The 3% Rule - The Muscle PhD

The 3% Rule

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Training intensity is a bit of a misnomer. Ask 10 bodybuilders how they define intensity and I would bet that 7-8 of them would describe it as the effort they exert during a training session. However, intensity is actually defined as the weight you are using and is typically described as a % of your 1RM – i.e. you could do 3 sets of 10 reps at 65% of your 1RM – that 65% is the intensity of the exercise.

There are other ways to track intensity, but the purpose of this article is to show an easy and applicable way to use percentages in your training. First and foremost, you’ll have to have a pretty good idea of what your 1RM is for at least the big three exercises (squat, bench, and deadlift). No worries if you don’t, we’ll show a way to estimate your 1RM and we’ll add future articles that discuss other ways to plan and track intensity.

With that out of the way, let’s dig in.

The 3% Rule

Anyone with a smidgen of common sense knows that your 1RM is obviously 100% of your 1RM. You don’t have to be a math wizard to figure that out. However, what percentage should you use for sets of 8? What percentage is your 3-rep max at? How can you estimate your 1RM from doing an 8RM? Enter, The 3% Rule.

The 3% Rule essentially states that every rep counts as 3%. Since that sentence doesn’t make much sense without context, here’s your context:

1RM = 100% 1RM

2RM = 97% 1RM

3RM = 94% 1RM

4RM = 91% 1RM

5RM = 88% 1RM

6RM = 85% 1RM

7RM = 82% 1RM

8RM = 79% 1RM

9RM = 76% 1RM

10RM = 73% 1RM

Make a little more sense now? Every rep you add over 1 reduces 3% from 100%. Now, it’s worth noting that each percentage coincides with a rep max. If your 8RM is 79%, that means you can do one all-out set of 8 at that weight. You probably won’t be able to do multiple sets of 8 at 79%. And, realistically, following the first set of 8, you probably won’t want to do more than one set.

How else can you apply this rule in training?

Applying the 3% Rule in Training

One of the more useful ways to use this rule is to estimate your 1RM. If you’re not a weightlifter or powerlifter, you’d be forgiven for not knowing your exact 1RM – it’s not necessary for your sport. However, you should have a pretty good idea of where your 6, 8, or even 10RM are at. Heck, you can even go test them during your next workout to get a better idea. Once you know these numbers, you can use The 3% Rule to estimate your 1RM. If you cranked out 8-reps at 200lbs on the bench press, you simply divide 200 by 0.79 to find your 1RM – 253lbs in this case.

Another common way to use these percentages is to utilize them as a yardstick for setting up sets and reps in a program. If you know your 8RM is 79% of your 1RM, you can plan sets of 8 reps around this percentage. If you want each set to end with 1 rep left in the tank, you can plan on doing, say, 3 sets of 8 reps at 76% – most coaches would probably just program 75% for simplicity. Those will still be pretty tough sets of 8, but you should be able to power through them.

Another way to use The 3% Rule is for figuring out what weights you should use on subsequent sets in a given workout. Let’s say you do your first set of 10 reps at 200-lbs and you know you had at least 2 more reps in the tank. Since each rep is 3%, you can simply add 6% to 200-lbs to find the weight you’ll use for your next set – i.e. 212lbs in this instance (210 or 215, obviously).

Where Does The 3% Rule Not Work as Well?

The 3% Rule is incredibly useful for sets up to 10 or 11 reps. Anything beyond that can get a little murky as you’ll start to get more involvement of other energy systems. This can also be dependent on individual differences, the muscle being trained, and training background.

Some people can simply perform more reps at a given intensity than others. Moreover, people can often perform significantly more reps at a given intensity with lower body exercises compared to upper body exercises (3). Why is this the case? Lower body muscles typically have a greater percentage of slow twitch muscle fibers. Since these muscles take longer to fatigue, people can generally perform more repetitions at a given intensity on lower body exercises than they can on upper body exercises (1).

Training background can also influence how many reps you can perform at a given intensity. If you also perform a good amount of endurance training, you’ll probably be able to do more reps at a given intensity compared to a lifter who doesn’t have as good of a cardio capacity (2).

Lastly, your lifting form can also play a role here. When we discuss these percentages, we’re assuming your form stays perfect, or at least mostly perfect, throughout the entire set. Can you do 8 reps at 85% of your 1RM on squat? Absolutely. I’ve done it several times and have made many clients do it as well. Are the last 2 reps perfect squats? Not at all – that’s not the point of that challenge. Sometimes you have to go above and beyond these estimations to truly challenge yourself for growth. Obviously, you need a spotter to try this and it’s mostly only going to be possible on lower body exercises.


In much of my own training and training prescriptions, I have used The 3% Rule with great success. If you’re looking for an easy way to plan and track your own training intensity, give The 3% Rule a shot and see how it works for you. Like I said earlier, we’ll be writing more articles about various ways to track and plan intensity, so if you don’t love this method, keep your eyes peeled for the next one in the series.


  1. Douris, P. C., White, B. P., Cullen, R. R., & Keltz, W. E. (2006). The relationship between maximal repetition performance and muscle fiber type as estimated by noninvasive technique in the quadriceps of untrained women. Journal of Strength and Conditioning Research, 20(3), 699.
  2. Richens, B., & Cleather, D. J. (2014). The relationship between the number of repetitions performed at given intensities is different in endurance and strength trained athletes. Biology of Sport, 31(2), 157.
  3. Shimano, T., Kraemer, W. J., Spiering, B. A., Volek, J. S., Hatfield, D. L., Silvestre, R., … & Newton, R. U. (2006). Relationship between the number of repetitions and selected percentages of one repetition maximum in free weight exercises in trained and untrained men. The Journal of Strength & Conditioning Research, 20(4), 819-823.

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