One Rep Max Calculator

One rep max (1RM) refers to the max weight you can lift for one repetition in a given exercise. It is an important variable for gauging overall strength and thus helps chalk out an effective, personalized body building plan. 



In this post, we explain how you can use online tools like a one rep max 1RM calculator to determine your individual rep max. Additionally, we also highlight the practical applications of one rep max in resistance training.

What Is One Rep Max (1RM)?

One rep max is a measure of your strength and stamina for any given exercise.

Each workout is different in terms of exertion and stress, which is why your muscular strength varies for all exercises.

The maximum muscular strength for a particular weight lifting workout is determined by the maximum weight you can lift for just one repetition.

It is essential to mention that one rep max is often confused with the rate of perceived exertion or RPE. RPE is a rating you assign to an exercise based on how strenuous it feels. This rating can understandably fluctuate based on your mood and general health.

However, 1RM is an objective measure of your muscle strength for a particular exercise, and this value does not vary due to external factors.

For better understanding, let’s check how a one rep max is calculated manually:

  • Start lifting a weight you can comfortably do at least ten repetitions with.
  • After ten reps, rest until your heart rate and breathing is stable and you feel 100% recovered.
  • Gradually increase the load until you reach the one you can do three reps with. Again, take a rest until you completely recover.
  • Now, pick the heaviest weight that you can lift with the correct technique for one rep. This weight is your one rep max.

While the above-mentioned steps are one way to go about accurately estimating your one rep max, the method is strenuous and can be unsafe, especially for beginners.

This is where a one rep max calculator comes in.

On the calculator, instead of entering how much weight you are able to lift for a maximum of 1 repetition, you can enter any load (in kg or pounds) and the maximum amount of repetitions you are able to perform with it.

Based on the weight and its corresponding maximum repetitions, the calculator generates your one rep max.

Additionally, it also displays the percentage of muscle strength in relation to your maximum strength for different loads. This is called lifting percentage.

For example, if you’re able to lift 10 kg weight for two reps, your one rep max is 11 kg, according to the calculator. This implies that lifting 8 kg will require 80% of your max strength.

How To Maximize Accuracy On One Rep Max Calculator?

While one rep max calculators are widely used by trainers, as well as people practicing resistance exercise, they are not as accurate as manual methods of trying different weights.

Here are some ways you can maximize the accuracy of one rep max:

  • Instead of going for lighter loads and their respective max repetitions, it is preferable to enter lower numbers of reps (corresponding to heavier loads). In other words, a 3RM will give you a better estimate of 1RM than a 10RM.
  • Stop your set once your range of motion decreases.

While the above two steps won’t generate perfect 1RM on the calculator, the result will be reliable enough to be used for resistance exercise.

Application Of One Rep Max In Resistance Training

Each individual has different muscle memory, strength, and weakness. This is why, when you train for weight lifting or even in a general workout, a personalized approach central to your health and energy level is important.

Knowing the max weight you’re able to lift comes in handy in devising the most effective training plan for you. This ensures you achieve your fitness goals quickly with minimal risk of injuries. The muscle gain through a well throughout the plan is also sustainable.

Strength Training Exercise For Lean Body Weight

Lean body weight is your total body weight minus the fat mass. Fat percentage contributes to several metabolic syndromes, cardiovascular diseases, and general fatigue. Therefore, using resistance training exercises to get rid of body fat (and gain lean muscle mass) is good for health.

Here are some of the best weight lifting exercises you can incorporate into your training routine (considering their respective one rep max).

Bench Press

The bench press is one of the best resistance training exercises. They work on pectoralis major, deltoid (anterior), triceps, biceps, and serratus anterior.

Over the course of time, doing regular bench press helps increase upper body (chest, arms, shoulders) tone, strength, and endurance.


Squat works on your leg muscles and help strengthen tendons, bones, and ligaments. Additionally, squat is also an effective weight loss workout.


Deadlift involves hip and back movement. This helps add definition and tone to your upper and lower back, hamstrings, and glutes.


Snatch deadlift is a full body exercise that puts excessive stress on your biceps and hamstrings. Although the proper technique of snatching is difficult to master and the chance of muscle pull is high, snatch is one of the best workouts to improve endurance.

Chest Press

Chest press is another upper body workout. Three sets of chest press with 3 to 6 number of reps each can improve strength of muscles, bones, and tendons of arms, chest, and shoulders.

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