$x = round($x);

?>



you can change your "optimistic" delta into a "pessimistic" delta by subtracting instead of adding.



Cheers,

Ian Ring

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-8

hugues at zonereseau dot com ¶

7 years ago


I had problem with round() function I didn't gave me the same result in windows or on a linux server :



<?php

round(4.725, 2); // gave me 4.72 on linux

round(4.725, 2); // gave me 4.73 on windows

?>



The expected result was 4.73



Here my function to resolve my problem



<?php

function mround($number, $precision=0) {

    

    $precision = ($precision == 0 ? 1 : $precision);    

    $pow = pow(10, $precision);

    

    $ceil = ceil($number * $pow)/$pow;

    $floor = floor($number * $pow)/$pow;

    

    $pow = pow(10, $precision+1);

    

    $diffCeil     = $pow*($ceil-$number);

    $diffFloor     = $pow*($number-$floor)+($number < 0 ? -1 : 1);

    

    if($diffCeil >= $diffFloor) return $floor;

    else return $ceil;

}



echo mround(4.725, 2); // Yes 4.73

?>

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-3

php at persignum dot com ¶

1 year ago


Because this function is missing round up and round down constants and the top note doesn't really show you how to round up or down to the nearest number, here is an easy way to always round up or always round down to the nearest number.

int is the number you want to round

n is the nearest number you want rounded to.

Round up to the nearest number

function round_up($int, $n) {
    return ceil($int / $n) * $n;
}

And to round down to the nearest number

function round_down(int, $n) {
    return floor($int / $n) * $n;
}

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-9

maxteiber at gmail dot com ¶

10 years ago


the result of this function always depends on the underlying C function. There have been a lot of compiler bugs and floating-point precission problems involving this function. Right now the following code:

<?php
echo round(141.075, 2);
?>

returns:

141.07

on my machine.
So never really trust this function when you do critical calculations like accounting stuff!
Instead: use only integers or use string comparisons.

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