Dosing differnces

my doctor originally placed me on .5ml (100mg) of testosterone cypionate per week. After getting tired of the shots, I asked to be switched to the gel. He told me to take 4 pumps (40mg) per day. Now doing the math, 40mg x 7 days = 280mg of testosterone per week. Why such a difference in dosing between the cypionate (100mg / wk) and the gel (280mg / wk)? Is there some big difference in how they work? Thanks for the help.

The math doesn't apply here. You cannot compare dosages between different administration routes.

Gel is poorly absorbed by the skin. It's estimated only about 10% passes through, and that's 100% test, unlike testosterone cypionate where the latter term stands for an ester attached to the molecule. That means test cyp isn't 100% test by weight.