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1RM Calculator

Enter the weight and reps from a recent hard set to estimate your one-rep max and useful training percentages.

Lift details

Estimate your max

Use a challenging set of 2–10 clean reps for the most useful estimate. RIR is saved as context and does not turn this formula estimate into a measured max. Avoid testing to failure without appropriate safety equipment or a qualified spotter.
Estimated one-rep max
Enter a completed set

Primary result uses the Epley formula. Estimates vary by exercise, technique, fatigue, and training experience.

Epley
—
Brzycki
—
Lombardi
—
Your training loads

Rounded from your Epley estimate to match the smallest practical loading step.

Enter a completed set to build your loading table.

Saved estimates stay in this browser only.
Scientific Strength Estimation

The mathematics behind one-rep max formulas

A hard submaximal set can provide a useful estimate without requiring a maximal attempt. It is still demanding, and the result can vary with the exercise, technique, fatigue, and the formula used.

Interpret the result as a range

Lower-repetition sets usually reduce the influence of muscular endurance, but no formula is universally accurate. Compare the three estimates and use the result to guide training rather than treating it as a measured maximum. Review the evidence.

Comparing the Major 1RM Formulas

Epley Formula (1985)1RM = Weight × (1 + Reps / 30)

A widely used linear estimate. It often produces a higher result as the repetition count rises, so compare it with the other formulas.

Brzycki Formula (1993)1RM = Weight × (36 / (37 - Reps))

A linear formula that is often slightly more conservative than Epley at higher repetition counts.

Lombardi Formula (1989)1RM = Weight × Reps^0.10

Uses an exponential curve rather than a linear relationship. Its estimate may sit above or below the other formulas depending on the completed set.

Target Adaptation Spectrum

How to train using 1RM percentages

Percentage ranges are practical starting points, not fixed adaptation zones. Exercise selection, effort, total sets, and training experience still matter.

90% – 100% 1RM

Maximal Strength

1 – 3 Reps · 3 – 5 min rest

Useful for practicing heavy, low-repetition strength work when technique and appropriate safety support are in place.

80% – 90% 1RM

Strength & Power

4 – 6 Reps · 2 – 3 min rest

A common range for strength-focused compound lifting, with enough rest to preserve repetition quality.

70% – 80% 1RM

Hypertrophy (Muscle Growth)

8 – 12 Reps · 60 – 90s rest

A common hypertrophy-oriented range, although muscle growth can occur across a broader range of loads when sets are sufficiently challenging.

50% – 70% 1RM

Endurance & Speed

12 – 20+ Reps · 30 – 60s rest

Often used for higher-repetition work, technique practice, or power exercises that intentionally use lighter loads.

Example submaximal testing ramp-up

This is one example for a familiar barbell lift, not a universal protocol. Adjust the number of warm-up sets and loads to the exercise and your experience.

Set 1
Empty Bar / 40%
10 reps

Joint lubrication & pattern groove

Set 2
55% estimated 1RM
5 reps

Moderate bar speed

Set 3
70% estimated 1RM
3 reps

Fast concentric drive

Set 4
82% estimated 1RM
1 rep

Neural potentiation (PAP)

Set 5 (Test)
87% estimated 1RM
3–5 reps (RPE 9.5)

Record load & reps in calculator

Frequently asked questions

1RM Calculator & Strength FAQs

Clear answers to common questions about calculating one-rep maxes, training percentages, and lift progression.

What is a one-rep max (1RM)?+

A one-rep max (1RM) is the maximum amount of weight a person can lift for a single repetition of a given exercise through a full range of motion with proper technique.

Why should I estimate my 1RM instead of testing a true single?+

A submaximal estimate can reduce the need for frequent maximal attempts and is convenient for planning percentage-based training. It is not risk-free and should be treated as an estimate rather than a guaranteed maximum.

Which 1RM formula is the most accurate?+

No single formula is best for every exercise and person. This calculator shows Epley, Brzycki, and Lombardi together so you can see the spread and use it as a practical estimate range.

How many reps should I perform to get an accurate 1RM estimate?+

Between 2 and 6 repetitions. Once you exceed 10 repetitions, physiological fatigue is heavily influenced by aerobic endurance and lactic acid tolerance rather than pure neuromuscular force production.

Does 1RM differ between barbells, dumbbells, and machines?+

Yes. Stability requirements, range of motion, machine leverage, and technique differ, so an estimate should only be compared with the same exercise and equipment setup.

How often should I recalculate my 1RM?+

Recalculating every 4 to 8 weeks—or at the end of each dedicated training block—is ideal. As you add reps or load to your standard working sets, update your 1RM to keep your percentage-based training calibrated.

Can I use this 1RM calculator for bodyweight movements like Pull-Ups or Dips?+

Yes! When calculating for weighted pull-ups or dips, enter your total system weight (your bodyweight plus the added external weight on your dip belt).

How should I structure my routine using these 1RM percentages?+

Use our free Workout Routine Builder to structure your exercises, assign precise percentages and rest periods, and generate a complete printable or mobile-ready training session.

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