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    round

    (PHP 4, PHP 5, PHP 7, PHP 8)

    round — Rundet einen Gleitkommawert

    Beschreibung

    round(int|float $num, int $precision = 0, int $mode = PHP_ROUND_HALF_UP): float

    Rundet den Parameter num auf die mit precision angegebene Anzahl von Nachkommastellen. precision kann dabei auch Null (Vorgabewert) oder negativ sein. So wird bei einer Stellenzahl von -1 z. B. auf volle Zehner gerundet.

    Parameter-Liste

    num

    Der zu rundende Wert.

    precision

    Auf wie viele Nachkommastellen gerundet werden soll.

    Ist die Genauigkeit precision positiv, wird num auf precision signifikante Stellen nach dem Dezimalpunkt gerundet.

    Ist die Genauigkeit precision negativ, wird num auf precision signifikante Stellen vor dem Dezimalpunkt gerundet, d. h. auf das nächste Vielfache von pow(10, -precision), z. B. wird num mit einer precision von -1 auf Zehner gerundet, mit einer precision von -2 auf Hunderter usw.

    mode

    Eine der folgenden Konstanten kann verwendet werden, um den Rundungsmodus festzulegen.

    Konstanten Beschreibung
    PHP_ROUND_HALF_UP Rundet num auf halber Strecke von Null weg, womit 1.5 zu 2 wird und -1.5 zu -2.
    PHP_ROUND_HALF_DOWN Rundet num auf halber Strecke zu Null hin, womit 1.5 zu 1 wird und -1.5 zu -1.
    PHP_ROUND_HALF_EVEN Rundet num auf halber Strecke auf den nächsten geraden Wert, womit sowohl 1.5 als auch 2.5 zu 2 werden.
    PHP_ROUND_HALF_ODD Rundet num auf halber Strecke auf den nächsten ungeraden Wert, womit 1.5 zu 1 wird und 2.5 zu 3.

    Rückgabewerte

    Der auf die angegebene precision gerundete Wert als Float.

    Changelog

    Version Beschreibung
    8.0.0 num akzeptiert keine internen Objekte mehr, die eine numerische Konvertierung unterstützen.

    Beispiele

    Beispiel #1 round()-Beispiele

    <?php
    var_dump    (round(3.4));
    var_dump(round(3.5));
    var_dump(round(3.6));
    var_dump(round(3.6, 0));
    var_dump(round(5.045, 2));
    var_dump(round(5.055, 2));
    var_dump(round(345, -2));
    var_dump(round(345, -3));
    var_dump(round(678, -2));
    var_dump(round(678, -3));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    float(3)
float(4)
float(4)
float(4)
float(5.05)
float(5.06)
float(300)
float(0)
float(700)
float(1000)

    Beispiel #2 Wie precision eine Gleitkommazahl betrifft

    <?php
    $number     = 135.79;

    var_dump(round($number, 3));
    var_dump(round($number, 2));
    var_dump(round($number, 1));
    var_dump(round($number, 0));
    var_dump(round($number, -1));
    var_dump(round($number, -2));
    var_dump(round($number, -3));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    float(135.79)
float(135.79)
float(135.8)
float(136)
float(140)
float(100)
float(0)

    Beispiel #3 mode-Beispiele

    <?php
    echo 'Rundundsmodi mit 9.5' . PHP_EOL;
    var_dump(round(9.5, 0, PHP_ROUND_HALF_UP));
    var_dump(round(9.5, 0, PHP_ROUND_HALF_DOWN));
    var_dump(round(9.5, 0, PHP_ROUND_HALF_EVEN));
    var_dump(round(9.5, 0, PHP_ROUND_HALF_ODD));

    echo     PHP_EOL;
    echo     'Rundundsmodi mit 8.5' . PHP_EOL;
    var_dump(round(8.5, 0, PHP_ROUND_HALF_UP));
    var_dump(round(8.5, 0, PHP_ROUND_HALF_DOWN));
    var_dump(round(8.5, 0, PHP_ROUND_HALF_EVEN));
    var_dump(round(8.5, 0, PHP_ROUND_HALF_ODD));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    Rundundsmodi mit 9.5
float(10)
float(9)
float(10)
float(9)

Rundundsmodi mit 8.5
float(9)
float(8)
float(8)
float(9)

