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One Rep Max Calculator

Epley ยท Brzycki ยท Lombardi ยท O'Conner ยท Full % table ยท Training zones ยท Bar chart

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Formula

๐Ÿ‹๏ธ Enter the weight you lifted and how many reps you completed to estimate your one rep maximum across four formulas.

The Four 1RM Formulas

All four major 1RM estimation formulas take weight lifted (W) and repetitions completed (R) as inputs. They were derived from research on competitive and recreational lifters and differ in how they extrapolate from submaximal effort to a theoretical maximum.

Epley (1985)

1RM = W ร— (1 + R / 30) Boyd Epley, University of Nebraska. Most commonly used formula. Example: 185 lbs ร— 5 reps: 185 ร— (1 + 5/30) = 185 ร— 1.167 = 215.9 lbs

Brzycki (1993)

1RM = W ร— (36 / (37 - R)) Matt Brzycki. Produces the same result as Epley at R=10; lower estimates at low reps. Example: 185 lbs ร— 5 reps: 185 ร— 36/(37-5) = 185 ร— 1.125 = 208.1 lbs Note: undefined if R โ‰ฅ 37

Lombardi (1989)

1RM = W ร— R^0.10 Lombardi. Uses a power function rather than linear scaling. Example: 185 lbs ร— 5 reps: 185 ร— 5^0.10 = 185 ร— 1.175 = 217.4 lbs

O'Conner (1989)

1RM = W ร— (1 + R / 40) O'Conner et al. Similar to Epley but with a smaller multiplier (40 vs 30). Example: 185 lbs ร— 5 reps: 185 ร— (1 + 5/40) = 185 ร— 1.125 = 208.1 lbs Tends to produce lower 1RM estimates than Epley, especially at higher rep counts.

Training Intensity Zones

Once you know your estimated 1RM, you can use percentages of that number to guide training load for specific goals. These zones are based on research in exercise science and strength and conditioning practice.

Power / Speed
50 to 65%
3 to 5 reps
Bar speed maximised. Develops rate of force development and explosive power.
Hypertrophy
67 to 80%
8 to 12 reps
Primary muscle size range. High metabolic stress and mechanical tension.
Strength
80 to 90%
3 to 6 reps
Neurological adaptations. Increased motor unit recruitment and rate coding.
Maximal
90 to 100%
1 to 3 reps
Near-maximal loads. Peak neural drive. Competition prep or 1RM testing only.
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Most well-designed strength programmes use percentages across multiple zones within a week or training block (periodisation). A common split is 80% of volume in the hypertrophy and strength zones and 20% in the power or maximal zones. Training exclusively at one percentage risks plateau and overuse injury.

Estimating 1RM vs Directly Testing It

Using Estimation Formulas (Recommended for Most Lifters)

Estimation methods use a submaximal lift - a weight that causes failure between 3 and 10 repetitions - and extrapolate to the theoretical maximum. The major advantages are lower injury risk, faster assessment, and accessibility for beginners.

Accuracy is best when the rep count is between 1 and 6. At 10 reps, most formulas agree within 2 to 3%. Above 10 reps, the formulas diverge significantly and endurance begins to affect the result, making estimates unreliable. For programming purposes, aim to test at 3 to 5 reps for the best balance of safety and accuracy.

Direct 1RM Testing

Direct testing involves progressively increasing weight until only one full repetition with proper form can be completed. Steps:

  1. Warm up thoroughly - 5 to 10 minutes of general activity plus 2 to 3 warm-up sets at progressively increasing weights.
  2. Find a spotter for all overhead and bar-over-body exercises (bench press, squat, overhead press).
  3. Start at a weight you can lift for 5 to 6 reps comfortably.
  4. Rest 3 to 5 minutes fully between attempts.
  5. Increase weight by 5 to 10% per attempt until one rep maximum is reached.
  6. Record the highest weight completed with full range of motion and proper form.
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Direct 1RM testing carries meaningful injury risk. It is not appropriate for beginners, people with joint injuries, or those with less than 3 to 6 months of consistent lifting experience. Estimation from a 3 to 5 rep set is safer, nearly as accurate, and requires no spotter in most cases.

Formula Accuracy by Rep Count

Reps UsedEstimated AccuracyRecommended?
1Actual 1RMOnly with experienced spotter
2 to 3Within 2 to 5%Yes - very accurate, low injury risk
4 to 6Within 5 to 8%Yes - best practical range
7 to 10Within 8 to 12%Acceptable
11 to 15Within 12 to 20%Poor - formulas diverge significantly
Above 15Very unreliableNo - endurance dominates

Using 1RM to Programme Training

The value of 1RM is in the percentages. Once you have an estimated or tested 1RM, you can prescribe specific training loads for each goal zone without having to guess whether the weight is appropriate.

Example: 5ร—5 Programme at 80% 1RM

For an estimated 1RM of 225 lbs on bench press: 80% = 180 lbs. Programme 5 sets of 5 reps at 180 lbs. As strength improves and the 5ร—5 at 180 lbs becomes more manageable, recalculate 1RM and advance the load. This wave-loading approach drives steady progress while managing fatigue.

Warm-Up Set Structure

Set% of Working WeightRepsPurpose
Warm-up 140 to 50%10 to 12Joint lubrication, motor pattern
Warm-up 260 to 65%5 to 6Neuromuscular activation
Warm-up 375 to 80%2 to 3Prepare CNS for working weight
Working sets100% of planned loadPrescribedStimulus for adaptation

Frequently Asked Questions

How often should I test my 1RM?
For intermediate lifters, testing or re-estimating 1RM every 4 to 8 weeks is practical. Beginners gain strength so rapidly that their 1RM may change every 1 to 2 weeks, making frequent testing impractical - use estimated 1RM from your most recent working sets instead. Advanced lifters typically peak and test 1RM at the end of structured training blocks of 8 to 16 weeks. Frequent maximal testing between competitive periods drains neural reserves without adding meaningful training stimulus.
Should I use the same 1RM for all exercises?
No. 1RM is specific to each exercise because different movements engage different muscle groups, leverage ratios, and technique demands. Your bench press 1RM has no bearing on your squat 1RM. Always estimate or test 1RM separately for each lift you want to programme with precision - bench press, squat, deadlift, overhead press, and any other primary movement in your programme.
Why do the formulas give different results?
Each formula was derived from a different research population and uses a different mathematical model for the relationship between rep count and strength. Epley and O'Conner use linear scaling (weight ร— (1 + reps/30 or 40)). Brzycki uses a ratio formula derived from percentage tables. Lombardi uses a power function (weight ร— reps^0.10). They agree most closely at 1 to 3 reps and diverge progressively at higher rep counts. Using the average of all four reduces sensitivity to any single formula's assumptions.
What is a good 1RM for bench press, squat, and deadlift?
Strength standards vary by bodyweight, sex, age, and training experience. General benchmarks for a trained adult male as a multiple of bodyweight: bench press 1.0 to 1.5ร— (intermediate to advanced), squat 1.5 to 2.0ร—, deadlift 1.75 to 2.25ร—. For trained adult females the standards are approximately 0.7 to 1.0ร— bodyweight for bench, 1.0 to 1.5ร— for squat, 1.25 to 1.75ร— for deadlift. These are rough guidelines - absolute strength depends strongly on leverages, training age, and genetic factors.