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Use this free 1RM calculator to estimate the maximum weight you can lift for a single repetition. Enter the weight and number of repetitions you completed, and get instant results from five proven one rep max formulas.
1RM = One Rep Max
The maximum weight you can lift once with good form
Best with 3-6 reps
Formulas are most accurate in this rep range
5 proven formulas
Brzycki, Epley, Lander, Lombardi, O'Conner
Your one rep max (1RM) is the maximum weight you can lift for a single repetition with proper technique. It is the gold standard for measuring absolute strength. Coaches, athletes, and personal trainers use the one repetition maximum to design training programs, track progress, and compare strength levels across individuals.
Testing your actual 1RM requires lifting the heaviest weight you can manage for one complete rep. This can be risky, especially for beginners. A 1RM calculator provides a safer alternative. You lift a lighter weight for multiple reps, then the calculator uses a mathematical formula to estimate your maximum weight. The result is your estimated 1RM weight.
The concept is simple: there is a predictable relationship between the weight you lift and the number of repetitions you can perform. The heavier the weight, the fewer reps you can do. Researchers have studied this relationship for decades and developed several reliable formulas. Our 1RM calculator uses five of the most proven ones to give you a well-rounded estimate.
Follow these steps to get the most accurate estimate of your one rep max. The key is using good form and choosing the right weight and number of repetitions.
Do 2-3 warm-up sets with lighter weight. This reduces injury risk and prepares your muscles for heavier loads.
Pick a weight you can lift for 3 to 6 reps with good form. This rep range gives the most accurate results.
Lift until you can only do 1-2 more reps with proper technique. Count every full rep you complete.
Type the weight lifted and the number of repetitions into the calculator above. Select lbs or kg.
The calculator shows five formula results plus an average. Use the percentage chart to plan your training weights.
Each formula takes the same two inputs — the weight you lifted and the number of repetitions — but applies a different mathematical model. Here are the five formulas this 1RM calculator uses, along with a worked example for each. We will use 185 lbs for 5 reps.
Formula: 1RM = Weight × (36 / (37 − Reps))
Example: 185 × (36 / (37 − 5)) = 185 × (36 / 32) = 185 × 1.125
Result: 208.1 lbs
Developed by Matt Brzycki in 1993. Most accurate for 1-6 reps.
Formula: 1RM = Weight × (1 + Reps / 30)
Example: 185 × (1 + 5 / 30) = 185 × 1.1667
Result: 215.8 lbs
One of the oldest and most validated formulas. Works well across rep ranges.
Formula: 1RM = (100 × Weight) / (101.3 − 2.67123 × Reps)
Example: (100 × 185) / (101.3 − 13.356) = 18500 / 87.944
Result: 210.4 lbs
Developed by Lander. Provides results between Brzycki and Epley.
Formula: 1RM = Weight × Reps0.10
Example: 185 × 50.10 = 185 × 1.1746
Result: 217.3 lbs
Uses an exponential model. Tends to give slightly higher estimates.
Formula: 1RM = Weight × (1 + Reps / 40)
Example: 185 × (1 + 5 / 40) = 185 × 1.125
Result: 208.1 lbs
A more conservative formula. Gives lower estimates, especially at higher reps.
Brzycki: 208.1 | Epley: 215.8 | Lander: 210.4 | Lombardi: 217.3 | O'Conner: 208.1
Average estimated 1RM: 211.9 lbs
Once you know your estimated 1RM, you can use a percentage of your 1RM to program your workouts. Different percentages target different strength goals. This chart shows the relationship between percentage, reps, and training effect.
| % of 1RM | Reps | Training Goal | Example (1RM = 300 lbs) |
|---|---|---|---|
| 100% | 1 | Max Strength Testing | 300 lbs |
| 95% | 2 | Peak Strength / Peaking | 285 lbs |
| 90% | 3-4 | Maximal Strength | 270 lbs |
| 85% | 5-6 | Strength & Power | 255 lbs |
| 80% | 7-8 | Strength / Hypertrophy | 240 lbs |
| 75% | 9-10 | Hypertrophy | 225 lbs |
| 70% | 11-12 | Hypertrophy / Endurance | 210 lbs |
| 65% | 13-15 | Muscular Endurance | 195 lbs |
| 60% | 16-18 | Endurance / Warm-up | 180 lbs |
| 55% | 19-22 | Light Endurance | 165 lbs |
| 50% | 23+ | Recovery / Warm-up | 150 lbs |
Reps are approximate. Individual variation depends on muscle fiber type, training experience, and exercise selection.
Knowing your 1RM weight is the starting point for effective strength training programming. Here is how to use it to set and reach your strength goals.
If you are new to lifting, focus on training at 60-75% of your 1RM for sets of 8-12 reps. This builds a solid strength base while you learn proper technique. Re-test every 4 weeks. A realistic target is increasing your 1RM by 5-10% per month on compound lifts.
Once you have 6-12 months of training, use periodization. Alternate between strength phases (80-90% of your 1RM, 3-5 reps) and hypertrophy phases (65-80%, 6-12 reps). This keeps progress steady and prevents plateaus.
Advanced lifters should use percentage-based programs like 5/3/1 or Westside Conjugate. These programs systematically vary the percentage of your 1RM each week, building toward new PRs over 4-12 week cycles.
Log your workouts and recalculate your 1RM every 4-8 weeks. Compare your 1RM weight over time to see if your training is working. If progress stalls, adjust volume, intensity, or recovery.
