Fingers crossed for you walpole
Bitey try a piece of string to measure, start at the head & kind of run the string along with the snake as it slides through your hand then mark the string where the tail ends & measure it. It takes a bit of practise but once you get the hang of it it's so easy to measure them & no stupid computers involved
or just wait for a shed and line it up try not to stretch the skin so u get a more accurate result