How to Calculate 1RM: Epley and Brzycki Formulas

Here is how to calculate 1RM: do a hard set of 3–10 reps, then use the Epley formula: 1RM = weight × (1 + reps ÷ 30). For example, 225 lb for 5 reps gives an estimated max of about 262 lb. You rarely need to test a true one-rep max.

Key takeaways

• Estimate your 1RM from a set of 3–10 reps taken close to failure. Accuracy drops above about 10 reps.
• Epley and Brzycki are the two most common formulas. They agree closely at 10 reps and differ by a few percent at lower reps.
• Pick one formula and use it every time, so your progress tracking stays consistent.
• A %1RM table turns your estimate into training loads for any rep target.
• Machines, isolation lifts and trained lower-body lifters often beat the table's rep predictions.

What is a 1RM?

Your 1RM, or one-repetition maximum, is the heaviest weight you can lift once with good form. It is the standard yardstick for strength and the basis of percentage-based programs.

Testing a true max is unnecessary for most people. It is fatiguing, carries more risk and takes skill to do well. An estimate from a submaximal set is close enough for programming.

How to calculate 1RM: the formulas

Both formulas use the same two inputs: w is the weight lifted and r is the reps completed.

• Epley: 1RM = w × (1 + r / 30)
• Brzycki: 1RM = w × 36 / (37 − r)

Epley tends to give slightly higher numbers for sets of 2–9 reps. At 10 reps the two formulas give the same result.

Multipliers by rep count

To skip the math, multiply your weight by the factor for your reps.

• 3: Epley multiplier 1.100, Brzycki multiplier 1.059
• 5: Epley multiplier 1.167, Brzycki multiplier 1.125
• 8: Epley multiplier 1.267, Brzycki multiplier 1.241
• 10: Epley multiplier 1.333, Brzycki multiplier 1.333

How to calculate 1RM from 5RM

A 5-rep max is the most common starting point. It is heavy enough to be accurate and light enough to be safe.

Example: 225 lb × 5 reps

• Epley: 225 × (1 + 5/30) = 225 × 1.167 = 262.5 lb
• Brzycki: 225 × 36 / 32 = 225 × 1.125 = 253.1 lb

In metric: 100 kg × 5 gives 116.7 kg with Epley and 112.5 kg with Brzycki.

How to calculate 1RM from 3RM

Sets of 3 are closest to a true max, so the estimate is tight. The two formulas differ by only about 4%.

Example: 275 lb × 3 reps

• Epley: 275 × (1 + 3/30) = 275 × 1.100 = 302.5 lb
• Brzycki: 275 × 36 / 34 = 275 × 1.059 = 291.2 lb

How to calculate 1RM from 10RM

At 10 reps, both formulas give the same answer. Beyond 10 reps, accuracy drops, because endurance starts to limit the set more than strength.

Example: 135 lb × 10 reps

• Epley: 135 × (1 + 10/30) = 135 × 1.333 = 180 lb
• Brzycki: 135 × 36 / 27 = 135 × 1.333 = 180 lb

How to calculate 1RM for bench press

The bench press works exactly the same way. Use a set of 3–8 reps with a spotter or safety pins.

Example: 185 lb × 8 reps

• Epley: 185 × (1 + 8/30) = 185 × 1.267 = 234.3 lb
• Brzycki: 185 × 36 / 29 = 185 × 1.241 = 229.7 lb

Round to the nearest available plate jump. Here, call it about 230 lb.

What if the set wasn't to failure?

The formulas assume you couldn't do another rep. If you stopped short, add your reps in reserve to the rep count first.

For example, 100 kg for 5 reps with 2 reps left (RPE 8) is treated as 7 reps. Epley gives 100 × (1 + 7/30) = 123.3 kg. See RPE and RIR for how to rate a set honestly. Beginners tend to underestimate their reps in reserve, so the estimate works best with sets taken close to failure.

The %1RM table: from max to training loads

Once you have an estimate, use it to set loads. This table shows the average number of reps most people can do at each percentage, based on NSCA data. The last column shows loads for a 200 lb max.

