Hi mrsD, here is a link to the product label:

http://www.iherb.com/Now-Foods-Magne...2&sr=null&ic=2

One 400 mg serving is the sum of three magnesium citrate softgels, so each softgel is about 133 mgs each. According to my ruler, one softgel is exactly one inch in length. I suppose than means there is probably much less than 133mg of elemental magnesium in each softgel.