How to Determine the Sex of Your Tarantula: Rick C West - Birdspiders.com
Sexing | Tarantula Husbandry | TARANTULAS.com
Quote from second website
" It is true that adult females are generally larger (often significantly so) and more heavily built than males"
Dont know if this will help either but this is Tink and "she" was a mature male
this is my hand 100% scale (okay maybe 98% but close enough)
so stick your hand ontop of it and see how big he (Tink) would be in your hand
might give you a nice comparison for your spidey