Question 1

How accurate is a 1 rep max calculator?

Accepted Answer

Very accurate inside about five reps, and progressively less accurate beyond ten. A set of three to five reps taken close to failure gives the most reliable estimate.

Question 2

Which formula does this use?

Accepted Answer

The Epley formula: one-rep max = weight x (1 + reps / 30). It is the most widely used estimate and matches tested maxes closely in the one-to-ten rep range.

Question 3

What percentage should I train at?

Accepted Answer

Strength work usually sits at 80–90% for 3–5 reps, size work at 65–80% for 6–12 reps, and technique or speed work at 50–65%. The chart below converts your estimate for you.

Question 4

Should I test a true one-rep max?

Accepted Answer

Rarely. A calculated max from a hard set of three to five carries almost no injury risk and is enough to program from. Save real max attempts for a meet or a planned peak.

% of max	Weight	Typical reps	Use it for
95%	249.5 lb	2–3 reps	Peaking, top singles
90%	236.5 lb	3–4 reps	Heavy strength work
85%	223 lb	5–6 reps	Main strength sets
80%	210 lb	7–8 reps	Strength and size overlap
75%	197 lb	9–10 reps	Hypertrophy
70%	184 lb	11–12 reps	Hypertrophy, volume days
65%	170.5 lb	13–15 reps	Technique and conditioning
50%	131.5 lb	Warm-up	Bar speed and practice

1 rep max calculator

Your training weights

How to use your estimate

Common questions