How To Calculate Your One Rep Max

What Is Your One Rep Max?

Your one rep max (1RM) is the maximum weight you can lift for a single repetition with good form. It's the foundation of percentage-based strength programming, knowing your 1RM allows you to calculate precise training weights for every rep range and intensity zone.

Directly testing your 1RM carries injury risk and requires significant recovery time. Estimating from a sub-maximal set (a weight you can lift for 2-10 reps) is safer and accurate enough for programming purposes.

The Best Formulas

Seven formulas are commonly used to estimate 1RM from sub-maximal sets. The average of all seven is more accurate than any single formula:

Formula	Best For	Notes
Epley	General use	Most widely used, good all-rounder
Brzycki	Low reps (1-10)	Most accurate for heavy sets
Lander	Mid-range	Good intermediate accuracy
Lombardi	Higher estimates	Tends to produce slightly higher numbers
Mayhew	Higher reps	Better accuracy for 10+ rep sets
O'Conner	Conservative	Simple, slightly lower estimates
Wathan	Higher reps	Good accuracy above 10 reps

Training Percentage Zones

Once you know your 1RM, you can prescribe exact training weights for different goals. Each percentage zone produces different physiological adaptations:

Zone	% of 1RM	Reps	Adaptation
Absolute Strength	90-100%	1-3	Neural efficiency, max strength
Strength	80-90%	3-5	Strength + muscle
Strength-Hypertrophy	70-80%	6-8	Balanced strength and size
Hypertrophy	60-70%	8-12	Muscle size, optimal range
Endurance	50-60%	12-20	Conditioning, warm-up

How Often To Test

Recalculate your 1RM estimate every 4-8 weeks. Rather than maxing out directly, take a rep PR at any weight and plug it into the calculator. If you lifted 100kg for 8 reps last month and now lift it for 10 reps, your 1RM has increased, recalculate and update your training weights accordingly.

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One Rep Max Calculator

Calculate your 1RM from any rep range using 7 formulas with full training percentage tables.

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Frequently Asked Questions

Testing your true 1RM carries higher injury risk than sub-maximal training. For most people, estimating from a 3-5 rep set is accurate enough and far safer. If you do test directly, always use a spotter on pressing movements, use a squat rack with safeties, and ensure your technique is solid.

Accuracy decreases as rep count increases. Sets of 1-5 reps produce estimates within 2-5% of actual 1RM. Sets above 10 reps should be treated as rough guides only, as muscular endurance factors start to dominate over pure strength.

As a benchmark for men: Squat 1.5- bodyweight (intermediate), 2- (advanced). Bench 1- bodyweight (intermediate), 1.5- (advanced). Deadlift 2- bodyweight (intermediate), 2.5- (advanced). Women's standards are roughly 65-70% of these.

No, training too close to your 1RM every session leads to accumulated fatigue and injury risk. Most effective programming uses a variety of intensities. A common approach: one heavy day (80-90%), one moderate day (70-80%), one lighter day (60-70%) per movement pattern per week.