I just had both of them done. I think the calipers was more accurate. It said 20% and the scale (it was a little thing almost like a gun put on my bicep) said 18%. I don't think I'm that low. I have read only underwater weighing is very accurate. The calipers can be accurate if the person using them has the proper training and technique. I don't know a lot about these scale and guns - don't they measure it using electricity? I operated one for several hours at a health fair and measured a lot of people that way. There were only two people that I thought the reading was way, way off base. (one too low, one too high). Most of them were in the ballpark. Very overweight people were in the upper 30 - 40 % (kind of shocking, huh?) and the young, skinny ones were in the teens, some low teens. So that's my two cents. I have to say this - the men were as uncomfortable as the women about telling me their weight. They are as vain as we are.