One Rep Max Calculator

Calculate your one-rep max (1RM) for any strength training exercise. Get accurate estimates using multiple proven formulas and discover your optimal training percentages for building strength.

Weight Lifted

Repetitions

Unit

Formula Comparison

Formula	Calculation	Best For	Accuracy
Epley	Weight × (1 + 0.0333 × Reps)	3-10 reps, compound lifts	Most popular, slightly optimistic
Brzycki	Weight × 36 / (37 - Reps)	6-10 reps, powerlifting	Conservative, safer estimates
Lombardi	Weight × Reps^0.1	1-5 reps, low rep work	Good for strength athletes
O'Connor	Weight × (1 + 0.025 × Reps)	8-15 reps, beginners	Conservative, high rep ranges
Mayhew	100 × Weight / (52.2 + 41.9 × e^(-0.055 × Reps))	1-15 reps, bench press	Complex but versatile

Training Intensity Zones

Strength Development

90-100% (Max Effort)

1-3 reps | Rest: 3-5 min

Peak strength, neural adaptation

85-90% (Heavy)

3-5 reps | Rest: 3-5 min

Build max strength, technique refinement

80-85% (Moderate-Heavy)

5-8 reps | Rest: 2-3 min

Strength with some hypertrophy

Hypertrophy & Volume

70-80% (Hypertrophy)

8-12 reps | Rest: 1-2 min

Optimal muscle growth zone

60-70% (Endurance)

12-20 reps | Rest: 30-90 sec

Muscular endurance, work capacity

50-60% (Active Recovery)

15-25 reps | Rest: 30-60 sec

Deload, technique, blood flow

Power & Speed

50-70% (Explosive)

3-5 reps | Rest: 2-3 min

Speed work, rate of force development

30-50% (Speed-Strength)

3-6 reps | Rest: 2-3 min

Dynamic effort, bar speed

85-95% (Strength-Speed)

1-3 reps | Rest: 3-5 min

Heavy singles with speed focus

Rep Range Accuracy Guide

✓

3-5 Reps (Optimal)

Most accurate range for 1RM estimation. Heavy enough to reflect true strength but not so heavy that form breaks down. Use this range for reliable programming.

→

6-10 Reps (Good)

Still reliable but slightly less accurate. Muscular endurance starts to become a factor. Use Brzycki or O'Connor formulas for better estimates in this range.

⚠

11-15 Reps (Moderate)

Accuracy decreases significantly. Mental fatigue and muscular endurance become limiting factors. Use only for general estimates, not precise programming.

✗

15+ Reps (Poor)

Not recommended for 1RM estimation. Results will be highly inaccurate and unreliable for strength programming. Test with heavier weights for better estimates.

Sample 12-Week Periodization

Example of how to use 1RM percentages in a structured strength program:

Weeks 1-3: Accumulation

70-75% × 8-10 reps

4 sets per exercise

Build work capacity and volume tolerance

Weeks 4-6: Intensification

80-85% × 5-6 reps

4-5 sets per exercise

Increase intensity, maintain volume

Weeks 7-9: Realization

85-92% × 3-4 reps

3-4 sets per exercise

Peak strength development

Weeks 10-12: Peaking

90-95% × 1-3 reps

2-3 sets per exercise

Test new 1RM in week 12

Critical Testing Guidelines

1.
Warm up progressively:Empty bar × 10, 50% × 5, 70% × 3, 85% × 1, then test weight
2.
Test when fresh:First exercise of the day, after 2-3 days rest, well-fed and hydrated
3.
Maintain strict form:Only count reps with proper technique - no partial reps or form breakdown
4.
Use consistent exercise variations:Compare apples to apples - same grip width, bar path, depth, etc.
5.
Test infrequently:True 1RM attempts only 2-4 times per year - use calculated estimates for regular training

Common Programming Errors

Training at exact percentages without autoregulation

Your daily readiness varies. If 80% feels like 90% on a given day, adjust the load. Use RPE (Rate of Perceived Exertion) alongside percentages to account for sleep, stress, and recovery status.

Testing 1RM too frequently

Maxing out is neurally demanding and increases injury risk. Test actual 1RM only at the end of training cycles. Use submaximal estimates (3-5 reps) for regular programming adjustments.

Ignoring exercise specificity

Your 1RM for competition squat differs from high-bar squat, which differs from front squat. Track 1RMs separately for each variation you train regularly. Don't assume carryover is 1:1.

