One Rep Max Calculator
Calculate your one-repetition maximum using proven formulas. Get personalized training load recommendations and rep range charts for optimal strength development.
Ready to Calculate
Enter your lift details and click "Calculate 1RM" to get your estimated one-rep maximum and training recommendations.
1RM Calculator Guide
Your one-rep maximum (1RM) is the heaviest weight you can lift once with proper form. Use it to design training programs, track progress, and train at the right intensity for your goals.
Which Formula to Use
Brzycki: Best for 1-7 reps (most accurate for powerlifting)
Epley: Best for 8-15 reps (most commonly used)
O'Conner: Good middle ground for 5-10 reps
Lombardi: Conservative estimates (good for beginners)
Important: These are estimates that can vary ±5-10%. Calculate when fresh, use proper form, and test actual 1RMs progressively with spotters. Results are specific to each exercise.
Formula Comparison
Epley
1RM = W × (1 + R / 30)Best for higher rep ranges (8-15)
Brzycki
1RM = W / (1.0278 - 0.0278 × R)Best for lower rep ranges (1-7)
Lombardi
1RM = W × R^0.10Moderate accuracy across rep ranges
O'Conner
1RM = W × (1 + 0.025 × R)Best for moderate rep ranges (5-10)
Rep Range Chart
Want to track every 1RM automatically? See how Tracked's built-in calculators and personal record tracking work inside the app.
Frequently Asked Questions
Which 1RM formula should I use?
Use Brzycki for sets of 1-7 reps, Epley for 8-15 reps, and O'Conner as a middle-ground option for 5-10 reps. Lombardi gives a more conservative estimate.
How accurate are 1RM calculators?
Estimates typically fall within ±5-10% of your true 1RM. Accuracy decreases as rep count increases, so lower rep sets (1-10) give the most reliable predictions.
How do I use my 1RM for training?
Use the rep range chart to find the percentage of your 1RM for the rep range and training goal you're working toward — lower percentages for endurance, higher for strength and power.
Explore More Free Calculators
Keep dialing in your training and nutrition with our other free calculators.