Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Testing it directly is risky, so most lifters estimate it from a lighter set.
Two Common Formulas
Epley: 1RM = weight × (1 + reps ÷ 30)
Brzycki: 1RM = weight × 36 ÷ (37 − reps)
Worked Example
You bench press 80 kg for 5 reps.
- Epley: 80 × (1 + 5 ÷ 30) = 80 × 1.167 = about 93 kg
- Brzycki: 80 × 36 ÷ 32 = 90 kg
So your estimated 1RM is roughly 90-93 kg.
Training With Percentages of 1RM
Using about 93 kg as the 1RM:
| Percent of 1RM | Weight | Typical use |
|---|---|---|
| 70% | ~65 kg | Muscle building, higher reps |
| 80% | ~75 kg | Strength and size |
| 90% | ~84 kg | Heavy strength work |
Tips for Accurate Estimates
- Use a set of 10 reps or fewer. Estimates get less reliable at higher reps.
- Use strict form, with the same range of motion each time.
- Warm up properly before heavy sets.
- Retest every 4-8 weeks as you progress.
Safety First
Always use a spotter or safety bars for squats and bench press. Never test a true max alone or when tired.
Calculate It Quickly
Enter your weight and reps into a one rep max calculator to see your estimate and percentage table. To fuel your training, check your protein needs and track your progress with a body fat calculator.
FAQ
Which formula is best? Epley and Brzycki give similar results for low reps. Pick one and stay consistent.
Do I need to test my true 1RM? Not usually. Estimated maxes are enough for programming.
Does 1RM apply to all exercises? It works best for big compound lifts like squat, bench press, and deadlift.
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