How to Calculate Your One‑Rep Max (1RM)

Your “one‑rep max” (1RM) is the maximum weight you can lift for one repetition of an exercise. Accurately knowing your 1RM helps you plan your training intensity, track progress, and train safely.

The Landers Formula (Used by Our Calculator)

Our 1RM Calculator uses the Landers formula, a trusted method published in the NSCA Journal (1985):

1RM = (100 × Weight Lifted) / (101.3 − 2.67123 × Reps)

This formula gives a reliable estimate without requiring a true max lift.

How to Estimate Your 1RM

1. Choose a compound exercise (e.g., squat, bench press, deadlift).
2. Warm up properly (e.g., 50% of your estimated working weight for 8–10 reps).
3. Perform a challenging but safe set (e.g., 3–8 reps) with good form.
4. Record the weight you lifted and number of reps.
5. Enter those numbers into our free 1RM Calculator to get your estimated 1RM and training percentages.

What to Do with Your 1RM

• 55%–65% — endurance and form practice
• 70%–80% — hypertrophy / muscle growth
• 85%–95% — strength focus

For example, if your estimated 1RM is 100 kg, 70% is 70 kg — great for sets of 8–12 reps.

Safety Tips When Testing 1RM

• Always warm up thoroughly
• Use a spotter, especially when lifting heavy
• Reassess your 1RM every 4–8 weeks — avoid testing more often to prevent overtraining

Related Articles

• Your Guide to Calculating 1RM as a Beginner: Lift Smarter, Not Harder — step‑by‑step intro and safety advice
• Calorie Calculator — plan your nutrition to support strength goals
• Macronutrient Calculator — break down your daily calories into macros that suit your training
• AI‑Powered Personalized Workout Plan — build workouts based on your estimated 1RM and goals

FAQ

What is a 1RM calculator and how does it work?

It estimates your one-rep max based on the weight and reps you lifted using scientifically validated formulas like Landers, Epley, or Brzycki.

How often should I re-test my 1RM?

Around every 4–8 weeks is ideal — testing too often can lead to fatigue and injury.

Is testing my real 1RM safe?

It's safer to estimate via calculator than to attempt a true max lift. If you do test, always use a spotter.

Can I use the 1RM calculator for bodyweight exercises?

Yes — just enter your bodyweight as the “weight lifted” and number of reps

Ready to lift smarter? Calculate your 1RM now and take the guesswork out of your strength training.