Estimate your one-rep max for any lift based on a weight you can do for multiple reps. Uses three validated formulas.
Your one-rep max (1RM) is the maximum weight you can lift for a single repetition of a given exercise with proper form. It is the standard measure of strength and is used to prescribe training loads as percentages. For example, a program might call for 5 sets of 5 at 80% of your 1RM. Rather than testing your actual 1RM (which carries injury risk), this calculator estimates it from a submaximal lift using established prediction formulas.
Enter the weight you lifted and the number of repetitions completed (up to 10 reps for best accuracy). The calculator estimates your 1RM using the Epley, Brzycki, and Lombardi formulas and shows the average. It also generates a percentage chart showing target weights for common training rep ranges (1-12 reps).
Strength (1-5 reps): Train at 85-100% of 1RM. Hypertrophy (6-12 reps): Train at 65-85% of 1RM. Endurance (12+ reps): Train at 50-65% of 1RM. These ranges are guidelines; individual response varies. For most recreational lifters, training in the 70-85% range (5-10 reps) provides the best combination of strength and muscle growth.
Your one-rep max (1RM) is the maximum weight you can lift for a single repetition with proper form. Direct 1RM testing carries injury risk, so most lifters and coaches estimate it using submaximal formulas. The Epley formula (1RM = weight x (1 + reps/30)) and Brzycki formula (1RM = weight x (36 / (37 - reps))) are the most widely used. These formulas are most accurate with rep ranges of 2-10; accuracy decreases significantly above 10 reps because muscular endurance becomes a confounding factor.
Training intensity is commonly prescribed as a percentage of 1RM. Strength training typically uses 80-95% of 1RM for 1-5 reps. Hypertrophy (muscle growth) training uses 65-80% for 6-12 reps. Muscular endurance training uses 50-65% for 15+ reps. The National Strength and Conditioning Association (NSCA) recommends retesting estimated 1RM every 4-8 weeks as strength changes, since training percentages based on an outdated 1RM will not provide optimal stimulus.
Common strength benchmarks for intermediate male lifters (1-3 years of consistent training): bench press 1.0-1.5x bodyweight, squat 1.5-2.0x bodyweight, deadlift 1.5-2.5x bodyweight, overhead press 0.65-1.0x bodyweight. Female benchmarks are typically 60-70% of male benchmarks relative to bodyweight. These are general guidelines; genetics, body proportions, training history, and age all affect individual strength potential. The Pace Calculator serves a similar benchmarking purpose for runners.
Progressive overload, the gradual increase of training stress over time, is the fundamental driver of strength gains. Tracking your estimated 1RM over months and years provides objective evidence of progress that subjective feelings cannot match. A training log comparing estimated 1RM at 4-week intervals helps identify plateaus early so programming adjustments can be made. Common plateau-breaking strategies include deload weeks (reducing volume and intensity by 40-60% for one week), varying rep ranges, changing exercise variations, and addressing technique inefficiencies. Recovery factors including sleep quality, nutrition, and stress management are equally important because strength adaptations occur during recovery, not during the training session itself.