One Rep Max (1RM) Calculator

Your One Rep Max (1RM) is the absolute maximum weight you can lift for a single repetition of an exercise with proper form. It's the gold standard metric for measuring absolute strength and serves as the foundation for intelligent training programming.

Whether you're a powerlifter, weightlifter, CrossFit athlete, or recreational gym-goer, knowing your 1RM helps you:

• Program optimal training loads — Most proven strength programs prescribe weights as % of 1RM (e.g., "5×5 at 80%").
• Track progress objectively — Your 1RM is a clear, quantifiable measure of strength gains over time.
• Ensure progressive overload — Knowing your max lets you systematically increase training stimulus.
• Avoid under- or over-training — Training at the right intensity prevents plateau and reduces injury risk.

Different formulas were developed through research on various populations (powerlifters, athletes, general population). Here's what you need to know:

Pro tip: Use our calculator to see all formulas at once. If they're all within 5-10% of each other, you have a reliable estimate. Large discrepancies may indicate form breakdown or rep counting issues.

Once you know your 1RM, you can program training using percentages. Each percentage range targets different physiological adaptations:

Example: If your 1RM squat is 300 lbs and you're doing a hypertrophy block at 75%, you'd work with 225 lbs for sets of 8-10 reps.

When to Test

• End of training blocks — Test every 4-8 weeks after a strength or peaking cycle.
• After adequate recovery — Be well-fed, well-rested (2-3 rest days), not in a deficit.
• Not during deload — Wait until you're fresh and primed, not fatigued.

How to Test Safely

• Use a 3-5 rep max — Safer and equally accurate when using formulas.
• Proper warm-up — Start with dynamic stretches, then progressive weight jumps (bar → 50% → 70% → 85% → test).
• Perfect form only — If form breaks down, the rep doesn't count. No grinding ugly reps.
• Use a spotter — Especially for bench press and squats.
• Don't test when injured — This seems obvious but needs to be said.

Common Mistakes to Avoid

• Testing too frequently — You can't set a new PR every week. Testing is fatiguing.
• Using estimated 1RM for true max attempts — The calculator gives you training numbers, not an invitation to ego-lift.
• Poor form on test sets — Half-squats and bounced bench reps invalidate the data.
• Not accounting for fatigue — Your 1RM will be lower if tested after high-volume training.

1RM is most relevant for compound, barbell lifts where you can safely progress weight and measure strength:

Primary Lifts (Track These)

• Squat (Back Squat) — King of lower body strength
• Bench Press — Upper body pressing standard
• Deadlift (Conventional or Sumo) — Total body pulling power
• Overhead Press — Shoulder and pressing strength

Accessory Lifts (Optional)

• Front Squat, Romanian Deadlift, Incline Bench
• Olympic lifts (Clean, Snatch) — though technique matters more than raw strength

Don't Bother With

• Isolation exercises (bicep curls, lateral raises) — not strength-focused
• Machines — variable resistance, less standardized
• Bodyweight exercises — unless you're adding external load

Can I use this for Olympic lifts?

While you can, Olympic lifts (snatch, clean & jerk) are more technique-dependent than strength-dependent. A true 1RM test is more appropriate than formula estimates. For training, coaches often program based on competition maxes or recent best lifts rather than calculated 1RMs.

Do women and men use the same formulas?

Yes. The formulas are based on the relationship between sub-maximal and maximal effort, which is similar across sexes. However, women may have slightly better muscular endurance relative to their 1RM, meaning higher-rep estimates might be marginally more conservative.

Why do different formulas give different results?

Each formula was developed using different research populations and methods. Some are more aggressive, some more conservative. The variation is usually 5-10%. Use the average or the formula that has historically matched your actual tested 1RM best.

How quickly can I increase my 1RM?

Beginners can add 5-10 lbs per month to major lifts. Intermediate lifters may see 2-5 lbs per month. Advanced lifters often measure progress in 5-10 lb increases per year. Progress slows as you approach your genetic ceiling, which is why smart programming and patience are critical.

• National Strength and Conditioning Association (NSCA) — Certifying body for strength coaches; extensive 1RM research and guidelines.
• Stronger By Science — Evidence-based strength training research and education.
• PubMed / NCBI — Peer-reviewed research on 1RM testing protocols and formula validation.

All formulas used in this calculator are cited in peer-reviewed literature and are standard tools in strength and conditioning.