One-rep max calculator
Estimate the heaviest weight you could lift once (1RM) from a set you already did, without testing a true max, and get your training weights.
Quick answer
Your one-rep max (1RM) is the most you can lift for one rep. You can estimate it from any set of 2 to 12 reps: for example, 80 kg for 8 reps is a 1RM of about 100 kg.
Fill in the form to see your result.
Your estimated 1RM
| Reps | % of 1RM | Weight |
|---|
How it works
The formulas
The average of two classic estimates: Epley, weight × (1 + reps / 30), and Brzycki, weight × 36 / (37 − reps).
Best accuracy
Estimates are most reliable from sets of 3 to 8 reps taken close to failure, with good form.
The table
The usual percentage of 1RM you can lift for 1 to 12 reps, rounded to 2.5 kg or 5 lb.
FAQ
Should I test my real 1RM?
Not as a beginner. An estimate from a set of 3 to 8 reps is safer and accurate enough to plan your training.
Does it work for every exercise?
It works best for big lifts like the bench press, squat, deadlift and overhead press, less well for small isolation moves.
How often should I update it?
Every 4 to 6 weeks, or whenever your sets feel clearly easier. Kaizo updates your estimated 1RM after every workout.
General information, not medical advice. If you are pregnant, under 18 or have a medical condition, ask a health professional.
Other tools
Your records, updated live
Kaizo's gym mode logs your sets, estimates your 1RM after each workout and suggests the next weight.
