From several sources on the net I destilled this method on how to use the Tanita scale to accurately predict BF%:
Have your BF% visually estimated by an expert, like many on this forum are (eventually a caliper measurement by an experienced person).
Put your Tanita in Athlet-mode, change a) your age with units of 10 year and b) your height with units of 10 cm, up or down until you get the right BF%.
Example: how older how more your beerbelly is taken into account (internal fat) and how taller you are how lower the BF% will be (density of LBM).
This way you calibrate the internal table with your own body composition.
After this the BF% should be quite accurate.
Remember always to compare the BF-weight instead of the BF%! That will be more constant from day to day.
(use your scale only after drinking enough water (1 liter), before dinner and before workout, don?t drink or eat in the hour (and go to the toilet)before measuring.
(Sorry for bad english..)
We have to make things as simple as possible, but not simpler (A.E.)