● Strength & training

Your One Rep Max from any set.

Estimate your 1RM from a submaximal lift using 5 validated formulas — no need to max out. Get an intensity table and a comparison chart to plan every training block.

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1RM — One Rep Max Estimator

5 formulas · percentage table · bar chart comparison

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Your lift

Units

Weight lifted

Reps performed — between 1 and 10

reps

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Estimated 1RM

Average of 5 formulas

— lb

Epley

— lb

Brzycki

— lb

Lander

— lb

Lombardi

— lb

O'Conner

— lb

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Formula comparison

Enter your lift above to see the chart.

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Intensity table (% of 1RM)

%	Goal	Weight (lb)
Enter your lift above.

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How it's calculated

Five formulas, one average — how 1RM is estimated

The 1RM (One Rep Max) calculator estimates the maximum weight you could lift for a single repetition from any submaximal set of 1–10 reps. For example, if you bench press 185 lb for 5 reps, the Epley formula estimates a 1RM of approximately 208 lb, while Brzycki gives about 214 lb. Using the average of all five formulas reduces the error of any individual equation.

Each formula takes the weight lifted (w) and the number of repetitions (r) and projects the theoretical maximum. All formulas become less accurate above 10 reps — keep your test set in the 3–8 rep range for best results.

Epley: w × (1 + r / 30)
Brzycki: w × 36 / (37 − r)
Lander: 100 × w / (101.3 − 2.67123 × r)
Lombardi: w × r^0.10
O'Conner: w × (1 + 0.025 × r)

1
Epley — linear projection
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2
Brzycki — asymptotic model
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3
Lander — regression-based
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4
Lombardi — power model
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5
O'Conner — conservative estimate
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6
Average of all five formulas
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Understand the terms

1RM (One Rep Max): The maximum weight you can lift for exactly one repetition with correct form. The gold standard for measuring absolute strength.
Hypertrophy: Muscular growth triggered by mechanical tension, metabolic stress and muscle damage. Typically trained at 65–80% 1RM for 8–15 reps per set.
Neuromuscular adaptation: Improvements in strength that result from better motor unit recruitment and firing rate, rather than from increased muscle size. Dominant in the early weeks of training.
Progressive overload: The principle of gradually increasing the demands on the musculoskeletal system — usually by adding weight, reps or sets over time — to continue driving adaptation.

See the full glossary →

Disclaimer: estimation tool for informational and training-planning purposes. All 1RM formulas are mathematical models and may differ from your true maximum, particularly when rep counts exceed 10. Results do not replace proper coaching, individual assessment or supervised testing. Do not attempt true 1RM testing without adequate warm-up, a spotter or safety equipment.

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Frequently asked questions — 1RM

What is 1RM (One Rep Max)?

1RM is the maximum weight you can lift for exactly one repetition with correct technique. It is the standard benchmark for absolute strength in powerlifting, Olympic weightlifting and general strength training. You can measure it directly (with proper precautions) or estimate it from a submaximal set using formulas like the ones in this calculator.

Which 1RM formula is most accurate?

No single formula is universally superior. Research shows Brzycki and Epley tend to perform best for sets of 2–6 reps, while Lander is often cited for accuracy at higher rep ranges. Because accuracy varies by individual, exercise and fatigue level, this calculator shows all five formulas plus their average — which typically reduces the error of any single equation.

How do I safely test my 1RM?

1. Warm up with 5–10 minutes of light cardio and dynamic stretching. 2. Perform progressive warm-up sets (50%, 70%, 85%, 95% of expected 1RM). 3. Rest 3–5 minutes between attempts. 4. Increase weight by 2–5% each attempt. 5. Always use a spotter or safety racks. Stop immediately if form breaks down. Alternatively, estimate your 1RM from a set of 3–8 reps using this calculator — it is safer and accurate enough for programming.

How often should I max out?

Competitive powerlifters may max out every 6–8 weeks in training, plus at meets. For recreational and intermediate lifters, a true 1RM test every 8–12 weeks is sufficient. Over-testing is fatiguing and carries injury risk. Using this calculator to estimate 1RM from submaximal sets weekly is a safer alternative that gives ongoing tracking without the stress of true maximal efforts.

How do I use 1RM in training programming?

Training loads are prescribed as percentages of your 1RM: 50–60% for technique and warm-up work; 65–75% for hypertrophy (8–12 reps); 75–85% for strength (4–8 reps); 85–95% for maximal strength (1–4 reps); 95–100% for peaking and competition preparation. The intensity table in this calculator automatically calculates the weight at each zone so you can load the bar precisely.

📚 Learn more — official sources

🔬 Study Brzycki (1993) — Strength testing: predicting a one-rep max from reps-to-fatigue Original paper proposing the Brzycki formula, one of the most widely used 1RM prediction equations in strength and conditioning research. See on PubMed → 🏛️ Organization NSCA — Testing for Maximal Strength National Strength and Conditioning Association guide on safe 1RM testing protocols, including warm-up procedures and recommended rest intervals. See official source → 🔬 Study Schoenfeld (2010) — Mechanisms of muscle hypertrophy and their application to resistance training Foundational review on how progressive overload drives hypertrophy, directly informing how 1RM percentages are applied in programming for size and strength. See on PubMed → 🏛️ Organization ACSM — Resistance Training Position Stand American College of Sports Medicine position stand on resistance training, including evidence-based guidelines for load prescription using 1RM percentages. See official source →

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About the 1RM Calculator

The One Rep Max (1RM) is the cornerstone of strength programming. Knowing your 1RM allows you to train at precise intensity zones — whether your goal is hypertrophy, strength, or peaking for competition. Direct 1RM testing requires careful preparation and carries a higher injury risk; this calculator lets you estimate it safely from any set of 1–10 reps you perform during a normal training session.

Five widely cited prediction formulas (Epley, Brzycki, Lander, Lombardi and O'Conner) are computed simultaneously and averaged to reduce individual formula error. The resulting percentage table maps your estimated 1RM to eight intensity zones, so you can walk into the gym knowing exactly what to load on the bar.