one rep max

How to Calculate and Use Your One Rep Max

by Evelyn Valdez

Regardless of personal fitness goals, every active person has different ways to measure their current level and progress. This is important because it allows you to see how far you’ve come and what you need to do to keep moving forward. For those in strength training, one of these measures is the one-rep max!

Your one-rep max or 1RM, short for one-repetition maximum, refers to the maximum amount of weight that you can lift in a single repetition while exerting maximum force – or just how heavy you can lift at once! If you want to make serious gains, knowing your one-rep max can be the ultimate tool for your goals.

In this article, we’ll tell you exactly how to calculate your one-rep max (1RM) and how to use it during your workouts to help you get closer to your strength training goals. But before we get started, let’s talk a little bit about how beneficial knowing your 1RM is…

Benefits of knowing your one-rep max

Knowing what your one-rep max is and how to use it is one of the best ways to measure your progress if you have strength-related or similar goals. Not only because you’re able to see how far you’ve come which increases motivation, but because you can modify your routine accordingly, which takes us to the next point…

You can build a strength training program around your one-rep max that actually works for you and your goals. Because you’re aware of exactly how much you can lift, you can choose your exercises and your reps based on that number instead of using a rough estimate, allowing for gradual improvement that naturally follows your progress.

For example, if you want to add barbell back squats to your routine, you can do so by choosing a fixed number of reps and a percentage of weight and sticking with it throughout your journey, like doing 5 reps at 85% of your 1RM every time. It’s convenient, effective, and can help you reach your goals much faster and safer!

How to calculate your one-rep max

Calculating your one-rep max is a multi-step process, but before doing that, there are a few things you need to know first…

  • Strength is exercise-specific. Your one-rep max won’t be the same for every exercise, because strength is relative, but you can test each major part of your body for accurate results (back, legs, and arms/shoulders/chest).
  • You need to warm up properly. This is particularly crucial when measuring your 1RM because you’ll be exerting the maximum amount of force that you possibly can.
  • Rest for at least 24 hours before testing. Tired muscles won’t produce the same output, so have at least a full rest day before testing your one-rep max so your muscles and joints are well-rested.
  • Always have a spotter! You’ll be lifting the absolute heaviest weight that you can manage, so you’ll want to make sure to have someone spotting you just in case things go south.

Keep these things in mind before you try to calculate your one-rep max, especially if it’s your first time doing so, to ensure that you get the most accurate results with minimal setbacks. Now, let’s get into how to calculate your one-rep max

Pick your exercise and warm-up

The first step is choosing the exercise you’ll be using to measure. Some of the most popular and accurate exercises for calculating your 1RM are back squats, deadlifts, and bench presses, but this is up to you and your goals.

When you’ve chosen the exercise, warm up accordingly! Aim to warm up for 15-25 minutes with some cardio and a variety of different dynamic stretches that mimic the exercise you’ll be doing to prepare the target muscle groups and minimize the risk of injury.

Use 50% of your expected 1RM to perform a few reps

Use a rough estimate of your one-rep max to begin preparing your body for the next steps. If you think your 1RM will be around 180 lb based on your history and current performance, use 90 lb to perform the first 6-10 repetitions to break into the exercise and get your blood pumping, then rest for at least two minutes.

Increase to 80% of your expected 1RM and perform a few more reps

Begin approaching your actual one-rep max by lifting 80% of your estimated 1RM – so around 144 lb of the initial 180. Because you already started lifting and you’re now dealing with a heavier weight, make sure to limit this step to just 2-3 reps before resting for at least one full minute.

Add 10% more weight to each rep until you hit your limit

This is where the real calculations start to happen. From now on, add 10% of the initial estimated weight to your load and perform a single rep with that new weight before resting for a minute and adding another 10%. Following the same example, your next rep would be with 162 lb, the next with 180 lb, and so on.

If you get to a point where adding 10% might be too much, you can start adding just 5% or even 2% until you can’t lift any more reps with proper form. The final amount of weight you could lift successfully is your one-rep max for that exercise – congrats!

Using your one-rep max for your goals

Now that you know what your one-rep max is, you can start using that information to build a new workout or modify your current one.

Of course, how you use your 1RM will depend on your specific goals, so let’s take a look at some of the most popular strength-related goals and how you can use your one-rep max to get closer to them.

Improving your strength

Ideal lifting weight: 85-95% of your 1RM

If your focus is on building muscular strength and being able to progressively lift heavier and heavier, you’ll want to aim for the higher end of your 1RM.

You need to be able to perform a few really heavy reps to push your muscles to the limit and develop your strength, so aim for around 2-4 reps at 85-95% of your 1RM, and make sure to rest for at least 2-5 full minutes to allow your muscles to recover properly from the short but intense set.

Improving your power

Ideal lifting weight: 80-85% of your 1RM

Speed plus strength equals power, so if your goal is to maximize your lifting power, you need to lift heavy and as quickly as possible.

Because you’ll be adding a speed element to your lifting, you need to be able to move the bar with more control, so 80-85% of your 1RM is a good percentage that still pushes your muscles to the limit. Stick to lower reps, around 3-5, and then rest for 2-3 full minutes before the next set.

Improving your muscle size

Ideal lifting weight: 65-85% of your 1RM

Big muscles look nice in the mirror, but they also go hand in hand with strength and power. If your goal is to get bigger, you need to focus on hypertrophy.

For this, you need to put your muscles under enough stress to achieve muscle fiber damage so that your body can repair the muscle and build new tissue on top. You'll want to stick to a lower 1RM percentage, around 65-85% of your current 1RM, do 7-12 reps, and then just under a minute of rest to keep pushing your muscles to the limit.

Improving your endurance

Ideal lifting weight: 55-65% of your 1RM

Endurance basically means how long you can go without breaking proper form, so it involves higher reps but lower weights to avoid early fatigue.

If you want to improve your endurance, aim for 12-20 reps at 55-65% of your 1RM, and only rest for a minute or less. This will allow you to exercise for longer while still fighting against a significant degree of resistance to increase muscular endurance.

Improving your explosiveness and speed

Ideal lifting weight: 30-50% of your 1RM

Finally, if your goal is to increase your movement speed and your explosive strength, you need to focus a lot more on how you move instead of how much.

Because of this, your weight lifted will be on the lower end of your 1RM, around 30-50%, performing around 3-5 reps and up to 6 sets. This way, you’ll be able to prioritize speed and explosive strength without getting too bulky, which can slow you down.

Calculate your one-rep max so you can maximize your gains

While knowing your one-rep max is a powerful tool, calculating it can be very taxing on your muscles, so make sure you only do it once or twice a year. And if you’re a beginner, don’t even worry about your 1RM just yet, just focus on building enough base strength and mastering proper exercise form!

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