1 Rep Max Calculator (1RM)
Calculate your estimated 1 Rep Max across five validated scientific strength formulas. Evaluate working set percentages and generate a customized 5-stage barbell warm-up protocol.
🧮 Enter Your Lift Details
Calculated across 5 validated strength formulas based on 225 lbs × 5 reps.
📊 5 Formula Calculation Comparison
Epley Formula
W × (1 + R/30). Most widely used for 1–10 rep ranges.
Brzycki Formula
W × 36/(37−R). Accurate for 1–8 heavy reps.
Lander Formula
100×W / (101.3 − 2.67123×R). Conservative high-rep formula.
Lombardi Formula
W × R^0.10. Exponential strength scaling model.
Mayhew Formula
100×W / (52.2 + 41.9×e^−0.055R). High-rep non-linear model.
5-Formula Average
Recommended balanced benchmark target.
📈 Training Load Percentage Matrix
| Percentage of 1RM | Target Weight (lbs) | Estimated Rep Limit | Training Zone Purpose |
|---|---|---|---|
| 100% | 261 lbs | 1 rep | Maximal Strength / Peak |
| 95% | 248 lbs | 10–15 reps | Maximal Strength / Peak |
| 90% | 235 lbs | 3–4 reps | Maximal Strength / Peak |
| 85% | 222 lbs | 10–15 reps | Hypertrophy / Heavy Strength |
| 80% | 209 lbs | 7–8 reps | Hypertrophy / Heavy Strength |
| 75% | 196 lbs | 10–15 reps | Endurance / Volume |
| 70% | 183 lbs | 10–15 reps | Endurance / Volume |
| 65% | 170 lbs | 10–15 reps | Endurance / Volume |
| 60% | 157 lbs | 10–15 reps | Endurance / Volume |
| 50% | 131 lbs | 10–15 reps | Endurance / Volume |
🔥 5-Stage Barbell Warm-Up Protocol
| Warm-Up Set | % of 1RM | Load (lbs) | Reps | Rest Duration |
|---|---|---|---|---|
| Set 1 | 40% | 104 lbs | 10 reps | 60 sec |
| Set 2 | 50% | 131 lbs | 8 reps | 60 sec |
| Set 3 | 60% | 157 lbs | 5 reps | 90–120 sec |
| Set 4 | 75% | 196 lbs | 3 reps | 90–120 sec |
| Set 5 | 85% | 222 lbs | 1 reps | 90–120 sec |
What is a 1 Rep Max (1RM)?
Your 1 Rep Max (1RM) is the maximum amount of weight you can lift for a single, fully-completed repetition with proper execution form. It serves as the primary benchmark metric in resistance training, powerlifting, and strength conditioning to program working intensities, percentage-based periodization blocks, and warm-up loads.
How Are 1RM Estimations Calculated?
Directly testing your true 1RM with heavy maximal loads carries an elevated risk of muscular fatigue or injury. Submaximal rep estimation formulas allow lifters to predict their 1RM using lighter, safer working weights (such as a 3-rep or 5-rep set).
- Epley Formula: Ideal for standard 1–10 rep working sets (1RM = Weight × (1 + Reps / 30)).
- Brzycki Formula: Highly accurate for heavy lower-rep sets (1RM = Weight × 36 / (37 - Reps)).
- Lander Formula: Provides conservative estimates for higher rep sets (1RM = 100 × Weight / (101.3 - 2.67123 × Reps)).
- Lombardi Formula: Exponential power curve model (1RM = Weight × Reps^0.10).
- Mayhew Formula: Non-linear regression curve designed for high-intensity multi-rep sets (1RM = 100 × Weight / (52.2 + 41.9 × e^(-0.055 × Reps))).