PHP Date Conversion: Benchmarking UNIX Timestamp Methods

If I’m given the year, month, day, hour, minute, and second as integers, there are several ways in PHP to convert them into a UNIX timestamp:

// 1. gmmktime() (UTC) → timestamp
$ts1 = (int) gmmktime($hour,$minute,$second,$month,$day,$year);

// 2. mktime() → timestamp
$ts2 = (int) mktime($hour,$minute,$second,$month,$day,$year);

// 3. DateTime → timestamp
$ts3 = (new DateTime("$year-$month-$day $hour:$minute:$second"))->getTimestamp();

// 4. DateTimeImmutable → timestamp
$ts4 = (new DateTimeImmutable("$year-$month-$day $hour:$minute:$second"))->getTimestamp();

// 5. strtotime() → timestamp
$ts5 = (int) strtotime("$year-$month-$day $hour:$minute:$second");

// 6. date_create() → timestamp
$ts6 = date_timestamp_get(date_create("$year-$month-$day $hour:$minute:$second"));

// 7. IntlCalendar → timestamp
$ts7 = (int)(IntlCalendar::createInstance()->set($year,$month-1,$day,$hour,$minute,$second)->getTime()/1000);

I ran a benchmark to compare their performance. The table below shows the average time per execution after running each function 50,000 times.

Methods labeled 1B, 2B, … 7B include a timezone switch before the conversion and then revert to the original timezone afterwards.

Note that the average time is measured in nanoseconds, so all of these methods are actually quite fast unless executed a large number of times.