1st TRimester ending date?😐

Winnie • Hey y`all:)
Okay, so some are saying the 1st trimester ends at 12 weeks (which I agree with) , but others are saying the 1st trimester doesn't end til 20 wks!! Lol which one is it?? I really don't think it's logical to say your first trimester lasts for HALF your pregnancy lol. If that were the case you'd only have 2 trimesters your entire pregnancy 😑