Here are the official L.A. Pump instructions on measuring cylinder sizes (table below).

  1. Wrap a piece of string around the thickest part of your penis. This might be around the head of the penis, or at the base. A tape measure is not recommended.
  2. Using a pen, mark where the string crosses itself.
  3. Lay the piece of string next to a ruler. This measurement will be the circumference of your penis.
  4. In the table below, find the corresponding Penis Outside (Circumference) measurement and the column to the right is the Cylinder tube inside diameter that you can buy inside the shop.
What size cylinder should I get?

Penis Outside
(Circumference)
Cylinder Order Size
(Tube Inside Diameter)
4 3/4″ 1 1/2″
5 1/2″ 1 3/4″
6 1/4″ 2″
7″ 2 1/4″
7 7/8″ 2 1/2″
8 5/8″ 2 3/4″
9 3/4″ 3″
10 1/4″ 3 1/4″
11 3/4″ 3 3/4″
13 3/8″ 4″
14 1/4″ 4 1/2″
15 3/4″ 5″
17 1/4″ 5 1/2″
18 3/4″ 6″
20 1/4″ 6 1/2″
21 3/4″ 7″
24″ 7 3/4”
25 1/4″ 8″