One Rep Max (1RM) Calculator
Estimate your maximum lifting strength based on the weight and repetitions you perform. Use this tool to plan your strength, hypertrophy, or endurance training effectively.
How to Use This Calculator
Follow these simple steps to estimate your one-rep max without actually attempting a maximal lift:
- Enter the weight lifted -- input the amount of weight you successfully lifted for multiple repetitions. Use a weight that challenges you within the 2 to 10 rep range for the most accurate estimate.
- Enter the number of repetitions -- record how many complete reps you performed with good form. The calculator accepts values between 1 and 20, but estimates are most reliable with fewer than 10 reps.
- Select your exercise -- choose the lift you performed (bench press, squat, deadlift, overhead press, or barbell row) for context.
- Choose a formula -- select from Epley, Brzycki, Lander, or O'Conner formulas. Epley is the most widely used default.
- Review your results -- your estimated 1RM appears along with a percentage breakdown table and training zone recommendations for strength, power, hypertrophy, and endurance.
Understanding One Rep Max (1RM)
What Is a 1RM?
A one-repetition maximum (1RM) is the heaviest weight you can lift for a single complete repetition of a given exercise with proper form. It is the gold standard measurement of maximal strength and serves as the foundation for designing structured training programs. Knowing your 1RM allows you to calculate precise training loads for different goals, whether you are building pure strength, maximizing muscle growth, or improving muscular endurance.
Why Does 1RM Matter?
Strength coaches and athletes use the 1RM to prescribe training intensities as percentages of maximum effort. For example, hypertrophy training typically uses 65 to 85 percent of 1RM, while maximal strength work requires 85 to 100 percent. Without knowing your 1RM, programming training loads becomes guesswork. Estimating your 1RM from submaximal lifts is safer than attempting a true maximal lift, especially for beginners or those training without a spotter.
Common 1RM Estimation Formulas
Epley Formula (most popular)
1RM = weight x (1 + reps / 30)
Brzycki Formula
1RM = weight / (1.0278 - 0.0278 x reps)
Lander Formula
1RM = (100 x weight) / (101.3 - 2.67123 x reps)
O'Conner Formula
1RM = weight x (1 + 0.025 x reps)
All formulas produce similar results when reps are between 1 and 10. Accuracy decreases as rep counts increase beyond 10 because the relationship between submaximal weight and true 1RM becomes less linear at higher repetitions.
Safety Considerations
Always warm up thoroughly before lifting heavy. Use a spotter or safety pins when testing near-maximal loads. Avoid testing a true 1RM if you are new to strength training; instead, use this calculator with a comfortable 3 to 5 rep set. Never sacrifice form for heavier weight, and allow at least 48 hours of recovery before retesting.
Percentage of 1RM and Rep Ranges
This reference table shows the typical relationship between the percentage of your 1RM and the number of repetitions you can expect to perform at that load.
| % of 1RM | Expected Reps | Training Goal |
|---|---|---|
| 100% | 1 | Maximal Strength |
| 95% | 2 | Maximal Strength |
| 90% | 3 - 4 | Strength / Power |
| 85% | 5 - 6 | Strength |
| 80% | 7 - 8 | Strength / Hypertrophy |
| 75% | 8 - 10 | Hypertrophy |
| 70% | 10 - 12 | Hypertrophy |
| 65% | 12 - 15 | Endurance / Hypertrophy |
| 60% | 15 - 20 | Muscular Endurance |
| 50% | 20+ | Muscular Endurance |
Disclaimer
This calculator provides estimates based on established mathematical formulas and is intended for educational and training planning purposes only. Actual one-rep max strength varies between individuals due to factors such as training experience, muscle fiber composition, technique, fatigue, and nutrition. Never attempt a maximal lift without proper supervision and safety equipment. If you are new to strength training or have any health conditions, consult a qualified fitness professional or healthcare provider before testing your limits.
