One Rep Max Calculator - 1RM Calculator & Max Weight Calculator
Use this One Rep Max (1RM) Calculator to estimate the maximum weight you can lift for a single repetition based on the number of repetitions you can perform with a certain weight. For the most accurate estimate, please use a weight that you can lift between 1 and 10 times. Refer to the "Estimation methods" section for more detail on the formulas used and how this calculator works.
Last updated: October 19, 2025
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For the most accurate estimate, use a weight you can lift between 1 and 10 times.
One Rep Max Result
Your One Rep Max (1RM)
116.67 kg
Using Epley formula
Training Percentages
| % of 1RM | Weight | Training Goal |
|---|---|---|
| 50% | 58.33 kg | Explosive Power |
| 60% | 70.00 kg | Explosive Power |
| 70% | 81.67 kg | Muscle Endurance |
| 80% | 93.33 kg | Muscle Growth |
| 85% | 99.17 kg | Muscle Growth |
| 90% | 105.00 kg | Strength & Power |
| 95% | 110.83 kg | Strength & Power |
| 100% | 116.67 kg | Strength & Power |
Training Recommendations:
- • 50-60% of 1RM for 3-5 reps: Explosive power
- • ~70% of 1RM for 10-15 reps: Muscle endurance
- • 70-80% of 1RM for 7-12 reps: Muscle growth
- • 80-100% of 1RM for 1-3 reps: Strength & power
Note: These are estimates. For the most accurate 1RM, use a weight you can lift for fewer reps (1-5). Always use proper form and consider using a spotter when training near your maximum.
A "one rep max" (one-repetition maximum) is the maximum weight a person can lift for one complete repetition of a specific exercise while maintaining proper form. It is a measure that is commonly used in weightlifting competitions since it represents the peak force that a person's muscles can generate in an all-out effort.
A person's one rep max typically differs based on the exercise, whether it be a bench press, squat, deadlift, overhead press, or whatever other exercise is being performed. Thus, it is important to measure a one rep max for a given exercise rather than applying a one rep max in one exercise to other exercises.
Why One Rep Max is Important
Knowing your one rep max (1RM) is valuable because it provides a quantitative measure (or estimate) of your maximal strength for a given exercise, which enables you to design a workout program and train accordingly based on your goals.
For example, you can use your 1RM to manage your targeted training intensity. This enables you to design a workout program that is challenging enough to promote strength gain while also ensuring proper technique and safety.
Since it provides a quantitative measure, knowing your 1RM also allows you to track your strength progress over time and set goals for improvement. Without a quantitative measure, it can be difficult to motivate ourselves to train. Seeing improvement in your 1RM can help motivate you to train, or if you don't see improvement, you can use your 1RM to adjust your workout program to help you achieve your desired strength gains.
How to Measure One Rep Max
The two primary methods for measuring one rep max are direct measurement by performing a strength test for a given exercise and using estimation methods. There are advantages and disadvantages to using either method, as described below.
How to Directly Measure One Rep Max
Directly measuring one rep max involves progressively increasing the weight as you perform a specific exercise. As you increase the weight, taking breaks between each trial, the number of repetitions of the exercise you can perform should continue to decrease until your muscles reach failure and you can only perform one repetition of the exercise with proper form.
This method of measuring one rep max can be dangerous, and it is important to only attempt using direct measurement for exercises you are experienced in performing, ideally with the help of a spotter. The steps for directly measuring your one rep max are generally as follows:
- Warm up: Begin by warming up the muscle groups you will be using.
- Find a spotter: Finding your one rep max involves pushing your limits. Having a spotter helps you do this in a safe manner.
- Start with a comfortable weight: The weight you select shouldn't be too light. It should be a weight you know you can lift for ~5-10 reps, but not a weight that you can lift for many more.
- Rest and recover: Between each set, you should rest and recover fully before attempting the next set. Your break may last anywhere from 2-5 minutes.
- Progressively increase weight: After enough rest, attempt the next weight. Depending how you felt on the first set, you may find yourself wanting to increase the weight significantly if the first set was too easy, or you may find that the first weight you selected was more difficult and closer to your 1RM than expected.
- Repeat the process: Continue the process of resting and recovering and progressively increasing weight. Once you can only do one repetition with good form, you have found your estimated one rep max.
- Record your estimated 1RM: Note your 1RM and save it somewhere.
