Comparison

High Potency Calcium 1000 +D3 and Oyster Shell Calcium 500 +D Extra Vitamin D Value Size

High Potency Calcium 1000 +D3 (21st Century) lists 2 distinct ingredients and Oyster Shell Calcium 500 +D Extra Vitamin D Value Size (21st Century) 2 (rows of one ingredient counted once); 2 are on both labels. On the site's similarity measure, which compares ingredient lists (1 for the same list, rarer ingredients counting for more; amounts are not part of it), the two formulas score 1.00: the same ingredients, at the amounts in the table below.

Amount per serving (and % of the Daily Value)
IngredientHigh Potency Calcium 1000 +D3Oyster Shell Calcium 500 +D Extra Vitamin D Value Size
Calcium1,000 mg (77%)1,000 mg (77%)
Vitamin D20 mcg (100%)20 mcg (100%)

Amounts are per serving as DSLD gives them: High Potency Calcium 1000 +D3, 1 tablet; Oyster Shell Calcium 500 +D Extra Vitamin D Value Size, 2 tablets. Current labels entered March 2015 and July 2012. Percentages of the Daily Value from 21 CFR 101.9. Source: NIH ODS Dietary Supplement Label Database.

Each product on its own