NTRP ratings are used for adult players or youths playing in an adult USTA competition. The ratings are divided into levels between 1.5 and 7.0. Unlike a Junior NTRP rating, the scale increases in .5 increments.
A player with a 1.5 NTRP rating has had limited experience with stroke development and is still working primarily on getting the ball into play and is not yet ready to compete. By contrast, a 3.0 player is fairly consistent when hitting medium-paced shots but is not comfortable with all strokes and lacks execution when trying for directional control, depth, pace or altering the distance of shots.
At the top end of the rating spectrum, a 6.0 player typically has had intensive training for national tournaments or top-level collegiate competitions and has obtained a national ranking. The 6.5 and 7.0 are world-class players.