Whether you are estimating your 1RM or testing it directly, proper technique and good form are essential. Follow these tips to stay safe and get accurate results.
Start with 5-10 minutes of light cardio, then do 2-3 progressively heavier warm-up sets before your working set. Cold muscles are more prone to injury.
Only count reps done with proper technique. If your form breaks down, stop the set. Sloppy reps give inaccurate estimates and increase injury risk.
Always have a spotter when lifting near your maximum weight, especially for bench press and squat. Safety pins or a power rack are also important.
For most lifters, using a 1RM calculator is safer than attempting a true one-rep max. You get a reliable estimate without the risk of lifting at absolute maximum weight.
Wait 3-5 minutes between heavy sets when testing or estimating your 1RM. Fatigue from previous sets will lower your number of repetitions and skew the estimate.
Avoid testing if you are injured, fatigued, sleep-deprived, or new to an exercise. Build a base of strength with moderate weights first.
These tables show approximate 1RM standards as a multiple of body weight for the three main compound lifts. Use them as a general guide to assess your strength level. Standards vary by age, sex, and body weight.
| Lift | Beginner | Intermediate | Advanced | Elite |
|---|---|---|---|---|
| Bench Press | 0.50x | 1.00x | 1.50x | 2.00x |
| Squat | 0.75x | 1.25x | 1.75x | 2.50x |
| Deadlift | 1.00x | 1.50x | 2.00x | 3.00x |
| Overhead Press | 0.35x | 0.65x | 1.00x | 1.40x |
| Barbell Row | 0.50x | 0.85x | 1.20x | 1.60x |
| Lift | Beginner | Intermediate | Advanced | Elite |
|---|---|---|---|---|
| Bench Press | 0.25x | 0.50x | 0.85x | 1.20x |
| Squat | 0.50x | 1.00x | 1.40x | 1.85x |
| Deadlift | 0.75x | 1.15x | 1.60x | 2.10x |
| Overhead Press | 0.20x | 0.40x | 0.65x | 0.90x |
| Barbell Row | 0.30x | 0.55x | 0.80x | 1.10x |
Standards are approximate. A 180 lb male with a 1.5x bench press would have a 1RM of 270 lbs. Individual results vary based on body composition, limb length, and training history.
A 1RM calculator is a tool that estimates your one repetition maximum — the maximum weight you can lift for a single rep with good form. Instead of testing to failure, you enter a lighter weight and the number of repetitions you completed, and the calculator uses proven formulas like Epley and Brzycki to predict your 1RM weight.
Most 1RM calculator formulas are accurate to within 5% when the number of repetitions is between 2 and 10. Accuracy decreases above 10 reps because the formulas were developed using lower rep ranges. For the most reliable estimate, use a weight you can lift for 3 to 5 reps with proper technique.
The Brzycki and Epley formulas are the most widely used and studied. Brzycki tends to be slightly more accurate for lower reps (2-6), while Epley works better for moderate reps (5-10). Our calculator shows all five formulas plus an average so you can compare results and choose the most conservative estimate.
Once you know your 1RM weight, use percentage-based training. For maximum strength, train at 85-95% of your 1RM for 1-5 reps. For muscle growth (hypertrophy), train at 65-80% for 6-12 reps. For muscular endurance, train at 50-65% for 15+ reps. Re-test or recalculate every 4-6 weeks to track progress toward your strength goals.
Testing a true 1RM carries more risk than estimating it. If you do test, always use a spotter, warm up thoroughly, and use proper technique and good form throughout the lift. For most recreational lifters, a 1RM calculator provides a safe and accurate enough estimate without the injury risk of maximal attempts.
Percentage of your 1RM refers to a fraction of your estimated maximum weight for one rep. For example, if your 1RM is 200 lbs, then 80% of your 1RM is 160 lbs. Coaches and training programs use these percentages to prescribe the right weight for different strength goals — heavier percentages for strength, lighter for endurance.
Enter a weight you can lift for 3 to 6 reps with good form. This range gives the most accurate 1RM estimate across all formulas. Above 10 reps, fatigue and cardiovascular factors influence results more than pure strength, making the number of repetitions less reliable for prediction.
Each formula was developed from different research populations and uses a different mathematical model. Brzycki uses a linear model, Epley uses a simple ratio, and Lombardi uses an exponential approach. The differences are usually small (within 5%), but they grow larger as the number of repetitions increases.
Yes, a 1RM calculator works for any barbell or dumbbell exercise — bench press, squat, deadlift, overhead press, rows, and more. The formulas are most accurate for compound lifts. For isolation exercises like bicep curls, the estimates may be less precise due to the smaller muscles involved.
Recalculate your 1RM every 4 to 8 weeks, or whenever your training performance changes noticeably. If you are completing your prescribed number of repetitions more easily than before, your 1RM has likely increased. Regular recalculation helps you adjust your training weights to keep making progress toward your strength goals.
Standards vary by body weight and experience. A beginner male might bench press 0.5x body weight, an intermediate lifter 1.0x, an advanced lifter 1.5x, and an elite lifter 2.0x or more. For women, multiply these numbers by roughly 0.6. These are general guidelines — your 1RM weight depends on training history, genetics, and body composition.
Disclaimer
This 1RM calculator provides estimates based on mathematical formulas and is intended for informational purposes only. It is not a substitute for professional coaching or medical advice. Always consult a qualified fitness professional before beginning a new exercise program. Use proper technique and good form when lifting weights. The authors are not responsible for any injuries resulting from the use of this tool.