Hello Chris Thank you for the reply. The TIN is made from x y z points in (Longitude , Latitude, Elevation in meters) e.g. (-106.5 , 51.6, 555) At first I used the (Geographic (Latitude/ Longitude)) projection but the distance calculated between two points were not correct. So I reproject the maps to UTM. Projection : UTM Zone: 13(108w-102w)Northern hemisphere Datum: NAD83 Planar Units: METERS I checked the distance between two points that I know the distance in reality (51 4' 45"/106 37' 10" and 51 6' 17"/106 39' 0.5") . The distance should be around 3500 meters which is correct in UTM projection . (In the Geographic projection it was 0.0394 m). So I have everything in meters and when I am using the ruler I have correct values for distance. The segment Length is also correct but the layer width is not. I also checked the calculated storage capacity which is not correct and consequently the layer width. Amir