How come the magnesium glycinate says 800mg but when you look at the like listed thing on the label it says 200?

That's due to FDA regulations. For nutrients with an RDI, you have to list them in the Supplement Facts box very specifically. For magnesium, that means you have to list the elemental magnesium per serving. It's saying there is 200mg ELEMENTAL magnesium per serving. Not all the dose of magnesium glycinate is magnesium. You have the weight of two glycine molecules for every one magnesium. There is 1,600mg of magnesium glycinate per serving in our capsules, but that gives you 200mg elemental magnesium. You also have to never be below label claims for things with an RDI. This means that if you claim 200mg elemental, no capsule can ever come below that number. This means that the FDA wants you to lower your claims for things with RDI a bit on the label, to ensure you are never under that number. Also, the elemental magnesium ranges in % for magnesium glycinate from batch to batch. It's between 12% and 14% most of the time. This means to comply with FDA regulations, you have to use the lower of the range. That would be 12%. However, we always build in a 5% overage. This is where our label claim of 200mg elemental magnesium per serving comes from. You will never get less than 200mg elemental magnesium per serving in our product.