I'm almost certain that my other 3 are female (buff orpington, and black and red sexlinks ), but my australorp seems to be showing a possibility of being either! I purchased a female with a "5% chance of error"
I've been reading in a lot of these threads specifically about australorps but mine seems to have a couple things different.
1) The birds in the photos people have posted around 6 weeks old, the age mine are, seem less feathered out. This might not actually be the case but i thought it worth mentioning. May turn out not to be am australorp at all for all I know!
2) It seems that they either have no comb at all or are already bright red by 6 weeks. Mine has a larger comb than the other girls and most other australorp it seems but it is NOT red. Barely a touch of pink, really just a fleahy tone. There's a sign of wattles but they aren't really developed.
I know time will tell, but I wanted to get some ideas from other people, some more experienced ones.
Hopefully these photos will show and help.