One Rep Max Calculator

Your 1 rep max (1RM) is the maximum weight you can lift for one repetition - the peak weight you can handle for a single lift. Simply enter the weight you lifted and the reps completed, and we’ll calculate your estimated 1RM.

Units

Weight lifted

Reps performed

Estimated 1 Rep Max

Training Max (90%)

1 Rep Max by Formula

Popular one rep max estimation models by strength scientists and coaches.

Brzycki

Brzycki Formula

Popular linear model from submax testing; solid for moderate reps.

1RM = weight × 36 / (37 − reps)

O'Conner

O'Conner Formula

Similar to Epley but assumes ~2.5% per additional rep.

1RM = weight × (1 + 0.025 × reps)

Epley

Epley Formula

A widely used linear estimate, best for sets up to ~10 reps.

1RM = weight × (1 + reps / 30)

Lombardi

Lombardi Formula

Non-linear model where 1RM scales gently with reps^0.10.

1RM = weight × reps^0.10

Mayhew

Mayhew Formula

Regression model using exponential decay from athlete data.

1RM = 100 × weight / (52.2 + 41.9 × e^(−0.055 × reps))

RPE-Based Training Suggestions

See suggested loads for different RPEs based on your target reps.

Open the RPE Calculator

Chart reps

Warm-up Ladder

Warm-up sets leading into your top set. Uses lower RPEs to prepare without adding fatigue.

Disclaimer: Please note that this calculator provides estimates based on submaximal lifts and established formulas. Individual results may vary based on factors like technique, fatigue, and exercise selection. Always consult a professional and prioritize safety and proper form when testing your limits.

One Rep Max FAQ

Answers to common questions about estimating and using your one rep max.

Your one-repetition maximum is the most weight you can lift once with proper form for a given exercise. It’s commonly used to set training percentages for strength, hypertrophy, and power.

A Training Max is 90% of your estimated 1RM. Many programs use it to set sustainable percentages and drive consistent progress without overshooting.

1 rep max estimates are most reliable when sets are 10 reps or fewer and taken close to technical failure. Different formulas can vary, comparing a few methods (like Epley, Brzycki, Lombardi) or averaging results helps balance bias.

To calculate your 1RM without maxing out, use a hard submax set (3–10 reps) and estimate with common formulas like Epley or Brzycki. Many lifters compare or average formulas for a balanced estimate.

1RM is your true tested max. e1RM (estimated 1RM) is calculated from a formula. e1RM changes daily with fatigue, sleep, and performance.

To get an accurate estimate, use a submaximal set of 3–10 reps close to failure. The more reps you do, the less accurate the estimate becomes. Five‑rep estimates are often reliable when the set is near failure. Expect some margin of error based on experience level, exercise selection, and technique consistency.

There is no single best formula for estimating 1RM for everyone. Epley and Brzycki work well for moderate reps, Lombardi is non-linear, Mayhew comes from regression data. Averaging multiple formulas reduces bias.

Cutting or bulking does affect your 1RM. In a calorie deficit, 1RM can dip, in a surplus, it often improves. Sleep, stress, and recovery also impact e1RM day to day.

To warm up for your 1RM, do a general warm‑up, then ramp single sets: ~40–60% x 5, 70% x 3, 80% x 1–2, 85–90% x 1, then attempt. Avoid excessive fatigue before the top single rep.

Strength: ~80–92.5% 1RM for 1–6 reps. Hypertrophy: ~60–75% for 6–15 reps. Power: ~60–80% moved fast with intent. Adjust to your response.

1RM are slightly different for bench press, squat, and deadlift. Leverages and fatigue patterns differ by lift, so rep‑to‑percent relationships vary.

You can estimate 1RM from 2RM or 3RM. As rough guides: 2RM ≈ 95–97% of 1RM; 3RM ≈ 92–95%. Actual values vary by lift and lifter.

1RM for machines and free weights differ because machines change the strength curve and stabilization demands, so estimated 1RM won’t match free‑weight values one‑to‑one.

Brzycki’s formula estimates 1RM as weight × 36 / (37 − reps). It’s a linear model that works well for moderate reps.

O’Conner’s formula estimates 1RM as weight × (1 + 0.025 × reps). It’s similar to Epley but assumes ~2.5% per additional rep.

Epley estimates 1RM as weight × (1 + reps / 30). It’s widely used for moderate rep ranges.

Lombardi’s formula estimates 1RM as weight × reps^0.10. It’s a non-linear model that scales gently with reps.

Mayhew estimates 1RM as 100 × weight / (52.2 + 41.9 × e^(−0.055 × reps)), derived from regression on athlete data.