Look at the genital area between the kitten’s back legs (anus above, genitals below)
Check the distance between anus and genital opening
Note that males usually have a larger distance between anus and scrotum openings
Note that females usually have a smaller distance between anus and vulva opening
Identify the shape of the opening:
Males typically show a round opening with a noticeable scrotal bulge (more obvious as they get older)
Females typically show a vertical slit-like opening
Use good lighting and a steady hold; keep the kitten calm and supported
If the kitten is very young and markings are unclear, wait until they are older (often easier after about 8–12 weeks)
If unsure, schedule a vet check or ask a shelter/rescue for a confirmation