Gently lift the kitten’s tail
Look at the shape and spacing of the openings
Female kittens usually have a vertical slit close to the anus
Male kittens usually have a round opening farther from the anus
Female kittens often look like an exclamation mark
Male kittens often look like a colon
Check when the kitten is calm and warm
Use good lighting
Compare with a clear reference image if needed
Ask a veterinarian if you are unsure