• 100%: Max reps (average) 1, Load if 1RM = 200 lb 200 lb
• 95%: Max reps (average) 2, Load if 1RM = 200 lb 190 lb
• 93%: Max reps (average) 3, Load if 1RM = 200 lb 186 lb
• 90%: Max reps (average) 4, Load if 1RM = 200 lb 180 lb
• 87%: Max reps (average) 5, Load if 1RM = 200 lb 174 lb
• 85%: Max reps (average) 6, Load if 1RM = 200 lb 170 lb
• 83%: Max reps (average) 7, Load if 1RM = 200 lb 166 lb
• 80%: Max reps (average) 8, Load if 1RM = 200 lb 160 lb
• 77%: Max reps (average) 9, Load if 1RM = 200 lb 154 lb
• 75%: Max reps (average) 10, Load if 1RM = 200 lb 150 lb
• 70%: Max reps (average) 11, Load if 1RM = 200 lb 140 lb
• 67%: Max reps (average) 12, Load if 1RM = 200 lb 134 lb
• 65%: Max reps (average) 15, Load if 1RM = 200 lb 130 lb

This is an average, not a law. Trained lifters and lower-body lifts often get more reps at a given percentage. Machines and isolation exercises usually allow many more.

How to work out a 1 rep max: estimate or test?

There are four practical ways to find your max.

• Formula estimate: How Hard set of 3–10, apply Epley or Brzycki, Best for Most lifters, most of the time
• RPE-based estimate: How Weight, reps and RPE, read from an RPE chart, Best for Lifters who train with RPE
• Bar-speed (VBT): How Sensor measures bar velocity; slower reps sit closer to max, Best for Athletes with equipment
• Direct test: How Work up to a true single, Best for Competitive lifters, peaking phases

Bar speed gives a further clue. At failure, the bar reaches a minimum velocity of about 0.3 m/s in the squat and 0.15–0.2 m/s in the bench and deadlift.

If you do test a true max, use safety bars or a spotter. For the squat, set safeties just below the bottom position. For the bench, use pins just below chest height.

How to apply this

Use these steps to estimate your max and turn it into a plan.

• Warm up well. Do a few light, gradually heavier sets of the lift.
• Pick a test weight. Choose a load you think you can lift 3–8 times.
• Do one hard set. Stop when you're at failure or one rep short, with good form.
• Adjust for reserve. Add any reps you had left to your rep count.
• Apply one formula. Use Epley or Brzycki, and write down which one.
• Set training loads. Use the %1RM table. For strength, train at 80% or more for 1–6 reps.
• Re-estimate every block. Repeat the test at the end of each 3–6 week training block to track progressive overload and update loads.

If your goal is size rather than max strength, the exact number matters less. Most rep ranges for muscle growth work if sets are hard. Percentages matter most in percentage-based periodization.

FAQ

What is the formula to calculate 1RM?

The most common is the Epley formula: 1RM = weight × (1 + reps ÷ 30). The Brzycki formula is 1RM = weight × 36 ÷ (37 − reps). Use a set of 3–10 reps taken close to failure for the best accuracy.

How do you calculate 1RM from a 5RM?

Multiply your 5-rep weight by 1.167 (Epley) or 1.125 (Brzycki). For example, 225 lb for 5 gives about 262 lb with Epley and 253 lb with Brzycki. Use the same formula each time you retest.

How do you calculate 1RM from a 10RM?

Multiply your 10-rep weight by 1.333. Both Epley and Brzycki give the same result at 10 reps. For example, 135 lb for 10 reps gives an estimated max of 180 lb.

How accurate are 1RM calculators?

They are reasonably accurate for sets of 3–10 reps taken close to failure. Accuracy drops above about 10 reps. Results also vary by lift and person, since some people get more reps at a given percentage than the average.

Is it safe to test a true 1RM?

It can be, with good technique, a proper warm-up and safety bars or a spotter. For most people it is unnecessary, because a formula estimate is close enough for programming. Estimating also causes less fatigue.

Sources

• Haff GG, Triplett NT (eds.). 2016. Essentials of Strength Training and Conditioning, 4th ed. NSCA / Human Kinetics.
• Helms E, Morgan A, Valdez A. 2019. The Muscle and Strength Pyramids: Training, 2nd ed.

The 1RM formulas are easy to forget mid-session. The Field Manual puts Epley, Brzycki and every other key training formula on a single formula sheet, alongside worked examples you can copy.