    Beispiel #4 Beispiele für mode mit precision

    <?php
    echo 'Verwendung von PHP_ROUND_HALF_UP mit einer Dezimalstelle Genauigkeit' . PHP_EOL;
    var_dump(round( 1.55, 1, PHP_ROUND_HALF_UP));
    var_dump(round(-1.55, 1, PHP_ROUND_HALF_UP));

    echo     PHP_EOL;
    echo     'Verwendung von PHP_ROUND_HALF_DOWN mit einer Dezimalstelle Genauigkeit' . PHP_EOL;
    var_dump(round( 1.55, 1, PHP_ROUND_HALF_DOWN));
    var_dump(round(-1.55, 1, PHP_ROUND_HALF_DOWN));

    echo     PHP_EOL;
    echo     'Verwendung von PHP_ROUND_HALF_EVEN mit einer Dezimalstelle Genauigkeit' . PHP_EOL;
    var_dump(round( 1.55, 1, PHP_ROUND_HALF_EVEN));
    var_dump(round(-1.55, 1, PHP_ROUND_HALF_EVEN));

    echo     PHP_EOL;
    echo     'Verwendung von PHP_ROUND_HALF_ODD mit einer Dezimalstelle Genauigkeit' . PHP_EOL;
    var_dump(round( 1.55, 1, PHP_ROUND_HALF_ODD));
    var_dump(round(-1.55, 1, PHP_ROUND_HALF_ODD));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    Verwendung von PHP_ROUND_HALF_UP mit einer Dezimalstelle Genauigkeit
float(1.6)
float(-1.6)

Verwendung von PHP_ROUND_HALF_DOWN mit einer Dezimalstelle Genauigkeit
float(1.5)
float(-1.5)

Verwendung von PHP_ROUND_HALF_EVEN mit einer Dezimalstelle Genauigkeit
float(1.6)
float(-1.6)

Verwendung von PHP_ROUND_HALF_ODD mit einer Dezimalstelle Genauigkeit
float(1.5)
float(-1.5)

    Siehe auch

    add a note add a note

    User Contributed Notes 32 notes

    up
    315
    takingsides at gmail dot com
    10 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);
    }
    ?>
    up
    33
    depaula at unilogica dot com
    7 years 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
    up
    2
    Anonymous
    8 years 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
    up
    29
    slimusgm at gmail dot com
    10 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)
    up
    13
    serg at kalachev dot ru
    10 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
    up
    7
    Mojo urk
    6 years ago
    Solving round_down() problem:
    -----------------------------
    Use of <?php floor(pow(10, $precision) * $value) / pow(10, $precision); ?> fails in some cases, e.g. round_down(2.05, 2) gives incorrect 2.04.
    Here is a "string" solution (https://stackoverflow.com/a/26491492/1245149) of the problem (a negative precision is not covered):

    <?php
    function round_down($value, $precision) {       
            $value = (float)$value;
            $precision = (int)$precision;
        if (    $precision < 0) {
                $precision = 0;
        }
            $decPointPosition = strpos($value, '.');
        if (    $decPointPosition === false) {
            return     $value;
        }
        return (float)(    substr($value, 0, $decPointPosition + $precision + 1));       
    }
    ?>

    Solving round_up() problem:
    ---------------------------
    Use of <?php ceil(pow(10, $precision) * $value) / pow(10, $precision);?> fails in some cases, e.g. round_up(2.22, 2) gives incorrect 2.23 (https://stackoverflow.com/a/8239620/1245149).
    Adapting the above round_down() "string" solution I have got this result (a negative precision is not covered):

    <?php
    function round_up($value, $precision) {       
            $value = (float)$value;
            $precision = (int)$precision;
        if (    $precision < 0) {
                $precision = 0;
        }
            $decPointPosition = strpos($value, '.');
        if (    $decPointPosition === false) {
            return     $value;
        }
            $floorValue = (float)(substr($value, 0, $decPointPosition + $precision + 1));
            $followingDecimals = (int)substr($value, $decPointPosition + $precision + 1);
        if (    $followingDecimals) {
                $ceilValue = $floorValue + pow(10, -$precision); // does this give always right result?
            }
        else {
                $ceilValue = $floorValue;
        }
        return     $ceilValue;               
    }
    ?>

