One Rep Max Calculator
Estimate your 1RM from weight and reps performed.
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Epley Formula
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Brzycki Formula
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Percentage Table (Epley)
| % | Weight | Est. Reps |
|---|
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Frequently Asked Questions
What is the difference between the Epley and Brzycki formulas? +
Epley uses the formula weight x (1 + reps/30), while Brzycki uses weight x 36/(37 - reps). They produce very similar results at lower rep ranges (1-6) but diverge slightly at higher reps. Brzycki tends to give slightly lower estimates above 10 reps.
How many reps should I use for the most accurate estimate? +
Sets of 3-6 reps give the most accurate 1RM predictions. Above 10 reps, the formulas become less reliable because muscular endurance starts to play a bigger role than maximum strength.
How do I use the percentage table for programming? +
Common rep ranges by percentage: 90-100% for 1-3 reps (strength), 75-85% for 5-8 reps (hypertrophy), and 60-70% for 12-15 reps (endurance). Use the table to find the weight for your target rep range.
Should I actually attempt a true one rep max? +
True 1RM testing carries injury risk, especially without a spotter. Estimating from a 3-5 rep set is safer and nearly as accurate. If you do test, warm up thoroughly and have an experienced spotter present.
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