ONE REP MAX
(1RM)
CALCULATOR
Estimate your one rep maximum using proven formulas. Get training percentages for strength, hypertrophy, and endurance programming.
// ENTER YOUR LIFT DATA
The weight you lifted for the given reps
Number of reps completed with good form
// YOUR ESTIMATED 1RM
ESTIMATED ONE REP MAX
158 LBS
Using Epley formula
TRAINING PERCENTAGES
// TRAINING_ZONES
REP RANGES BY GOAL
STRENGTH
Maximal force production, neural adaptations, peak strength development
HYPERTROPHY
MUSCLE GROWTHOptimal mechanical tension and metabolic stress for muscle growth
ENDURANCE
Muscular endurance, capillary density, work capacity
// 1RM_TRAINING_GUIDE
UNDERSTANDING ONE REP MAX
Your one rep max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It serves as the foundation for percentage-based training programs and helps you track strength progress over time.
WHEN TO TEST YOUR ACTUAL 1RM
While calculators provide useful estimates, testing your actual 1RM can be valuable for competitive powerlifters or when precise programming is needed. However, true 1RM testing carries injury risk and should be approached carefully.
- Only test when fully recovered and warmed up
- Use a spotter or safety equipment
- Test no more than every 8-12 weeks
- Avoid testing during fat loss phases when strength may be reduced
- For most trainees, estimates from 3-5 rep maxes are sufficient
FORMULA COMPARISON
| FORMULA | CALCULATION | NOTES |
|---|---|---|
| Epley | weight x (1 + reps/30) | Most widely used, slightly aggressive |
| Brzycki | weight x 36/(37 - reps) | More conservative, good for higher reps |
| Lombardi | weight x reps^0.10 | Simple exponential formula |
ACCURACY CONSIDERATIONS
All 1RM formulas become less accurate as rep counts increase. For best results:
- Use sets of 1-5 reps for most accurate estimates
- Higher rep sets (8-12) may overestimate your true 1RM
- Individual variation in muscle fiber type affects accuracy
- Exercise selection matters: compounds are more reliable than isolation
PRO TIP
Use your estimated 1RM as a starting point, but adjust based on how you actually perform. If you can easily complete more reps than expected at a given percentage, your working 1RM is likely higher than calculated.
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Disclaimer: These are estimates based on mathematical formulas. Your actual one rep max may vary based on training experience, fatigue, nutrition, and other factors. Always use proper form and safety equipment when training with heavy weights. Consult a qualified coach or trainer if new to strength training.