Two well-known polishing methods are used for the inner surface cleaning of superconducting TESLA-shape cavities: electro-polishing (EP) or buffered chemical polishing (BCP). The amount of removed material is relatively small and varies from 5 till 140 μm. The cavity is closed after polishing to prevent scratches or dust appearing on its inner surface. The estimation of the removed material amount is possible by different criteria, for example by comparison of weight before and after cleaning, or by the time - cleaning procedure duration. Both calculations could give us only approximate average value of the removed material amount.We describe the method for estimation of small geometry deviation basing on RF frequency measurements, which allows calculation of the different influence of surface treatment on the iris and equator areas
