Thanks. I think I finally figured it out. One thing I did read is that ALL the labels for Mg are required to tell you the amount of elemental Mg you're getting, but that you may have to "figure it out." My brand is just that kind.

I finally figured out that the Mg Glycinate provides 400 mg Mg in 4 tablets and the Mg Citrate provides 400 mg in 2 tablets.

I liked the fact that the glycinate had a little bit of Ca with it, which I understand is good. But I also would prefer to take 2 a day, like the citrate, instead of 4.

At least I know now I was getting 100mg of Mg a day, so yesterday I added another tablet and will work up to 400 mg from there, as my stomach tolerates it.