Turmeric is about 5% curcumins by weight, or it takes about 20 grams of turmeric to get 1 gram of curcumins.
But you can’t go eating it by the spoonful because: 1) that’s nasty; 2) it’s messy and stains everything yellow; and 3) it’s not bioavailable, like, at all.
Fortunately, bioavailability is drastically increased by black pepper &/or dietary fat. For this reason, most curcumin supps contain either piperine or some sort of lipids. I’m not a big fan of piperine because it seems to non-selectively increase the absorption of tons of things – and there are some things we don’t absorb for a reason: they’re toxic… so I’d rather just use a little pepper and take it with some seafood.