    I don't know it is bulletproof, but at least it removes the above mentioned fail. I have done no binary-to-decimal-math-analysis but if `$floorValue + pow(10, 0 - $precision)` works
    always as expected then it should be ok.
    up
    21
    djcox99 at googlemail dot com
    10 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.
    up
    10
    craft at ckdevelop dot org
    10 years ago
    function mround($val, $f=2, $d=6){
        return sprintf("%".$d.".".$f."f", $val);
    }

    echo mround(34.89999);  //34.90
    up
    11
    jongbumi at gmail dot com
    8 years 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
    ?>
    up
    18
    esion99 at gmail dot com
    10 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

    ?>
    up
    10
    christian at deligant dot net
    13 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
    ?>
    up
    19
    twan at ecreation dot nl
    24 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 .
    up
    18
    Anonymous
    14 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);
    }
    ?>
    up
    8
    michaeldnelson dot mdn at gmail dot com
    15 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
    ?>
    up
    4
    greghenle at gmail dot com
    7 years 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
    *
    */
    up
    9
    martinr at maarja dot net
    16 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
    up
    4
    dastra
    12 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));
    up
    9
    php at silisoftware dot com
    22 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;
    }
    ?>
    up
    2
    goreyshi at gmail dot com
    6 years ago
    When you have a deal with money like dollars, you need to display it under this condition:
    -format all number with two digit decimal for cents.
    -divide 1000 by ,
    -round half down for number with more than two decimal

    I approach it using round function inside the number_format function:

    number_format((float)round( 625.371 ,2, PHP_ROUND_HALF_DOWN),2,'.',',')  // 625.37
    number_format((float)round( 625.379 ,2, PHP_ROUND_HALF_DOWN),2,'.',',')  // 625.38
    number_format((float)round( 1211.20 ,2, PHP_ROUND_HALF_DOWN),2,'.',',')  // 1,211.20
    number_format((float)round( 625 ,2, PHP_ROUND_HALF_DOWN),2,'.',',')      // 625.00
    up
    0
    Hayley Watson
    5 years ago
    It should just be noted that what is called "precision" on this page is more correctly called accuracy; precision is the total number of significant digits on both sides of the decimal point, while accuracy is the number of digits to the right of the point. It's a common confusion.
    up
    1
    feha at vision dot to
    14 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
    up
    -2
    omnibus at omnibus dot edu dot pl
    14 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.
    up
    -1
    Astro
    4 years ago
    Okay, final version of my function:

    function NumberPrecision($n, $precision=0, $is_round=true)
                {
                if ($is_round)
                    {
                    $r = 5 * pow(10, -($precision+1));
                    $n += (($n < 0) ? -$r : $r);
                    }
               
                $comma = '.';
               
                $r = 5 * pow(10, -($precision+2));
                $n += (($n > 0) ? -$r : $r);
                $n = number_format($n, $precision+1, $comma, '');
               
                $n .= $comma;
                list($n, $frac) = explode($comma, $n, 2);
                $n = rtrim(rtrim($n, $comma) . $comma . substr($frac, 0, $precision), $comma);
                return ($n);
                }

    It can be useful in come cases when built-in function like round() or number_format() returns unexpected results. Works with positive and negative numbers, zero, numbers like 1/12, 0.3, numbers in scientific notation etc.
    up
    -1
    terry at scribendi dot com
    20 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 $6.80 per pint'.
    up
    -2
    Anonymous
    15 years ago
    This functions return ceil($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;
        }
    ?>
    up
    -3
    spectrumcat at gmail dot com
    10 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
    up
    -4
    maxteiber at gmail dot com
    18 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.
    up
    -4
    Anonymous
    7 years ago
    This function has strange. behaviors:

    <?php
    echo round(0.045, 2);      // 0.05
    echo round(0.45, 1);      // 0.5
    echo round(1.045-1, 2);    // 0.04 !!!
    echo round(1.45-1, 1);      // 0.5
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    -7
    lossantis at ig dot com dot br
    14 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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    -5
    php at persignum dot com
    9 years 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;
    }
    up
    -11
    Bevan
    15 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);
    }
    ?>
    up
    -10
    armanhakimsagar at gmail dot com
    7 years ago
    $a = .9;

        $b = .8;

        $d = .1;

        $e = .2;

        $x = $a-$b;

        $y = $e-$d;

        $f = round($x,2);

        echo $f;

        if($f==$y){

            echo "ok";
        }
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