I am trying to figure out the lifting capacity of my hypothetical balloon.

It will be a 300'x75' cylinder. I know there are many variables as to how much weight one foot cubed of hydrogen can lift, but by what I have heard (Correct me if I am wrong), it is somewhere in the ball park of 0.07 lb.

I am using ((pi*radius squared*length)*Lift of 1' cubed hydrogen).

So I figure first, 75 / 2 = 37.5

Next, 37.5 Squared = 1406 (I am rounding)

Then, 1406 x pi = 4,418

Next, 4,418 x 300 = 1,325,359

Lastly, 1,325,359 x 0.07 = 92,775

This leads me to believe the gross lifting weight of the balloon will be around 46 tons.

Is my math correct here? Thank you for viewing!

*Edit* Derp, I just realized that this should have gone under math... Really sorry for that.