Estimates get less reliable above about 12 reps. Fewer, heavier reps give the most accurate number.
Estimated one-rep max
0
Average of the Epley and Brzycki formulas
Percentage of max, for programming training days
Estimated from a repetition-max formula, not a tested max. It is not medical or coaching advice. Warm up properly and use a spotter or safety bars when you attempt a heavy lift.