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One‑Rep Max (1RM) Calculator - Online Lifting Progress

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Estimates for reps > 12 may be less accurate. Formulas work best within 1–10 reps.

Estimated One-Rep Max

113.3 kg

Average of 6 proven formulas

Formula Comparison
Formula 1RM Deviation
Find Your Training Weight

Already know your 1RM? Find how much weight to use for a target number of reps.

kg

Recommended Training Weight

85.7 kg

for 5 reps using Epley formula

Training Percentages

Based on your estimated 1RM

%1RM Weight Training Goal
Training Zones Guide
95%+ Max Strength / Peaking
85-95% Strength Focus
75-85% Strength & Hypertrophy
65-75% Hypertrophy Focus
50-65% Endurance & Recovery
Frequently Asked Questions

A One Rep Max (1RM) is the maximum amount of weight you can lift for exactly one complete repetition of an exercise with proper form. It's the gold standard for measuring maximal strength and is widely used in strength training, powerlifting, and weightlifting to track progress and design training programs. Rather than testing your true 1RM (which can be risky), this calculator uses scientifically validated formulas to estimate it based on your performance at higher rep ranges.

No single formula is universally superior. The Epley formula (1RM = weight × (1 + reps/30)) is the most widely used and performs well for most lifters in the 1–10 rep range. The Brzycki formula tends to be more conservative at lower reps, while Lombardi may be more accurate at higher reps. Our calculator averages six formulas—Epley, Brzycki, Lombardi, Mayhew, O'Conner, and Wathan—to provide a balanced estimate. Research suggests that averaging multiple formulas reduces bias compared to relying on any single one.

Testing your true 1RM carries inherent risks, including acute injury and excessive fatigue, especially for inexperienced lifters. Maximal attempts require flawless technique, proper warm-up, and ideally the presence of a spotter. For most trainees, estimating 1RM from a set of 3–8 reps (using a calculator like this one) is safer and nearly as informative. If you do test your 1RM, ensure you follow a proper protocol: gradual warm-up sets, small incremental jumps, and adequate rest between attempts.

Once you know your estimated 1RM, you can program your training using percentage-based loading:
  • 90–100% 1RM — Developing maximal strength and neural adaptation (1–3 reps per set)
  • 80–90% 1RM — Building strength with moderate volume (3–6 reps)
  • 70–80% 1RM — Hypertrophy and strength endurance (6–12 reps)
  • 60–70% 1RM — Muscular endurance and recovery work (12–15 reps)
  • 50–60% 1RM — Active recovery, technique practice, and warm-up sets
Our percentage table updates automatically based on your calculated 1RM, giving you precise training weights for each intensity zone.

Strength levels can change noticeably within 4–8 weeks of consistent training. It's recommended to recalculate your 1RM every 4–6 weeks by performing a set to near-failure (leaving 1–2 reps in reserve) with a weight you can lift for 3–8 reps. Avoid testing too frequently—it can interfere with recovery and progress. Use the same exercise and rep range each time for consistent comparisons. Track your estimated 1RM over time to monitor strength gains objectively.

Yes, this 1RM calculator works for any resistance exercise—barbell squats, deadlifts, bench press, overhead press, rows, curls, and even machine exercises. The formulas are based on the relationship between load and maximum repetitions, which is fairly consistent across different movements. However, accuracy may vary slightly between compound lifts (which recruit more muscle mass) and isolation exercises. For the best results, use a weight you lifted with proper form to genuine near-failure (not just stopping at an arbitrary rep count).

Each formula was developed using different research populations and statistical models. Epley was derived from collegiate athletes, Brzycki from a broad fitness population, and Lombardi from powerlifters. Factors like training experience, muscle fiber composition, and exercise type all affect the load-reps relationship. The variation between formulas (usually within 3–7%) reflects this real-world variability. That's why we present the average—it smooths out individual formula biases and provides a more robust estimate for the general population.
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