It probably doesn’t have much to do with pounds, since weight could be gained with either fat or muscle.

Approximately 15. And as @jellyfish3232 says, there is a muscle component involved. If you’re working out, you may lose inches before you lose pounds.

@tedibear is right. 15 lbs. is a clothes size.

I think that it also depends on the size. When you are talking about going from a size 2 to a size 4, it might be less than 15 pounds. When you are going from a size 20 to a 22 it might be 15 or more pounds.
I find when I’m smaller, every pound seems to make more of a difference.

When gaining weight I usually stay in denial 2 or3 sizes to long.

Tricky. Muscle weighs more than fat. And you got to figure in height. Then you got to figure that people lose weight at different distributions. A few pounds on your waist is totally different than a few pounds from your thighs. Not to mention that each brand varies in size too.

Sorry! I’m not too helpful!

The best measurement is a measuring tape. Each two inches of bust and waist equals another clothes size for most people. If you’re under 5’6” then 15lbs can mean 3 sizes!

You also have to take into account the clothing line. My mom and sister always complain that they are not the same from one store to the other, and sometimes even from one line of clothing to another in the same store.