Calcium carbonate is the least expensive and to be absorbed needs to be taken with meals. The body only absorbs so much calcium at once so in the case of a calcium chew which contains 650mg, I would break it in half and take at different times. I just used this as an example. Capsules, tablets all good. Calcium carbonate is terribly constipating so if that's an issue go to calcium citrate which has the added benefit of being absorbed without having to take with food.