I don't figure honey into my recipe. I generally add 1 tsp ppo and blend it with a bit of warm water. I then add mine to my oils before the lye/water mixture but many add it at trace.
I discount my water by the amount of the honey. Otherwise, I find the soaps are a little too soft for my liking. And that's with an initial water discount of 4-6%.
Honey is about 80% water, give or take a bit. Soapcalc doesn't list it, because it doesn't have anything in it to saponify.
If using just a bit, you can just include it as an additive. If using a fair amount, include it in the water phase part of your recipe like you would any other watery liquid (milk, beer, etc.)
I make a honey and goats milk bar so frankly to this one i add very little water since i use a lot of honey (1/2 cup) and 1/2 cup goats milk. This is for a 2lb loaf bar.
It's recommended to weigh ingredients for soap making since it is more accurate than using volume amounts. Going just slightly over the line or being under the line can make quite a difference in the amount being used. Although, it's probably not an issue with the honey and goat milk like it would be for oils.