Walking/Sandy Terrain Question

Drop_it_Like_Its_Hawt

So I just started, and apologize if this has already been answered somewhere, but I'm trying to log my beach walks in, and wonder if there's any specific way to calculate how many calories you burn walking on dry sand, as opposed to dirt or sidewalk? I know I'm getting exhausted and sweating a lot more walking on the beach than I am on a sidewalk, so I can only assume it's more. I just don't know how MUCH more, you know?