NTRP, UTR, WTN: how do the tennis rating systems compare?

Four numbers on four different scales, none of which converts cleanly into the others. NTRP is a banded self-rated and computer-rated US system. UTR is a continuous scale driven by match results. WTN is the ITF's equivalent. A club level is whatever your club says it is. Any mapping between them is an approximation, and anybody presenting one as exact is selling something. How Deuce reads them. What each NTRP level looks like in a match is on the NTRP rating chart.