I eat coffee grounds.
I have size 000 capsules (just think of the size of the largest supplement capsules you may have seen), a capsule maker, and some Death Wish (which they tout as premium Ruousto, with "twice the caffeine" (that's their marketing line)) coffee, ground to regular drip coffee maker standards (as delivered by the company, to me).
I tamp the ground coffee into those capsules; it's pretty densely compacted. Naturally, I get a bit more caffeine per quantity than as brewed (any method) or as would come from Arabica, but, how many milligrams per capsule, roughly? Anyone able to venture a guess?