The Tanita scales are set up for NON-bodybuilders. They get less accurate. They have an "athlete" model.

They can measure bf%, within a error range, but calipers have a couple % error range as well.

your weight, hydration, etc fluctate throughout the day..... You should use the scale as a guage of progress. Be sure to way your self at the same time every day. Like every Thursday AM if training, eating, drinking water consistently. Or every Thursday AM & PM, and average the two readings.