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Misc. Functions	Last updated: Mon, 26 Oct 2026

usleep

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

usleep — Delay execution in microseconds

Description

function usleep(int $microseconds): void

Delays program execution for the given number of microseconds.

Parameters

microseconds: Halt time in microseconds. A microsecond is one millionth of a second.

Note:
Values larger than 1000000 (i.e. sleeping for more than a second) may not be supported by the operating system. Use sleep() instead.

Note:
The sleep may be lengthened slightly (i.e. may be longer than microseconds) by any system activity or by the time spent processing the call or by the granularity of system timers.

Return Values

No value is returned.

Examples

Example #1 usleep() example

<?php

// Current time
echo (new DateTime('now'))->format('H:i:s.v'), "\n";

// wait for 2 milliseconds
usleep(2000);

// back!
echo (new DateTime('now'))->format('H:i:s.v'), "\n";

// wait for 30 milliseconds
usleep(30000);

// back again!
echo (new DateTime('now'))->format('H:i:s.v'), "\n";

?>

The above example will output:

11:13:28.005
11:13:28.007
11:13:28.037

See Also

sleep() - Delay execution
time_nanosleep() - Delay for a number of seconds and nanoseconds
time_sleep_until() - Make the script sleep until the specified time
set_time_limit() - Limits the maximum execution time

unpack	Changelog

Misc. Functions	Last updated: Mon, 26 Oct 2026