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Online 1RM (One Rep Max) Calculator
Our online 1RM (One Repetition Maximum) calculator will calculate the maximum weight you can lift for one repetition of a specific exercise, such as squats or deadlifts. It’s a useful metric that will help you properly plan your strength training and improve your performance in the gym.
How to use the 1RM calculator?
- Choose the exercise for which you want to calculate 1RM (e.g., squat, bench press, deadlift).
- Enter the required input data into the calculator.
- Enter the data into the calculator.
- Weight: barbell weight (in kg)
- Repetitions: number of completed repetitions
- RIR (Reps in Reserve): Estimate how many more repetitions you could do. If you went to complete failure, enter 0.
- Here’s an example. If you did five squats with 60 kg and felt you could do two more, enter weight 60 kg, 5 repetitions and RIR value of 2.
- The calculator will provide you with your 1RM value.
For greater accuracy, load a weight with which you can perform 4-6 repetitions. Do a set to muscle failure or close to it, and enter the necessary data into the calculator based on this.
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What is your maximum strength?
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Your calculated 1RM is:
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| % 1RM | Load |
|---|---|
| 70% | – |
| 75% | – |
| 80% | – |
| 85% | – |
| 90% | – |
| 95% | – |
What is 1RM, 1RIR, and why are they important for your progress?
1RM or One Repetition Maximum represents the heaviest weight you can lift with proper form and full range of motion for one repetition. If your 1RM increases, it’s a clear indicator that your strength is growing. [2]
However, the maximum isn’t just used to track successful progress, but also to set up a training plan in terms of load weight to match your goals. Depending on what you want to achieve through training, you calculate the percentage of your 1RM and then train with the calculated weights.
| Training Goal | % of 1RM | Reps per Set | Recommended Rest |
|---|---|---|---|
| Increasing Maximum Strength | 85-100% | 1-5 | 3-5 min |
| Hypertrophy (Muscle Growth) | 70-85% | 6-12 | 1-2 min |
| Strength Endurance | 65% | 15+ | 30-60 sec |
[1]
If you need help creating workouts, get inspired by our articles.
How does RIR come into play?
RIR (Repetitions in Reserve) value, meaning repetitions in reserve, expresses the number of repetitions you could still perform before reaching muscle failure (RTF – Repetitions to Failure). This data helps estimate 1RM more safely and gently because you don’t have to perform the set to complete failure.
- RIR = 0 means you went to absolute failure (RTF). In practice, this means that after completing the set, you couldn’t perform any additional repetitions.
- RIR = 2 means that after completing the set, you felt you could do two more repetitions before reaching failure.
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How does the 1RM calculator work?
You can test your maximum using the direct method, which requires gradually increasing the weight over several attempts until you can only manage one repetition with the current maximum weight. While this test is effective, it’s also exhausting, time-consuming, associated with a higher risk of injury and isn’t suitable for beginners.
Our calculator uses the principle of indirect estimation (the RTF method). This means it uses the number of repetitions to failure with a submaximal weight to calculate the maximum. It can also account for RIR, making the calculation even more practical and safer.
To ensure maximum accuracy and consistency, the calculator uses an average of three scientifically validated formulas:
- Lombardi: This formula is often considered the most accurate.
- Epley: The most popular and historically most used formula in strength training.
- Brzycki: Often provides slightly lower estimates, which is beneficial for minimising overload risk when planning workouts.
How to correctly interpret and use the result in training?
Besides the 1RM value itself, the calculator will provide you with a table of calculated percentage values. You’ll immediately know what 70%, 75%, or 80% of your maximum is.
Practical application:
- Training setup: If your calculated squat 1RM is 100 kg and your goal is muscle growth (65-85% 1RM), you might choose a load of 75% 1RM, which is 75 kg. You then work with this weight for the specified number of repetitions, ranging from 6-12.
- Measuring fatigue and recovery: If the calculator shows a decrease in 1RM during regular testing (e.g., every 4-6 weeks) (for example, by 5-10%), it might be a red flag indicating you need to temporarily reduce intensity or adjust recovery (sleep, nutrition, etc.).
If you want to know more about how many repetitions you should do in training, read the article How Many Reps Should You Do to Lose Weight or Gain Muscle?
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Who is the calculator suitable for and what are its limitations?
- For beginners and intermediates, it’s a safe and reliable strength estimate without the need to undergo risky direct testing.
- For advanced athletes, it allows quick assessment of current strength and fatigue status without disrupting recovery through maximal testing.
- For trainers, it represents an excellent tool for planning training intensity for clients.
What are the calculator’s limitations?
All 1RM estimation formulas lose accuracy when your test repetition count is higher than 10. Sets above 10 repetitions measure muscular endurance rather than maximum strength. For the most accurate results, it’s recommended to test in the range of 4 to 6 repetitions. [3,4]
What Should You Remember?
The 1RM calculator is currently the most practical and safest tool for obtaining key data for effective strength training planning. Find out your maximum and start training more intelligently.
Try our 1RM calculator and take your training to the next level!
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