Quick answer: 100 kg lifted for 5 reps gives an estimated 1RM of 116.7 kg by Epley (100 × (1 + 5 ÷ 30)), 112.5 kg by Brzycki and 117.5 kg by Lombardi.
How it's calculated
Epley: 1RM = weight × (1 + reps ÷ 30). Brzycki: 1RM = weight × 36 ÷ (37 − reps). Lombardi: 1RM = weight × reps^0.10. A single rep is already your 1RM, so all three return the weight itself.
The formulas agree closely for 2 to 6 reps and drift apart as reps rise; above about 10 reps the estimate is much less reliable. Use a set taken close to failure with good form.
The %1RM table follows the usual strength-training guide: about 85% for 6 reps, 75% for 10. Real numbers vary by lift, training history and fatigue, and the estimate cannot tell you whether a true maximal attempt is safe for you on the day.
Worked examples
- 100 kg × 5 reps (Epley): 100 × (1 + 5 ÷ 30) = 116.7 kg
- 100 kg × 5 reps (Brzycki): 100 × 36 ÷ 32 = 112.5 kg
- 225 lb × 5 reps (Epley): 225 × (1 + 5 ÷ 30) = 262.5 lb
Percentage of 1RM and typical reps
Approximate reps most trained lifters can complete at each load.
| % of 1RM | Reps |
|---|---|
| 100% | 1 |
| 95% | 2 |
| 93% | 3 |
| 90% | 4 |
| 87% | 5 |
| 85% | 6 |
| 83% | 7 |
| 80% | 8 |
| 77% | 9 |
| 75% | 10 |
| 70% | 11 |
| 67% | 12 |
| 65% | 15 |
Frequently asked questions
Which 1RM formula is most accurate?
None is best for everyone. Epley and Brzycki give near-identical results around 5 reps; Brzycki reads lower at high reps. Pick one and use it consistently to track progress.
How many reps should I use?
Between 3 and 6 reps taken close to failure gives the most dependable estimate. Above 10 reps, errors grow.
Can I use this for any exercise?
The formulas were developed mostly for the bench press, squat and deadlift. They work less well for small or machine exercises.
How do I use my 1RM in training?
Training loads are set as a percentage of it. For example, 70–85% of 1RM is a common range for building muscle and strength, so a 100 kg 1RM means 70 to 85 kg.
Is it safer to estimate than to test a true 1RM?
Usually, yes, especially for beginners. A set of about 5 reps carries less risk than a maximum lift. If you do test, warm up well and use a spotter.
How often should I recalculate?
Every 4 to 8 weeks works for most training plans, or whenever your working weights have clearly gone up.