Depends on some factors, but required and also common is 30/45 minutes, +10% longer flights, before diversion (that fuel not included). Recently experienced a

Depends on some factors, but required and also common is 30/45 minutes, +10% longer flights, before diversion (that fuel not included). Recently experienced a closed airport, needed to divert, and even with chances high that we need to circle again for a while, we only took 1 hour fuel for circling before 2nd divert (and luckily made it after 40 minutes). It was no big jet, but some bigger especially cannot even land with too much fuel.