EPC — earnings per click — is one of the clearest ways to compare how well different affiliate links or programs actually perform for your traffic.
EPC is simply total earnings divided by total clicks — the average amount a single click on your affiliate link is worth. It's most useful for comparing performance across different programs, pages, or placements, since it normalizes for traffic volume: a page sending fewer, better-matched clicks can easily have a higher EPC than one sending far more clicks that don't convert as well.
Once you know a program's typical EPC (many programs publish this in their affiliate dashboard), you can flip the calculation around — the second tab here does exactly that, projecting expected earnings from a given amount of traffic.
What's considered a "good" EPC? It varies enormously by niche and program — there's no universal benchmark. The more useful comparison is your own EPC across different pages or traffic sources, to see what's actually working.
Does a higher EPC always mean a better program? Not necessarily on its own — a program with a higher EPC but a much lower approval rate or longer payment terms might still be a worse overall fit. EPC is one input, not the whole decision.