I have to agree with clynn11, the easiest way to tell is the space between the anus and genitals, in females they are close together, in males there is a much bigger space between them
You've surely got boys, but the calico would be a girl!
The tabby is a boy, for sure. But I kind of think I see a slit on the black & white. . .but yeah, since you have a known female and a known male now, compare the other 2 to them and see who they match!
I thought the black one may have had a slit as well but then looked further down and was maybe thinking it was the beginning of his testes? Not sure, that one did have me a bit confused. But yes, like Willowy said use the tabby as a boy model and calico as a girl model and you should be able to sort them all out
The picture isn't really good enough to say. . .it's hard to get a good picture on a darker kitty :/. Maybe try to get a pic in better light like the tabby's picture?