What is the 1RM (One Rep Max)?
The 1RM, or One Rep Max, is the heaviest weight you can lift for a single rep on a given exercise. Basically, your personal record on one rep. Athletes and coaches use it as the reference point for programming training.
Knowing your 1RM means you can work with the right load percentages, track your progress, and structure your training cycles.
Why is knowing your 1RM important?
In practice, your 1RM helps you:
- Customize training loads according to your goals (strength, hypertrophy, endurance)
- Objectively measure your progress over time
- Program effective periodized training cycles
- Compare your performance across different exercises and with other athletes
How to estimate your 1RM safely?
Testing your 1RM directly by lifting a maximum load can be dangerous, especially for beginners. That's why estimation formulas exist: they allow you to calculate your theoretical 1RM from a submaximal set (for example, 5 reps at 80 kg).
1RM Calculation Formulas
Two formulas dominate in strength training:
Epley Formula
1RM = Charge × (1 + Répétitions / 30)Developed by Boyd Epley, this formula is particularly accurate for sets of 10 reps or less. It's widely used in gyms and by strength coaches.
Brzycki Formula
1RM = Charge × 36 / (37 - Répétitions)Created by Matt Brzycki, this formula is known for its accuracy on short sets (1 to 6 reps). It tends to give slightly more conservative results than Epley.
The RPE Option: Refine Your Estimate
RPE (Rate of Perceived Exertion) measures how hard a set felt on a 1-10 scale. RPE 10 = muscular failure, RPE 8 = you had 2 reps left in the tank. If you didn't go to failure, RPE lets you correct the estimate.
Common Mistakes to Avoid
Here are the most common mistakes when estimating or testing the 1RM:
- Using too many reps: Formulas are less accurate beyond 10 reps. Prefer sets of 3-6 reps for better estimates.
- Neglecting warm-up: Insufficient warm-up skews results and increases injury risk.
- Poor technique: Incorrect execution overestimates your true 1RM and can cause injuries.
- Ignoring fatigue: Test your 1RM at the start of a session, after sufficient rest, for reliable results.
- Not accounting for RPE: If you didn't go to failure, your estimated 1RM will be underestimated without RPE correction.
How to use 1RM percentages for training?
Once you know your 1RM, you can program your training based on your goals. Here are the commonly used intensity zones:
Concrete Examples by Exercise
Bench Press
For someone lifting 80 kg for 5 reps, the estimated 1RM would be about 93 kg (Epley formula). For a hypertrophy program at 75%, they would work with about 70 kg for 8-10 reps.
Squat
An athlete doing 100 kg for 6 reps would have an estimated 1RM of about 120 kg. To develop strength at 85%, they would use about 102 kg for 4-6 reps.
Deadlift
With 120 kg for 4 reps, the estimated 1RM would be about 136 kg. For technique work at 70%, the athlete would use about 95 kg with a focus on form.