Estimate your one-rep max and training weights based on your most recent set — safe, smart, simple and free.
Your 1-RM is: —
This One-Rep Max (1RM) Calculator helps you estimate the maximum amount of weight you can lift for a single repetition of any given exercise — based on how much weight you used and how many reps you completed.
It uses the Landers Formula, introduced in 1985 in the NSCA Journal, a trusted and widely accepted method in strength training science. The formula is:
1RM = (100 × Weight Lifted) / (101.3 − 2.67123 × Reps)
Here’s how it works:
Important Safety Reminder:
Never test your one-rep max without supervision. Attempting a true 1RM lift without a spotter can be extremely dangerous. If you're going to push to failure, always train with a partner — ideally, one on each side of the bar.
Whether you're programming your next strength phase or simply curious about your potential, this tool gives you a smart and practical way to personalize your workouts — all based on what you're already doing in the gym.
Scientific Reference:
Landers J. Maximum based on reps. NSCA Journal, 1985.
A 1RM calculator (also called 1RM calc, one rep max calculator, or rep max calculator) is a tool to estimate your one rep max (1RM) for any exercise. Just enter the weight lifted and the number of reps, and the calculator will determine your estimated 1RM using proven formulas like Epley or Brzycki. Use this 1RM calculator to calculate, estimate, or determine your 1RM quickly and safely.
Common mistakes include using poor form, guessing your rep count, or inputting a set done to complete failure. For best results, use good technique and record your true reps and weight.
The calculator can estimate max reps for bodyweight moves (like push-ups or pull-ups) if you know your max effort set. Just enter your body weight as the “weight lifted.”
For most people, checking your estimated 1RM every 4–8 weeks is ideal. Too frequent testing can lead to fatigue, while regular check-ins help track progress safely.
Our calculator uses scientifically validated formulas to estimate your 1RM based on the weight you lifted and the number of reps performed. Just enter your numbers and see your estimated max.
By default, we use the Epley formula, which is widely recognized for its accuracy:
1RM = weight × (1 + reps / 30)
Other formulas may be used for different rep ranges. You can learn more about them in the article below the calculator.
Directly testing your true 1RM can be risky, especially for beginners. Using a calculator is a safer way to estimate your max without pushing to absolute failure.
You can use this calculator for major lifts like bench press, squat, deadlift, overhead press, and more—basically any compound lift or isolation exercise where you know the reps and weight.
The 1RM formulas give a solid estimate for most lifters, especially for sets of 3–10 reps. Results can vary based on experience, fatigue, and exercise type.
Knowing your 1RM helps you set training weights for various rep ranges (like 60% for endurance, 80% for strength). You’ll find a chart below to guide you.
Absolutely! Beginners should estimate their 1RM from submaximal sets (e.g., a set of 5–8 reps) rather than testing their max directly. This is much safer and still useful.
No registration or payment is required. The 1RM calculator is free for everyone to use.