(1 RM) lift for weight training exercises. You will need to record your working weight and the number of repetitions completed. To calculate your predicted 1 RM, simply divide your working weight by the appropriate decimal.
NOTE: The following chart will estimate a 1RM for up to 20 completed repetitions.
EXAMPLE: Maximum of 5 reps with 280 pounds
(280 divided by .857 = 325 predicted max.)
REPS DECIMAL
2 .955
3 .917
4 .885
5 .857
6 .832
7 .809
8 .788
9 .769
10 .752
11 .736
12 .721
13 .719
14 .710
15 .704
16 .700
17 .697
18 .694
19 .692
20 .690
NOTE: THIS FORMULA WILL GIVE YOU A CLOSE ESTIMATE ON WHAT YOUR 1RM IS, NOT NECESSARILY A TRUE MAX. REMEMBER THAT THE ONLY WAY TO TRULY KNOW WHAT YOUR 1RM IS, IS TO MAXOUT FOR 1 REP.