Which 1RM formula is most accurate?

No formula is universally most accurate, results vary by individual, by lift, and by training background. Epley and Brzycki are the two most commonly cited in strength research. Averaging all five reduces the impact of any one formula's individual bias. If you periodically test your true 1RM, you can compare actual results to formula estimates and identify which formula tends to be closest for you specifically.

Is it safe to test a true 1RM?

Testing a true one rep max carries injury risk, particularly for lifters with less than one to two years of consistent training, and requires a thorough warm-up, a spotter for squat and bench press, and near-perfect technique under maximum load. Most coaches recommend estimating from 3-5 rep sets at submaximal loads. The accuracy difference is small enough that estimated 1RMs from well-executed sets are suitable for all practical programming.

How do I use the training percentage table?

Match the intensity percentage to your training goal for the week. Strength work typically uses 85-95% of 1RM for sets of 1-5 reps. Hypertrophy work sits at 65-80% for 6-12 reps. Speed and technique work often uses 50-65% to allow maximum bar speed. Use the table to select the working weight directly rather than calculating percentages by hand before each session.

Why do the five formulas give different numbers?

Each formula was derived from a different dataset and population. Epley and Lombardi are generous estimators; Brzycki and O'Connor are more conservative. The divergence is typically within 5% for sets of 3-8 reps, which is within acceptable training margin. Averaging them gives a middle estimate that is less likely to lead to loading errors in either direction.

What is the difference between a tested 1RM and an estimated 1RM for programming purposes?

A tested 1RM is a weight you have actually lifted once under controlled conditions with proper warm-up and technique. An estimated 1RM is derived from a submaximal performance using one of the formulas. For most training contexts the distinction does not matter much, programming at 80% of an estimated 1RM produces similar training stimulus to programming at 80% of a tested 1RM, assuming the estimate is reasonably accurate. The tested value may be slightly higher than the estimate because near-maximal neural drive is not fully captured by submaximal rep formulas. If you find your training percentages consistently feel lighter than they should, your actual 1RM may be higher than the estimate.

How do I warm up when working at a high training percentage?

A standard warm-up protocol for working at 85-95% of 1RM: start with an empty or light bar for 8-10 reps, then add weight in increments of 15-20% of your working weight, reducing reps as you approach the working set. Common warm-up sets: 40%, 55%, 70%, 80% of 1RM for 5, 4, 3, 2 reps respectively, then the working set. The training table in this calculator shows the weight for each percentage increment, making it straightforward to read off the bar load for each warm-up step without doing mental arithmetic between sets.

One Rep Max (1RM) Calculator

Estimate your one rep max with five proven formulas and a percentage-based training table for programming workouts.

Your set

Weight liftedReps completed

Unit

KilogramsPounds

Lift type

Estimated 1RM (average)

114.57 kg

Formula comparison

Formula	Estimated 1RM
Epley	116.67 kg
Brzycki	112.5 kg
Lander	113.71 kg
Lombardi	117.46 kg
O'Connor	112.5 kg
Average	114.57 kg

Training percentage table

%	Weight	Est. reps
50%	57.29 kg	20+
55%	63.01 kg	19
60%	68.74 kg	17
65%	74.47 kg	15
70%	80.2 kg	12
75%	85.93 kg	10
80%	91.66 kg	8
85%	97.38 kg	5
90%	103.11 kg	3
95%	108.84 kg	2
100%	114.57 kg	1

For heavy squats and deadlifts, many lifters use a belt and longer rest above 90% of estimated max.

These are estimates, not medical advice. Stop if you feel pain, dizziness, or loss of form.

How this tool works

The calculator applies five published formulas to your lifted weight (w kg or lb) and rep count (r), each modeling the fatigue curve differently. Epley: 1RM = w × (1 + r ÷ 30). Brzycki: 1RM = w × 36 ÷ (37 − r). Lander: 1RM = (100 × w) ÷ (101.3 − 13.36 × r). Lombardi: 1RM = w × r^0.10. O'Connor: 1RM = w × (1 + r ÷ 40). It then averages all five and builds a percentage table showing the estimated load for 50%–100% of your calculated 1RM, useful for programming warm-up sets. Key assumption: all formulas assume sub-maximal reps performed to failure or near-failure with full range of motion. Edge case: accuracy drops sharply above 10 reps because no formula reliably models the aerobic contribution that kicks in at higher rep ranges. For rep counts above 10, treat the estimate as a rough lower bound only. Beginners whose technique degrades before muscular failure will also see inflated 1RM estimates.

Worked example

| Formula | Calculation | Estimated 1RM | |---|---|---| | Epley | 100 x (1 + 5/30) | 116.7 kg | | Brzycki | 100 x (36 / 32) | 112.5 kg | | Lander | (100 x 100) / (101.3 - 13.36) | 113.8 kg | | Lombardi | 100 x 5^0.10 | 116.7 kg | | O'Connor | 100 x (1 + 5/40) | 112.5 kg | | Average | | 114.4 kg |

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Frequently asked questions

Which 1RM formula is most accurate?
No formula is universally most accurate, results vary by individual, by lift, and by training background. Epley and Brzycki are the two most commonly cited in strength research. Averaging all five reduces the impact of any one formula's individual bias. If you periodically test your true 1RM, you can compare actual results to formula estimates and identify which formula tends to be closest for you specifically.
Is it safe to test a true 1RM?
Testing a true one rep max carries injury risk, particularly for lifters with less than one to two years of consistent training, and requires a thorough warm-up, a spotter for squat and bench press, and near-perfect technique under maximum load. Most coaches recommend estimating from 3-5 rep sets at submaximal loads. The accuracy difference is small enough that estimated 1RMs from well-executed sets are suitable for all practical programming.
How do I use the training percentage table?
Match the intensity percentage to your training goal for the week. Strength work typically uses 85-95% of 1RM for sets of 1-5 reps. Hypertrophy work sits at 65-80% for 6-12 reps. Speed and technique work often uses 50-65% to allow maximum bar speed. Use the table to select the working weight directly rather than calculating percentages by hand before each session.
Why do the five formulas give different numbers?
Each formula was derived from a different dataset and population. Epley and Lombardi are generous estimators; Brzycki and O'Connor are more conservative. The divergence is typically within 5% for sets of 3-8 reps, which is within acceptable training margin. Averaging them gives a middle estimate that is less likely to lead to loading errors in either direction.
What is the difference between a tested 1RM and an estimated 1RM for programming purposes?
A tested 1RM is a weight you have actually lifted once under controlled conditions with proper warm-up and technique. An estimated 1RM is derived from a submaximal performance using one of the formulas. For most training contexts the distinction does not matter much, programming at 80% of an estimated 1RM produces similar training stimulus to programming at 80% of a tested 1RM, assuming the estimate is reasonably accurate. The tested value may be slightly higher than the estimate because near-maximal neural drive is not fully captured by submaximal rep formulas. If you find your training percentages consistently feel lighter than they should, your actual 1RM may be higher than the estimate.
How do I warm up when working at a high training percentage?
A standard warm-up protocol for working at 85-95% of 1RM: start with an empty or light bar for 8-10 reps, then add weight in increments of 15-20% of your working weight, reducing reps as you approach the working set. Common warm-up sets: 40%, 55%, 70%, 80% of 1RM for 5, 4, 3, 2 reps respectively, then the working set. The training table in this calculator shows the weight for each percentage increment, making it straightforward to read off the bar load for each warm-up step without doing mental arithmetic between sets.