Master PHP’s microtime(): Precise Timing, Float vs String, and Real‑World Uses

microtime() function basic concept

microtime()

is a PHP function that returns the current Unix timestamp with microseconds, as a string or float.

Syntax and parameters

The function has a single optional boolean parameter $get_as_float. If true, it returns a float; otherwise a string. Default false.

microtime(bool $get_as_float = false): string|float

Parameter description

$get_as_float

: optional, true returns float, false returns string. Default false.

Usage examples

Get seconds and microseconds as string

$time = microtime();
echo $time; // e.g., 0.12345678 123456

The call without arguments returns a string containing seconds and microseconds.

Get current time as float

$time = microtime(true);
echo $time; // e.g., 1580858978.123456

Passing true returns a float representing seconds since the Unix epoch with microseconds.

Application scenarios

Measuring code execution time

$start = microtime(true);
// some code
$end = microtime(true);
$execution_time = $end - $start;
echo "Execution time: {$execution_time} seconds";

Generating unique identifiers

$timestamp = microtime(true);
$unique_id = md5($timestamp);
echo "Unique ID: {$unique_id}";

Conclusion

This article detailed the PHP microtime() function, covering its concept, syntax, parameters, examples, and common use cases such as performance timing and unique ID generation, helping developers handle time‑related tasks more accurately.