1RM (One Rep Max)
The maximum weight you can lift for a single repetition with proper form.
Updated
Your one-rep max (1RM) is the heaviest weight you can lift once with good technique. It is a measure of maximal strength and is used to calculate training percentages. For example, hypertrophy training often uses 65-85% of 1RM. You can test your 1RM directly (with spotters) or estimate it using rep max calculators based on how many reps you can complete with a submaximal weight.
Work yours out: 1RM calculator
Estimating a 1RM from a heavier set
A one repetition maximum is specific to the exercise and the standard it is lifted to, so a paused bench 1RM and a touch-and-go bench 1RM are different numbers. Most lifters never need to test one directly, because a hard set of three to five reps gives a usable estimate. The Epley formula is 1RM = weight × (1 + reps ÷ 30), so 100kg for 5 reps estimates 100 × 1.167 = 116.7kg. The Brzycki formula, weight × 36 ÷ (37 − reps), gives 112.5kg for the same set. Treat the gap between the two as a reminder that both are estimates.
Testing it directly
If you do test, build up gradually: for an expected 120kg squat, something like 5 reps at 60kg, 3 at 85kg, then singles at roughly 95kg, 105kg and 112.5kg, followed by attempts in 2.5 to 5kg jumps. Rest three to five minutes between the heavy singles and aim to find the number within three to five of them, because each extra attempt adds fatigue. Use safety arms or competent spotters on squat and bench, and stop at the last rep that met the standard, not the last one that moved.
Limitations
Estimates get less reliable as reps go up; a set of 3 to 5 predicts well, a set of 12 much less so, and people differ in how many reps they can do at a given percentage. Formulas also travel badly to machines and isolation exercises. A tested 1RM is a single day's number and moves with sleep, stress and the warm-up, which is why many programmes base their percentages on a training max set around 90 per cent of it rather than on the full figure. Testing frequently costs recovery and earns little.
Turning it into training loads
Percentages only work if the 1RM behind them is current and honest. With a 116kg estimated squat, 70 per cent is about 81kg and 80 per cent about 93kg; many lifters can manage something like 10 to 12 reps at the first and around 8 at the second, but the spread between individuals is wide. For that reason many programmes now pair a percentage with a target effort, such as stopping two reps short of failure, so the session adjusts on days when the 1RM is not what it was on paper.
Examples
- 315lb 1RM squat
- Training at 70% of 1RM (220lbs if 1RM is 315)
- Testing 1RM every 8-12 weeks
Related Terms
Compound exercises
Put this into practice with exercises from the library.
Common questions
What is 1RM?
The maximum weight you can lift for a single repetition with proper form. Your one-rep max (1RM) is the heaviest weight you can lift once with good technique.
What exercises train the 1RM?
Good options include Log Lift, London Bridges, Low Pulley Row To Neck, Lunge Pass Through, Lunge Sprint. Each links to a step-by-step guide with demonstration images.
What are examples of 1RM?
315lb 1RM squat; Training at 70% of 1RM (220lbs if 1RM is 315); Testing 1RM every 8-12 weeks.
Put it into practice
12-Week Muscle Building · £29
A 12-week, four-day hypertrophy plan in three phases, with a modest calorie surplus