I have a recipe that calls for 15 1/2 oz. , I know 16 oz is 2 cups. what the heck is 15 1/2?

get a good set of kitchen scales

That would be 1 cup and 7.5 ounces. Is the 15 1/2 oz for a canned item? If so, the can may be a 15 1/2 oz size.

Just use the whole 16 oz. I have no clue why recipes call for 15 - 16 oz. cans. A little extra beans or something won't hurt.

Just short of 16 oz. Take 16 oz, remove a half oz, although in that quantity it might not matter unless you're baking.

Sounds like it was originally converted from metric.

Go ahead and use the whole 16 oz. The recipe will still work fine.

15 ounces plus 1/2 an ounce too...Just shy of 16 oz.

15 1/2 oz is a typical size can for stuff like tomatoes, beans, canned veggies. I could not hazard a guess as to why.

it is 1/32 removed from 2 cups. Or 1/2 ounce. For most cooking, two cups would work well.

Two cups minus 1 1/2 tablespoons. Three tablespoons make one ounce, so if you need to remove 1/2 ounce, measure your 2 cups and remove the 1 1/2 tablespoons.

Live life dangerously, cheat death, and put 16 ounces in the recipe!!!!! Seriously tho' maybe it's based on a metric measurement perhaps?

depending on the ingredient, i usually use 16 oz so i don't have to figure out how much i am supposed to use.