One-Rep Max Calculator

Estimate your 1RM from a set, with a % loading table.

Peso (kg)

Repeticiones

Más preciso con 2-10 repeticiones cerca del fallo.

Estimación · 1RM

114.6 kg

Epley: 116.7 kgBrzycki: 112.5 kg

Porcentaje del 1RM (según el promedio)

% 1RM	Carga (kg)	Repeticiones típicas
100%	115	1
95%	109	2
90%	103	4
85%	97	6
80%	92	8
75%	86	10
70%	80	12
65%	74	15

Revisado por el CalcFitLab Editorial TeamActualizado el 2026-08-01Leer nuestra metodología

Cómo funciona la one-rep max calculator

Your one-rep max (1RM) is the most weight you can lift for a single repetition. Testing a true 1RM is risky, so most lifters estimate it from a set taken close to failure.

This tool shows two published estimates. The Epley formula (1985) is 1RM = weight x (1 + reps/30). The Brzycki formula (1993) is 1RM = weight x 36 / (37 - reps). Both are accurate for sets up to about ten reps and diverge as rep counts climb.

The percentage table below turns your estimated 1RM into working loads. It follows the standard strength-training relationship where roughly 85% of 1RM allows about 6 reps and 75% allows about 10.

Estimates are most accurate at 2-10 reps. Above that, error grows quickly.
Epley and Brzycki agree closely at low reps and separate as reps rise. Use them as a range, not a single true value.
Round working weights to the nearest plate you actually have.

Preguntas frecuentes

Neither is universally better. They match closely at low reps; Epley tends to read slightly higher at high reps. Using both gives you a sensible range rather than a single point estimate.

Between 2 and 10 reps taken close to failure. Single-rep and very high-rep sets make the estimate less reliable.

Yes. A true 1RM attempt carries higher injury risk, especially without a spotter. Estimating from a moderate set avoids maximal loading while still guiding your training percentages.