Estimate the maximum weight you can lift for one rep — using 6 proven formulas averaged for accuracy.
Units
Your Estimated 1RM
—kg
Estimated One-Rep Max
Average of 6 formulas
⚠ Estimates become less accurate above 10–12 reps. For best results, use a weight you can lift for 1–10 reps.
Formula
Estimated 1RM
Variance
Training Percentages
% of 1RM
Weight
Typical Reps
Training Zone
These estimates are most accurate when based on 1–10 reps with a weight that challenges you to near-failure.
What Is a One-Rep Max?
Your one-rep max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's the gold standard for measuring absolute strength and serves several practical purposes:
Programming training percentages — Most strength programs prescribe loads as a percentage of your 1RM (e.g., "5×5 at 80%").
Tracking progress — A rising estimated 1RM confirms your training is working, even if you never test a true max.
Comparing strength levels — 1RM relative to bodyweight lets you benchmark yourself against standardized strength tables.
Directly testing your 1RM carries injury risk and requires peak readiness. Submaximal estimation — lifting a lighter weight for multiple reps and calculating from there — is safer, more practical, and something you can do any training session.
Historical note: The concept of percentage-based training dates back to 1960s Soviet weightlifting programs. Coach A.S. Prilepin analyzed thousands of training logs to create "Prilepin's Chart" — a table of optimal sets, reps, and intensity zones that remains the foundation of modern strength programming over 60 years later.
How 1RM Formulas Work
All 1RM formulas model a mathematical relationship between the weight lifted and the number of reps performed. They assume that as reps increase, the weight you can handle decreases in a predictable curve. Each formula fits that curve slightly differently:
Formula
Best For
Tendency
Epley
General use, most widely cited
Slightly overestimates for trained lifters
Brzycki
Rep ranges 1–10
Slightly conservative, good for intermediates
Lander
Moderate rep ranges
Good middle ground between Epley and Brzycki
Lombardi
Power-based lifts
Uses an exponential model
O'Conner
Quick estimation
Simple linear model, less accurate at extremes
Wathan
Higher rep ranges (8–15)
Most accurate for endurance-style sets
No single formula is universally best — accuracy varies by exercise, rep range, and individual training level. This calculator averages all six to produce the most reliable estimate possible.
Research: A 2004 study by LeSuer et al. compared 7 prediction formulas against actual 1RM tests across bench press, squat, and deadlift. They found that no single formula was universally superior — accuracy varied by exercise and individual. Using an average of multiple formulas (as this calculator does) consistently produced more reliable estimates than any single formula alone.
Strength Standards
These approximate standards express 1RM as a multiple of bodyweight (BW). They provide a rough benchmark for where you stand — not an absolute target.
Level
Bench Press
Squat
Deadlift
OHP
Beginner
0.5× BW
0.75× BW
1× BW
0.35× BW
Intermediate
1× BW
1.5× BW
1.75× BW
0.65× BW
Advanced
1.5× BW
2× BW
2.5× BW
1× BW
Elite
2× BW
2.5× BW
3× BW
1.25× BW
These numbers are rough guidelines that vary by sex, age, and bodyweight class. They're most useful as directional benchmarks — not strict pass/fail thresholds.
Why bodyweight ratios? Absolute strength scales with body size. A 60 kg person benching 90 kg (1.5× BW) is relatively stronger than a 120 kg person benching 150 kg (1.25× BW), even though the absolute weight is lower. Bodyweight ratios normalize for size and give a fairer comparison.
Tips for Increasing Your 1RM
Progressive overload. Add weight or reps systematically each session or week — not randomly. Even 1 kg per week on bench press adds up to 50 kg in a year.
Train specifically. To get better at heavy singles, train in the 80–95% range regularly. Strength is a skill that requires practice at high intensities.
Technique first. A 5% improvement in bar path, bracing, or leg drive can translate to a 10%+ strength increase with zero additional muscle.
Rest between heavy sets. Take 3–5 minutes between sets of 1–5 reps. Full ATP recovery is critical for maximal force production.
Eat enough protein. 1.6–2.2 g per kg bodyweight is the evidence-based range for strength athletes. Spread intake across 3–4 meals.
Sleep 7–9 hours. Growth hormone peaks during deep sleep, and sleep deprivation directly reduces strength output by 5–10%.
Deload every 4–6 weeks. Reduce volume and intensity by 40–60% for one week. Fatigue masks fitness — you'll often hit PRs the week after a deload.
Don't test 1RM too often. Every 8–12 weeks is sufficient. Frequent maxing accumulates fatigue without building strength.
Fuel Your Strength Training
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