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Sports • One-Rep Max (1RM) & Powerlifting Suite

One-Rep Max (1RM) & Powerlifting Suite

Estimate your maximal 1RM lift across Brzycki, Epley, and Wathan equations with percentage training loads and Wilks score.

Biomechanics & Strength Science

One-Rep Max (1RM), Wilks & Powerlifting Suite

Estimated 1-Rep Max (1RM)
116 kg
Epley: 116.7 kg | Brzycki: 112.5 kg | Wathan: 116.6 kg
Training Load Percentages (% of 1RM):
100% (1 Rep Max)
116 kg
95% (2 Reps)
111 kg
90% (3 - 4 Reps)
105 kg
85% (5 - 6 Reps)
99 kg
80% (7 - 8 Reps)
93 kg
75% (9 - 10 Reps)
87 kg
70% (11 - 12 Reps)
82 kg
65% (14 - 15 Reps)
76 kg
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Calculation Guide & Reference

One-Rep Max (1RM) Strength Mathematics

One-rep max calculator estimates your 1RM strength from a submaximal lift using the Epley, Brzycki, Wathan, Lombardi, and Mayhew formulas.

Standardized Mathematical Formula
Epley: 1RM = W × (1 + Reps/30)

Since lifting to true 1RM failure is risky, strength coaches estimate it from a lighter, higher-rep set. The Epley formula is one of several regression equations (alongside Brzycki, Wathan, Lombardi, and Mayhew) built from lifting-performance data; this tool averages all five for a more reliable estimate.

Variables:
W:Weight lifted
Reps:Repetitions completed with that weight
How It Works (Step-by-Step)
  • 1Enter the weight lifted and the number of repetitions completed.
  • 2View your estimated 1RM (averaged across five formulas) and a percentage-based training load table.
Real-World Numerical Example
100 kg for 5 Reps

A lifter completes 5 reps at 100 kg on the bench press.

•Epley: 100 × (1 + 5/30) = 116.7 kg.
•Brzycki: 100 × (36 / (37−5)) = 112.5 kg.
•Wathan, Lombardi, and Mayhew give 116.6, 117.5, and 119.0 kg respectively.
•Average of all five formulas: 116.4 kg, rounded to 116 kg.
Result: The estimated one-rep max is approximately 116 kg.
Calculation Best Practices & Tips
Use the Brzycki formula (1RM = Weight / (1.0278 - 0.0278 * Reps)) for sub-maximal sets between 2 and 10 repetitions.
Pace consistency during the first half of a marathon is the single greatest predictor of achieving personal record finish times.

Frequently Asked Questions (FAQ)

The most common method is the Epley formula: 1RM = Weight × (1 + Reps ÷ 30). Averaging several formulas (Epley, Brzycki, Wathan, Lombardi, Mayhew) generally gives a more reliable estimate than any single one.

Multiply your estimated 1RM by 0.80. For a 116 kg 1RM, that's 92.8 kg — a load typically used for 7-8 rep strength-hypertrophy sets.

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