Mastering PHP’s fmod(): Calculate Float Remainders with Examples

fmod() function usage

In PHP, fmod() calculates the remainder of two floating‑point numbers. Syntax: float fmod ( float $x , float $y ). $x is the dividend, $y the divisor, and the function returns a float.

Note that fmod() works only with floats; use the % operator for integer remainders.

Example 1

$x = 10.5;
$y = 3.2;
$result = fmod($x, $y);
echo $result; // 1.7

This calculates 10.5 ÷ 3.2 remainder, outputting 1.7.

Example 2

$x = 7.2;
$y = 1.5;
$result = fmod($x, $y);
echo $result; // 0.9

Result is 0.9.

Example 3

$x = 5.5;
$y = 0;
$result = fmod($x, $y);
echo $result; // NAN

If the divisor is zero, fmod() returns NAN.

Example 4

$x = -5.5;
$y = 2.2;
$result = fmod($x, $y);
echo $result; // -1.1

Negative numbers follow specific rules; this example yields -1.1.

Summary

The fmod() function computes the floating‑point remainder of $x divided by $y, returning a float. It cannot be used for integer remainders, returns NAN when $y is zero, and has defined behavior for negative operands.