It's crucial to select the right-sized penis pump for maximum benefit. If the pump is too big or too small, the vacuum created inside it won't exert the ideal pressure, rendering your workouts less effective and leaving you missing out on potential gains. To make it easier, you can refer to this Bathmate size guide that outlines the minimum and maximum lengths and girths suitable for each pump size.
Measure your erect penis with a ruler pressed lightly onto your pubic bone. You`ll find a ruler is easier than a tape measure.
Record the measurement from the pubic bone right up to the tip of your penis.
See the illustration below.
Measure the circumference of your erect penis around the middle of your shaft
You’ll find a tailors tape measure is easiest, but a piece of string wrapped round and then measured against a ruler after will do.
See the illustration below.