Strength Standards by Exercise and Bodyweight
How does your one-rep max stack up? The table below provides widely-cited strength standards for the four main barbell lifts — bench press, squat, deadlift, and overhead press — across training experience levels. Standards are expressed as a multiplier of bodyweight and apply to adult males. Female standards are typically 60–70% of the values shown.
| Exercise | Beginner | Intermediate | Advanced | Elite |
|---|---|---|---|---|
| Bench Press | 0.5× BW | 1.0× BW | 1.5× BW | 2.0× BW |
| Squat | 0.75× BW | 1.25× BW | 1.75× BW | 2.5× BW |
| Deadlift | 1.0× BW | 1.5× BW | 2.0× BW | 2.75× BW |
| Overhead Press | 0.35× BW | 0.65× BW | 1.0× BW | 1.3× BW |
| Barbell Row | 0.5× BW | 0.9× BW | 1.3× BW | 1.75× BW |
BW = bodyweight. Standards from Stronger By Science / ExRx.net research. Individual variation is significant.
How to Increase Your 1 Rep Max: Periodization Guide
Systematically building your 1RM requires structured programming — not just lifting heavy every session. Periodization is the planned variation of training intensity and volume over time to drive strength adaptations while managing fatigue and injury risk. Here are the three most effective periodization models for 1RM improvement.
Linear Periodization (Best for Beginners)
Increase weight each session while reps stay constant, or decrease reps as weight increases weekly. Simple and highly effective for newer lifters whose nervous system and muscle mass can adapt quickly.
Daily Undulating Periodization (DUP) — For Intermediate Lifters
Vary the rep range each session within the same week. Training strength, hypertrophy, and power on different days stimulates multiple adaptation pathways simultaneously and prevents stagnation.
Block Periodization (Advanced / Powerlifting)
Organize training into distinct blocks: accumulation (high volume, moderate intensity), intensification (moderate volume, high intensity), and realization (low volume, peak intensity / test week). Used by most competitive powerlifters.
General 1RM Improvement Timeline: Intermediate lifters typically add 2–5% to their 1RM per training block (6–12 weeks) with consistent programming. Advanced lifters may see only 1–2% improvement per block, which is why they use more sophisticated periodization strategies.
How to Safely Test Your Actual 1 Rep Max
While this calculator estimates your 1RM from submaximal reps, there are times when you want to test your actual maximum — after completing a training block, before a competition, or to update your training percentages. A proper 1RM testing protocol minimizes injury risk and ensures an accurate result.
- 1Choose the right day. Test when well-rested: at least 48 hours after your last heavy session. Avoid testing when sick, overly stressed, or sleep-deprived.
- 2Warm up thoroughly. Start with 2 sets of 10 at 40–50%, then 3 reps at 60%, 2 reps at 75%, 1 rep at 85%, and 1 rep at 90–95%. Rest 3–5 minutes between warm-up singles.
- 3Make conservative jumps. Increase by 2.5–5% increments. Attempting too large a jump risks failure or injury. If you make the lift comfortably, rest 5 minutes and go heavier. Stop after two consecutive failures.
- 4Use a spotter and safety equipment. Never attempt a true maximal squat or bench press without a spotter or safety bars. For deadlifts, ensure the platform is clear and you have chalk or straps if needed.
- 5Limit testing frequency. Test 1RM at most every 8–12 weeks. Frequent maximal testing is fatiguing and offers diminishing returns. Use submaximal estimation (like this calculator) between test days to track progress.
Training Age and Expected Rate of 1RM Progress
One of the most common questions among lifters is “how fast should my 1 rep max increase?” The honest answer depends heavily on training age — how long you have been lifting consistently with progressive overload. Beginners can make gains in weeks; advanced lifters may work months for a single kilogram improvement.
| Training Level | Expected Monthly Gain (Bench) | Expected Monthly Gain (Squat) | Key Focus |
|---|---|---|---|
| Beginner (0–1 yr) | 2–4 kg / 5–9 lbs | 3–6 kg / 7–13 lbs | Form, frequency, progressive overload |
| Intermediate (1–3 yr) | 1–2 kg / 2–4 lbs | 1.5–3 kg / 3–6 lbs | Structured periodization, volume |
| Advanced (3–5 yr) | 0.5–1 kg / 1–2 lbs | 0.75–1.5 kg / 2–3 lbs | Block programming, technique refinement |
| Elite (5+ yr) | 0.1–0.5 kg / 0.2–1 lb | 0.2–0.75 kg / 0.4–1.5 lbs | Competition peaking, minor gains |
Monthly gain estimates assume consistent training, adequate nutrition, and sleep. Individual variation is significant. Data based on published strength research guidelines.