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Your one-rep max

Estimate your 1RM from the weight lifted and reps.

lb
reps
For the most accurate result, enter a set of 1–10 reps done with good form.
Estimated one-rep max
151.6 lb
Epley & Brzycki average
Training loads by percentage
100%
≈ 1 reps
151.6 lb
95%
≈ 2 reps
144.0 lb
90%
≈ 4 reps
136.4 lb
85%
≈ 6 reps
128.8 lb
80%
≈ 8 reps
121.3 lb
75%
≈ 10 reps
113.7 lb
70%
≈ 12 reps
106.1 lb

What is 1RM?

1RM (one-rep max) is the maximum weight you can lift just once with good form. It is a common way to measure your strength level and set training loads.

Because attempting a true max carries injury risk, it is usually estimated with a formula from the number of reps done with a lighter weight. Calxin uses the average of the Epley and Brzycki formulas.

The resulting 1RM is used to set training loads: high percentages for strength, lower percentages for endurance. For the most accurate result, enter a set of 1–10 reps.

How is it calculated?

1RM is estimated with a formula from the number of reps done with a lighter weight. The two most common formulas are Epley and Brzycki:

The two formulas:

Epley1RM = weight × (1 + reps / 30)
Brzycki1RM = weight × 36 / (37 − reps)

Calxin takes the average of these two. For example, 60 kg for 5 reps: Epley 70 kg, Brzycki 67.5 kg → average ≈ 68.8 kg.

Percentages of your 1RM correspond to different training goals:

Strength (low reps)90–100%
Muscle growth (medium reps)70–85%
Endurance (high reps)60–70%

For the most accurate result, enter a set of 1–10 reps done with good form; the estimate's error grows as reps increase. The calculated 1RM is a theoretical value; attempt maximal lifts with safety equipment and, when needed, a spotter.