Mastering PHP’s strtotime(): Convert Human Dates to UNIX Timestamps

strtotime()

is a powerful and flexible PHP function that converts human‑readable date and time strings into UNIX timestamps.

A UNIX timestamp is an integer representing the number of seconds elapsed since 00:00:00 UTC on 1 January 1970.

Basic Syntax of strtotime()

strtotime(string $time, int $now = time()): int|false

In this signature, $time is the date/time string to be converted, and $now (optional) provides a base timestamp for relative calculations. The function returns a UNIX timestamp or false on failure.

Common Format Examples

Relative dates and times such as "now", "tomorrow", "next week".

strtotime("tomorrow")  // returns the UNIX timestamp for tomorrow

Absolute dates and times.

strtotime("2023-10-31")          // timestamp for the given date
strtotime("2023-10-31 08:30:00") // timestamp for the given date and time

Relative time intervals.

strtotime("+1 day")                     // timestamp for one day later
strtotime("+1 week 2 days 4 hours 30 minutes") // timestamp for the specified interval

Special keywords such as "last day of month" or "first day of next month".

strtotime("last day of month")   // timestamp for the last day of the current month
strtotime("first day of next month") // timestamp for the first day of the next month

Note that strtotime() has limited parsing capabilities; it may not handle uncommon or malformed date formats. Ensure input strings follow supported patterns.

Additionally, strtotime() supports extra parameters like time zone settings or specifying weekdays, which can further enhance its flexibility.

Summary

strtotime()

is a highly useful PHP function for converting readable date strings into UNIX timestamps, enabling easy date arithmetic. However, its parsing is limited, so verify that input formats are standard before using it.