The best way I've found to measure my penis has always been his length by placing the tape measure against my pubic bone on top of dick, stretch tape down top of shaft, over corona of head, then down to head's slit (about 1/2 of its length if its an extra long slit). To me this gives an accurate measurement. Oh, make sure he's as stiff and enlarged as he can get! This might require taking the longest of three or four tries. As for girth just wrap tape measure around the sucker at his thickest point, even if its his head's corona. I hope this helps. Have fun!