How to convert week number and year into unix timestamp?

I assume you are using ISO 8601 week numbers, and want the first day of a ISO 8601 week so that e.g. Week 1 of 2011 returns January 3 2011.

strtotime can do this out of the box using the {YYYY}W{WW} format:

echo date("Y-m-d", strtotime("2011W01")); // 2011-01-03

Note that the week number needs to be two digits.

Shamefully, DateTime::createFromFormat, the fancy new PHP 5 way of dealing with dates, seems unable to parse this kind of information – it doesn’t have a “week” placeholder.

Leave a Comment