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Your one-rep max

Estimate your 1RM from the weight lifted and reps.

kg
reps
For the most accurate result, enter a set of 1–10 reps done with good form.
Estimated one-rep max
68.8 kg
Epley & Brzycki average
Training loads by percentage
100%
≈ 1 reps
68.8 kg
95%
≈ 2 reps
65.3 kg
90%
≈ 4 reps
61.9 kg
85%
≈ 6 reps
58.4 kg
80%
≈ 8 reps
55.0 kg
75%
≈ 10 reps
51.6 kg
70%
≈ 12 reps
48.1 kg
Info

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.

Method

How Is 1RM 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:

Epley: 1RM = weight × (1 + reps / 30)
Brzycki: 1RM = 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:

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

For the most accurate result, enter a set of 1–10 reps done with good form; the estimate's error grows as reps increase.