Weight Training Intensity: How Many Reps Per Set Of An Exercise?

Weight training intensity basically refers to how much weight you will be lifting and how heavy or light that weight is for you on a given exercise.

The lighter the weight/easier it is for you, the lower the intensity. The heavier the weight/harder it is for you, the higher the intensity.

And, all of this intensity stuff is usually predicted by one thing: how many reps you’re doing per set.

Reps (short for “repetitions”) are the number of times you move a weight from point A to point B during a set of an exercise. The lighter the weight, the more reps you will be able to lift it for. The heavier the weight, the fewer reps you’ll be able to lift it for.

Obvious, I know. But, as you can see, reps and intensity go hand in hand most of the time. Meaning…

  • The more reps you can lift a weight for = the lower your training intensity is.
  • The fewer reps you can lift a weight for = the higher your training intensity is.

The reason this is important to us is because certain levels of intensity are more ideal for certain goals than others (due to factors like time under tension, muscle fiber recruitment, etc.).

And this leads to an important question: what weight training intensity is best for your goal?

Or, to put it another way, how many reps should you do per set of an exercise? Let’s find out…

The Ideal Rep Range For Various Weight Training Goals

Here now are the most commonly used rep ranges along with their primary training effect:

  • 1-5 Reps Per Set = Mostly Strength
  • 5-8 Reps Per Set = Strength AND Muscle Equally
  • 8-10 Reps Per Set = Muscle With Some Strength
  • 10-12 Reps Per Set = Muscle With Some Endurance
  • 12-15 Reps Per Set = Endurance With Some Muscle
  • 15-20 Reps Per Set = Mostly Endurance

So, as you can see:

  • Lower reps (high intensity) is most ideal for increasing strength.
  • Higher reps (low intensity) is most ideal for improving muscle endurance.
  • Moderate reps in the middle of the two (moderate intensity) is most ideal for building muscle and really anything related to improving the way your body looks (rather than performs).

Now, the key word I’m using here is “ideal.” Just because I didn’t put “strength” next to the 10-12 rep range doesn’t mean you will never be able to increase strength when doing 10-12 reps of an exercise. That’s not true at all.

In fact, each rep range shown is capable of producing some amount of strength, muscle, and endurance results. However, the objective here is to choose the rep range that is most ideal for your specific goal, because that’s the one that will work best for the results you want.

Oh, and if you’re wondering why there is no rep range that is ideal for “tone” or “definition” or “fat loss” or anything similar, it’s because, metabolic training aside (a topic for another day), there really is no such thing.

The whole “high reps makes you toned/defined/ripped/lean/etc.” concept is pure bullshit. I cover this in more detail in my post about muscle tone.

The take home message is that, from a training intensity standpoint, these goals all fall into the same category as “muscle” on the chart shown above. The same rep ranges are ideal.

Weight Training Intensity Recommendations

So, when it comes to intensity and figuring out how many reps you should do per set, here are the most widely accepted recommendations based on science and real world results…

  • If your primary goal is increasing strength, then you should mostly train in the lower rep ranges (between 1-8 reps per set) and therefore at a higher intensity.
  • If your primary goal is building muscle (or anything related to improving the way your body looks), then you should mostly train in the moderate rep ranges (between 5-12 reps per set) and therefore at a moderate intensity.
  • If your primary goal is improving muscle endurance, then you should mostly train in the higher rep ranges (between 12-20 reps per set) and therefore at a lower intensity.

Two Other Intensity Related Factors

Before leaving the subject of weight training intensity, there’s actually two other subjects/questions that are directly influenced by what rep range you end up using. They are:

  • Determining How Much Weight To Lift
    Once you know how many reps you’ll be doing per set of an exercise, the next thing you need to determine is how much weight you need to lift for each exercise to end up in that ideal rep range. I explain how to do that here: How Much Weight Should You Lift For Each Exercise?
  • Training To Failure
    Another topic directly related to training intensity is training to failure (the point where you can’t complete another rep). The question is, should you train to that point, or should you end a set before reaching that point? I cover this topic right here: Should You Train To Muscle Failure?

What’s Next?

Now that you know how many reps per set is most ideal for your goal, the next thing you need to figure out is how many TOTAL reps, sets and exercises you should do per workout, per week and per muscle group. Let’s find out…

Weight Training Volume – How Many Sets, Reps & Exercises?

(This article is part of a completely free guide to creating the best workout routine possible for your exact goal. It starts here: The Ultimate Weight Training Workout Routine)

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Jay is the science-based writer and researcher behind everything you've seen here. He has 15+ years of experience helping thousands of men and women lose fat, gain muscle, and build their "goal body." His work has been featured by the likes of Time, The Huffington Post, CNET, Business Week and more, referenced in studies, used in textbooks, quoted in publications, and adapted by coaches, trainers, and diet professionals at every level.