Using high-rep sets for estimation

Sets of 15-20 reps are poor predictors of 1RM. Muscular endurance and mental fatigue become limiting factors. Always test with 3-8 reps for reliable estimates, with 3-5 being optimal.

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Formula Comparison

Formula	Calculation	Best For	Accuracy
Epley	Weight × (1 + 0.0333 × Reps)	3-10 reps, compound lifts	Most popular, slightly optimistic
Brzycki	Weight × 36 / (37 - Reps)	6-10 reps, powerlifting	Conservative, safer estimates
Lombardi	Weight × Reps^0.1	1-5 reps, low rep work	Good for strength athletes
O'Connor	Weight × (1 + 0.025 × Reps)	8-15 reps, beginners	Conservative, high rep ranges
Mayhew	100 × Weight / (52.2 + 41.9 × e^(-0.055 × Reps))	1-15 reps, bench press	Complex but versatile

Training Intensity Zones

Strength Development

90-100% (Max Effort)

1-3 reps | Rest: 3-5 min

Peak strength, neural adaptation

85-90% (Heavy)

3-5 reps | Rest: 3-5 min

Build max strength, technique refinement

80-85% (Moderate-Heavy)

5-8 reps | Rest: 2-3 min

Strength with some hypertrophy

Hypertrophy & Volume

70-80% (Hypertrophy)

8-12 reps | Rest: 1-2 min

Optimal muscle growth zone

60-70% (Endurance)

12-20 reps | Rest: 30-90 sec

Muscular endurance, work capacity

50-60% (Active Recovery)

15-25 reps | Rest: 30-60 sec

Deload, technique, blood flow

Power & Speed

50-70% (Explosive)

3-5 reps | Rest: 2-3 min

Speed work, rate of force development

30-50% (Speed-Strength)

3-6 reps | Rest: 2-3 min

Dynamic effort, bar speed

85-95% (Strength-Speed)

1-3 reps | Rest: 3-5 min

Heavy singles with speed focus

Rep Range Accuracy Guide

✓

3-5 Reps (Optimal)

Most accurate range for 1RM estimation. Heavy enough to reflect true strength but not so heavy that form breaks down. Use this range for reliable programming.

→

6-10 Reps (Good)

Still reliable but slightly less accurate. Muscular endurance starts to become a factor. Use Brzycki or O'Connor formulas for better estimates in this range.

⚠

11-15 Reps (Moderate)

Accuracy decreases significantly. Mental fatigue and muscular endurance become limiting factors. Use only for general estimates, not precise programming.

✗

15+ Reps (Poor)

Not recommended for 1RM estimation. Results will be highly inaccurate and unreliable for strength programming. Test with heavier weights for better estimates.

Sample 12-Week Periodization

Example of how to use 1RM percentages in a structured strength program:

Weeks 1-3: Accumulation

70-75% × 8-10 reps

4 sets per exercise

Build work capacity and volume tolerance

Weeks 4-6: Intensification

80-85% × 5-6 reps

4-5 sets per exercise

Increase intensity, maintain volume

Weeks 7-9: Realization

85-92% × 3-4 reps

3-4 sets per exercise

Peak strength development

Weeks 10-12: Peaking

90-95% × 1-3 reps

2-3 sets per exercise

Test new 1RM in week 12

Critical Testing Guidelines

Warm up progressively:Empty bar × 10, 50% × 5, 70% × 3, 85% × 1, then test weight

Test when fresh:First exercise of the day, after 2-3 days rest, well-fed and hydrated

Maintain strict form:Only count reps with proper technique - no partial reps or form breakdown

Use consistent exercise variations:Compare apples to apples - same grip width, bar path, depth, etc.

Test infrequently:True 1RM attempts only 2-4 times per year - use calculated estimates for regular training

Common Programming Errors

Training at exact percentages without autoregulation

Your daily readiness varies. If 80% feels like 90% on a given day, adjust the load. Use RPE (Rate of Perceived Exertion) alongside percentages to account for sleep, stress, and recovery status.

Testing 1RM too frequently

Maxing out is neurally demanding and increases injury risk. Test actual 1RM only at the end of training cycles. Use submaximal estimates (3-5 reps) for regular programming adjustments.

Ignoring exercise specificity

Your 1RM for competition squat differs from high-bar squat, which differs from front squat. Track 1RMs separately for each variation you train regularly. Don't assume carryover is 1:1.

Using high-rep sets for estimation

Sets of 15-20 reps are poor predictors of 1RM. Muscular endurance and mental fatigue become limiting factors. Always test with 3-8 reps for reliable estimates, with 3-5 being optimal.