Enter the weight and clean reps from a hard set. Get an estimated 1RM, the range across three common formulas, and useful percentage loads without attempting a maximal lift.
Estimate Your One-Rep Max in Kg or Lb
A one rep max calculator estimates the heaviest weight you could lift once for the same exercise. It is useful for tracking strength and setting percentage-based gym loads when a true maximal test would add fatigue or risk for very little benefit.
This free tool works for any resistance exercise — squat, bench, deadlift or an accessory lift. It averages three established equations instead of pretending one formula is exact. The underlying research validated these equations on bench press and leg press specifically, so treat estimates for other lifts as a useful guide rather than a lab-tested number. Use a recent set performed with consistent technique, full range of motion and no more than 10 reps.
Your Lifting Set
Percentage-Based Training Loads
| Percentage | Estimated load |
|---|
Round to plates you can load. These numbers estimate capacity, not a training programme.
How to Use This Calculator
Choose a hard, recent set on the lift you want to estimate. Enter the total weight, including the bar, then enter how many clean reps you completed. Use the same unit you use in the gym. Press calculate to see the average estimate, formula range and loads from 50% to 95%.
For a more useful result, use a set of five reps rather than 10 where practical. Research comparing repetition-based predictions found lower-repetition tests more accurate than 10- or 20-rep tests. Stop if technique breaks down. A forced rep is not the same as a clean rep.
How One-Rep-Max Estimates Work
The Epley, Brzycki and Lombardi equations convert a submaximal set into a predicted maximum. They make different assumptions about how strength falls as reps rise, so their answers differ. This page shows the spread rather than hiding it.
Your real result depends on the exercise, fatigue, training experience and how close the set was to failure. Compare like with like over time. Use the same lift, setup and rep standard. Pair the result with the free training split recommender, or use the TDEE calculator for nutrition planning.
Method and source: the calculator uses Epley: weight × (1 + reps ÷ 30), Brzycki: weight ÷ (1.0278 − 0.0278 × reps), and Lombardi: weight × reps0.1. See Reynolds, Gordon and Robergs, Journal of Strength and Conditioning Research (2006), on predicting 1RM from multiple-repetition tests.
Your 1RM is the heaviest load you can lift once with sound technique for a specific exercise.
It is an estimate. Exercise choice, technique, fatigue and how close the set was to failure all affect the result. Predictions are generally more useful from lower-rep sets, and consistent technique tends to give better comparisons over time.
It shows the average of the Epley, Brzycki and Lombardi equations, plus each formula separately so you can see the prediction range. No single formula wins for every person and lift, which is why the tool shows three and averages them.
Yes. Choose kilograms or pounds before calculating. The percentage table stays in the unit you entered, so no conversion is needed.
You do not need to. A hard submaximal set gives a useful estimate without attempting a maximal lift. If you choose to test a true maximum, use appropriate experience, technique and safety equipment.