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1-Rep Max (1RM) Calculator

Daniel Brady | December 18, 2012 in Tools

Simply type in the maximum you can lift for a certain amount of reps and the calculator will predict your 1RM, your 1-Rep Max along with your 3RM, 6RM, 10RM and 12RM.

There are multiple formulas for predicting 1RM, so this calculator could vary slightly with other ones, since the formula used may differ. This calculator uses the Brzycki 1RM Formula ( 1RM = W x (36 / (37 – R)) ).



1RM Waiting…
3RM Waiting…
6RM Waiting…
10RM Waiting…
12RM Waiting…
Weight Lifted
Reps Completed (max 12)


1RM Formulas

Here are some different formulas for calculating 1-Rep Max:

  • Brzycki: 1RM = W x (36 / (37 – R))
  • Wathan: 1RM = (100 x W) / (48.8 + (53.8 x e-0.075 x R))
  • Lander: 1RM = (100 x W) / (101.3 – 2.67123 x R)
  • Epley: 1RM = W x (1 + 0.0333 x R)
  • Lombardi: 1RM = W x R0.1
  • Mayhew et al.: 1RM = (100 x W) / (52.2 + (41.9 x e-0.055 x R))
  • O’Conner et al.: 1RM = W x (1 + 0.025 x R)

Daniel has a strong interest in evidence supported fitness training, preparation and supplementation. His goal is to provide clear information that simply works. He's currently 16 kg of muscle above his starting weight (7kg in the past 12 months), and targeting a continued growth rate of 5kg+ per year.
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