- • Straightforward: Keep lifting more weight until you can only do one proper repetition
- • More accurate: Direct measurement is relatively accurate, especially compared to estimation methods
- • Higher risk of injury: The risk of injury is higher since the goal is to lift more and more weight until failure
- • Time consuming: Since you need ample rest between each attempt, direct measurement takes more time
How to Estimate One Rep Max
There are various formulas used to estimate one rep max. This calculator provides calculations for the Epley, Brzycki, and Lombardi formulas:
1RM = Weight × (1 + Reps/30)1RM = Weight × (36 / (37 - Reps))1RM = Weight × (Reps^0.10)The formulas are relatively straightforward; to use them, just plug the amount of weight lifted and the number of repetitions at that weight for a given exercise. The two most popular formulas are the Epley and Brzycki formulas. These formulas return similar results and are generally within 10% or so of a person's actual one rep max, though in some cases it can vary to a larger degree. For the most accurate estimate, use a weight you can lift for fewer reps (1-5 repetitions).
Steps to Estimate 1RM:
- 1. Select a challenging but safe weight: Pick a weight you can lift for between 3-10 reps. The lower the number of reps to failure, the higher the accuracy.
- 2. Repeat until failure: Keep resting and increasing the weight until you reach failure within 3-10 reps.
- 3. Record the weight and number of reps: Record the weight and number of reps completed with proper form, then plug them into the calculator.
- • Lower risk of injury: You are lifting lower weights for more reps
- • Time efficient: Much quicker than directly finding 1RM
- • Accessible: More accessible to beginners and those with physical limitations
- • Less accurate: Formulas are less accurate than direct measurement, especially for beginners
- • Based on experienced lifters: Formulas are based on data from experienced lifters, so may be less accurate for beginners
How to Use One Rep Max
Once you have measured your one rep max, you can use it to help manage your targeted training intensity based on your strength goals. In general, lifting at a certain percentage of your one rep max promotes different things. Below is a general guideline for targeting strength, endurance, and muscle growth:
Lifting a lower number of reps at a lighter weight can help with promoting explosive power. Since it is a lighter weight and lower number of reps, try to keep the breaks between your sets shorter.
Lifting at around 70% of your 1RM for more repetitions helps promote muscle endurance.
Lifting in this range can help with muscle growth.
Lifting in this range promotes a combination of muscle growth, power, and overall strength. Since you are training within or at the upper range of your one rep max, use a spotter whenever possible to decrease risk of injury.
How to Improve One Rep Max
Prioritize Safety
- • Prioritize proper form: Form can almost always be improved. Be conscious and dedicated to learning and maintaining proper form, especially when near your limits.
- • Get a spotter: Whenever possible, and especially when attempting heavier weights, train with a spotter. A spotter can help prevent injury both directly and by observing your training and form.
Train Consistently
Building strength requires consistency. It is much more difficult to build strength than it is to maintain it.
- • Adjust weight and repetitions appropriately: When trying to improve one rep max, you should try to train at 85%-100% of your one rep max. On any given day, we may not feel up to training at 100%, but training at 70% is still better than not training.
Rest
It is definitely possible to overtrain. Muscles need time to recover and grow, and pushing them to their limits constantly can negatively impact your strength goals, especially in the case of injury. If your muscles are too fatigued, you will not be able to train them as effectively, and are more likely to injure yourself.
Vary Your Workouts
In the beginning, just repeatedly performing the exercise you want to improve will likely result in strength gains. However, eventually it will likely lead to a plateau. This is in part because muscles adapt, and at some point will need to be trained differently in order for you to observe further strength gains.
- • Try different types of sets: Supersets, compound sets, pyramid sets
- • Train your surrounding muscles: Training supportive muscles reduces risk of injury and may help with overall strength, especially if you're at a plateau
One Rep Max Calculator Examples
Input Values:
- Weight Lifted: 100 kg
- Repetitions: 5 reps
- Formula: Epley
Calculation:
Result: One Rep Max = 116.7 kg
This means you can estimate lifting 116.7 kg for one repetition based on being able to lift 100 kg for 5 repetitions using the Epley formula.
Disclaimer: Always consult with a qualified fitness professional or healthcare provider before engaging in maximal strength testing or starting a new exercise program. Safety should be the top priority when assessing and training for maximal strength.
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