Last 5.3 release ever available: PHP 5.3.29 - 5.3 now EOL

round

(PHP 4, PHP 5)

roundRounds a float

Description

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

Returns the rounded value of val to specified precision (number of digits after the decimal point). precision can also be negative or zero (default).

Note: PHP doesn't handle strings like "12,300.2" correctly by default. See converting from strings.

Parameters

val

The value to round

precision

The optional number of decimal digits to round to.

mode

One of PHP_ROUND_HALF_UP, PHP_ROUND_HALF_DOWN, PHP_ROUND_HALF_EVEN, or PHP_ROUND_HALF_ODD.

Return Values

The rounded value

Examples

Example #1 round() examples

<?php
echo round(3.4);         // 3
echo round(3.5);         // 4
echo round(3.6);         // 4
echo round(3.60);      // 4
echo round(1.955832);  // 1.96
echo round(1241757, -3); // 1242000
echo round(5.0452);    // 5.05
echo round(5.0552);    // 5.06
?>

Example #2 mode examples

<?php
echo round(9.50PHP_ROUND_HALF_UP);   // 10
echo round(9.50PHP_ROUND_HALF_DOWN); // 9
echo round(9.50PHP_ROUND_HALF_EVEN); // 10
echo round(9.50PHP_ROUND_HALF_ODD);  // 9

echo round(8.50PHP_ROUND_HALF_UP);   // 9
echo round(8.50PHP_ROUND_HALF_DOWN); // 8
echo round(8.50PHP_ROUND_HALF_EVEN); // 8
echo round(8.50PHP_ROUND_HALF_ODD);  // 9
?>

Changelog

Version Description
5.3.0 The mode parameter was introduced.
5.2.7 The inner workings of round() was changed to conform to the C99 standard.

See Also

add a note add a note

User Contributed Notes 25 notes

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25
takingsides at gmail dot com
5 months 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);
}
?>
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13
twan at ecreation dot nl
14 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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3
djcox99 at googlemail dot com
7 months 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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9
Anonymous
3 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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4
php at silisoftware dot com
12 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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5
feha at vision dot to
3 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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3
martinr at maarja dot net
6 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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1
terry at scribendi dot com
10 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 $6.80 per pint'.
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1
craft at ckdevelop dot org
8 months ago
function mround($val, $f=2, $d=6){
    return sprintf("%".$d.".".$f."f", $val);
}

echo mround(34.89999);  //34.90
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0
esion99 at gmail dot com
1 month 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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0
spectrumcat at gmail dot com
5 months 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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0
christian at deligant dot net
2 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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0
michaeldnelson dot mdn at gmail dot com
4 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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0
ianring (at) golden.net
11 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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0
tichoux at charlevoix dot net
11 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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-1
dastra
2 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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-2
tom at crysis-online dot com
7 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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-2
hugues at zonereseau dot com
4 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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-2
Anonymous
4 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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-3
maxteiber at gmail dot com
7 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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-1
Prasad
1 month ago
What should round(-0.25) return?
// 0
or
// -0

Shouldn't it be 0?
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-4
omnibus at omnibus dot edu dot pl
3 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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-4
lossantis at ig dot com dot br
4 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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-4
Bevan
4 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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-11
Anonymous
1 year ago
Note that the returned string does not always include as many decimal digits as required by the precision argument.
It is because the least significant decimal digit(s) is (are) not reported if it is (they are) 0.
So:
<?php
round
(1.105,2); // returns 1.11
?>
but:
<?php
round
(1.104,2); // returns 1.1 instead of 1.10
?>
More:
<?php
round
(1.004,2); // returns 1 (even the decimal point is not reported)
?>
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