How To Measure For A Pocket Bra?

[SissySarah]

Up until now I put on either bralett or stretch bra. I like the way they fit, but now I would like to start wearing breast forms.

I see that to purchase a pocket bra I need to know the band size as well as the cup size I'd like. I know I want either a C or D cup. What I don't know is how to measure for the band size.

Thank you.