TL;DR: The official length of halftime in association football (yes, this means soccer) is 15 minutes.
American sports fans are notorious for considering soccer the most boring of the major sports, despite the fact that it is in reality the only sport (major or not) that has literally nonstop action throughout the entire game. Ok, maybe sometimes little European boys more beautiful than your girlfriend roll around screaming and everyone stops, but at least the clock keeps running. I think we can all agree that there would be a lot less stress put on relationships if the NFL had a consistently running clock. Yes, it would also probably ruin the sport. Football or your marriage. Your choice.
So, after stoppage time (another borderline anti-American recipient of unending consternation) comes the only real stoppage of the game: halftime. And halftime can be weird. In fact, most sports fans couldn’t tell you the official length of halftime of their favorite sport– but that’s not completely their fault. While the NFL has the most undependable halftime lengths (I’m still convinced the roughly 45 minute halftime of Super Bowl LI sapped the Falcons’ momentum and precipitated the unlikely comeback), there is a lot of variation generally speaking. Hotter weather can lead to slightly more lenient referees in terms of letting the boys rest, but every sport does have an official standard of its games halftime length.