I've only had 1 digital scale that came close to getting my bf% correct. I wish I could remember the model number/brand.
I've bought 6 different brands now and I always get a reading of over 25%. I'm well hydrated, I enter all the correct info, and it still screws up. The calipers tell me I'm around 12%. I know what 10%-14% looks and I'm in that range. So in my experience the calipers are more accurate then the majority of scales.
That 1 scale that worked for me had a setting to indicate if you were sedentary, mildly active, or athletic. Maybe that made the difference because I had it on the athletic setting
If your going to buy a digital bf scale, save you receipt, and return it if it's garbage.
These guys came to a fitness fair at my work. They had a machine that I held two things in my hand. It looked pretty expensive but also seemed to be accurate.