One-rep max calculator
What you could lift once, from the weight and reps of a set, without testing a max. Plus a table of working weights.
Track it every day in the app
Gloox remembers every set and suggests today's weight: it looks at what you did last time and proposes the next step up.
On a computer? Point your phone's camera here to get the app.
How 1RM is estimated
The calculator averages two formulas, Epley (weight × (1 + reps / 30)) and Brzycki (weight × 36 / (37 − reps)). Both are most accurate for sets of up to 10 reps: the more reps, the more endurance counts instead of strength.
Why know your one-rep max
Most programmes set weights as a percentage of 1RM: 80–90 % for strength, 65–80 % for size. Estimating it is safer than testing a max under the bar.
Questions
Does it work for dumbbells and machines?
Yes, the formula works for any exercise, but it is most reliable for the big barbell lifts: bench, squat and deadlift.
How often should I recalculate?
Every 4–6 weeks, or when your weight for the usual reps has clearly gone up.