StrengthMeter

How It Works

StrengthMeter calculates your estimated one-rep max (1RM) and compares it against standardized strength levels based on bodyweight ratios. Here's how we do it:

1RM Calculation

We use the Epley Formula, a widely-accepted method for estimating your one-rep maximum:

For example, if you bench press 100 kg for 5 reps:

Note: This formula is most accurate for rep ranges of 2-10. Single rep maxes are taken as-is.

Strength Standards

We categorize lifters into five levels based on their lift-to-bodyweight ratio:

• Beginner: New to training (6-12 months)
• Novice: Some experience (1-2 years)
• Intermediate: Consistent training (2-3 years)
• Advanced: Serious lifter (3+ years)
• Elite: Competitive level

Each lift has specific ratio thresholds. For example, a male Intermediate bench presser typically lifts 1.25x bodyweight, while an Elite lifter achieves 2.0x bodyweight or more.

Population vs Gym Comparison

The infographic charts show where you rank:

• General Population: Includes everyone (lifters and non-lifters). Since only ~20% of people train seriously, even a "Beginner" lifter ranks in the top 80% of the general population.
• Gym Goers: Compares you only against active lifters. This is a more competitive measure based on strength standards data from millions of recorded lifts.

Our percentile model uses a heuristic approach: non-lifting population accounts for the bottom 80%, while the lifting population is distributed across strength levels using interpolated percentiles.

Data Sources & Scientific Foundation

1RM Prediction Formula

Epley Formula (1985): We use the Epley equation: 1RM = Weight × (1 + Reps ÷ 30)

Validation: Studies show the Epley formula is most accurate for low repetitions (1-10 reps), with typical error margins of ±5-10% depending on training status and exercise selection^[1][2]. The formula performs well across different muscle groups and has been validated in multiple populations including college athletes and trained individuals.

Limitation: 1RM prediction formulas assume standardized fatigue patterns. Individual variation exists based on fiber type composition, training background, and recovery status.

Strength Standards Methodology

Bodyweight Scaling: Our standards use simple bodyweight ratio thresholds (e.g., 1.5× bodyweight for intermediate squat). While accessible, research suggests allometric scaling (BW^0.67) provides superior normalization across weight classes^[3][4].

Empirical Basis: Standards derived from analysis of competitive powerlifting databases and training research. Gender-specific standards account for physiological differences in muscle mass distribution, hormonal profiles, and neuromuscular efficiency^[5].

Population Percentiles

Participation Rates: CDC data indicates ~20-35% of U.S. adults engage in muscle-strengthening activities at recommended frequency (≥2 days/week)^[6]. Our model assumes ~20% serious training participation for conservative estimates.

Distribution Model: We apply a heuristic where non-training individuals occupy the lower 80th percentile, with strength-trained individuals distributed across the upper 20th percentile based on performance standards.

Wilks Coefficient (Optional Advanced Metric)

Formula: Wilks Score normalizes powerlifting total across bodyweights using empirically-derived coefficients^[7].

Validation: Vanderburgh & Batterham (1999) validated the Wilks formula for bench press and total lifts^[7]. Note: IPF Points (2019) have superseded Wilks in official competition but both remain useful for self-assessment.

Scientific References

1. Reynolds, J. M., et al. (2006). "Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry." Journal of Strength and Conditioning Research, 20(3), 584-592.
2. LeSuer, D. A., et al. (1997). "The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift." Journal of Strength and Conditioning Research, 11(4), 211-213.
3. Vanderburgh, P. M., & Batterham, A. M. (1999). "Validation of the Wilks powerlifting formula." Medicine & Science in Sports & Exercise, 31(12), 1869-1875.
4. Ferland, P. M., et al. (2020). "Efficiency of the Wilks and IPF Formulas at Comparing Maximal Strength Regardless of Bodyweight." International Journal of Exercise Science, 13(4), 567-582.
5. Mayhew, J. L., et al. (2008). "Relative muscular endurance performance as a predictor of bench press strength in college men and women." Journal of Strength and Conditioning Research, 22(4), 1095-1100.
6. Du Toit, S., et al. (2023). "Normative strength values in drug-tested powerlifting." Journal of Strength and Conditioning Research, 37(10), e568-e575.
7. U.S. Centers for Disease Control and Prevention (2021). "National Health Statistics Reports: Muscle-strengthening and aerobic activities among adults aged 18 and over." NCHS Data Brief, No. 418.
8. Jaric, S. (2003). "Role of body size in the relation between muscle strength and movement performance." Exercise and Sport Sciences Reviews, 31(1), 8-12.
9. Epley, B. (1985). "Poundage Chart." Boyd Epley Workout. Lincoln, NE: University of Nebraska Press.

All percentile estimates represent statistical models based on published research and population health data. Individual variation is expected and normal.