2021 Sporting Regulations see the maximum time an F1 race can last reduced from four hours to three.
Traditionally, certainly in recent years, F1 races are limited at just over 300 kilometres and last around 90 to 120 minutes.
However, if a race is suspended the clock is stopped until the event resumes.
Following the 2011 Canadian Grand Prix, which lasted 4 hours, 4 minutes and 39 seconds, after the 70-lap race was suspended due to heavy rain, before restarting almost two hours later, new regulations were introduced limiting the length of a race to four hours.
Since that time, the longest race was the 2016 Brazilian Grand Prix which clocked in at 3 hours, 1 minute and 1 second. However, last month's Bahrain Grand Prix lasted 2 hours, 59 minutes and 47 seconds due to the stoppage following Romain Grosjean's crash.
In the 2021 Sporting Regulations, which were published today, Article 5.3.b) now reads "should the race be suspended the length of suspension will be added to this (race) period up to a maximum total race time of three hours".