How much weight did you have to lose to go down a size?

I dropped a pant size about every 10 lbs.

I would imagine that starting weight and body type would play a role. For example, my sister and I weighed the same when I was at my highest weight.. but she wore a smaller pant size because I carry weight more in my hips. It's harder for her to drop pant sizes than me, but she tends to wear smaller pant sizes when we're the same weight.