Knowledge base/Training basics
How many reps should you do?
In short
For muscle size, a wide span of rep ranges works, from heavy sets of 8 or fewer to light sets of more than 15, as long as the sets are hard. For maximal strength, heavier sets do better. A range of 6 to 12 reps covers both goals well, which is why most plans live there.
Cody de LeeuwLast checked 27 October 2026 · 6 min read
What do reps have to do with weight?
Reps and weight are two sides of the same choice. The heavier the weight, the fewer reps you can do. If you can lift a weight for 5 reps and no more, that is your 5-rep max (5RM). A weight you can lift 12 times is your 12RM.
So “how many reps” also means “how heavy”. Researchers often group sets like this:
| Group | Reps to failure | Feels like |
|---|---|---|
| Heavy | 8 or fewer | Slow reps, long rests, technique matters |
| Moderate | 9 to 15 | The usual gym range |
| Light | More than 15 | Light weight, burning effort, short on breath |
Those cut-offs come from a 2021 meta-analysis.2 They are conventions, not walls. A set of 8 and a set of 9 are nearly the same thing.
Which rep range builds the most muscle?
Less than people think. For decades, the textbook said 8 to 12 reps for size. The trials say a much wider range works. A 2021 review makes the same case: muscle can grow across a wide spectrum of loads, so the old “one best zone” idea does not hold up.5
- A review of 21 trials compared low loads (60% of your 1RM or less) with higher ones. All sets went to failure. Muscle growth was similar in both groups.1
- A network meta-analysis of 28 studies and 747 adults split loads into heavy (8 reps or fewer), moderate (9 to 15) and light (more than 15). It found no difference in muscle growth between them.2
- In a small 8-week study of 17 trained men, 3 sets of 10 and 7 sets of 3 gave similar gains in arm muscle size.4
One condition runs through all of this: the sets were hard. Most were taken to failure. Ten easy reps with a light weight is not the same as ten reps that you barely finish. Do you need to train to failure? covers how close is close enough.
Which rep range builds the most strength?
Here heavier does win. In the same two reviews, gains in maximal strength were larger with heavy loads than with light ones.12 In the 17-man study, the group doing sets of 3 improved their bench press max more than the group doing sets of 10.4
This fits how strength works. Lifting a heavy bar is a skill. Practising it with heavy bars makes you better at it. For experienced lifters, the ACSM position stand recommends working towards heavy loads of 1 to 6 reps, with long rests between sets.3
The gap is not huge, though. The network meta-analysis found a clear strength advantage for heavy and moderate loads over light ones, and only a small, not statistically significant edge for heavy over moderate.2 If your goal is a bigger squat, you do not need to live at 3 reps. You do need some heavy sets.
So what should you actually do?
Pick ranges that suit the exercise, then use the rep range to decide when to add weight. A common split:
| Type of exercise | Typical range | Why |
|---|---|---|
| Heavy barbell lifts (squat, bench, deadlift) | 5 to 10 | Heavy enough to build strength, with room to add reps. Very high reps get hard to do with good form. |
| Machines and most dumbbell work | 8 to 12 | Easy to load in small steps and to stop safely. |
| Small isolation lifts (curls, lateral raises, calf raises) | 10 to 15 or more | Light weights, small steps. A heavy single is awkward and gains little. |
This is coaching practice, not a result from a trial. The research says wide ranges work. The table picks the part of that range where each exercise is easiest to do well.
Mixing ranges is common: heavier on the big lifts, lighter on the small ones.
What is the range for, once you have picked it?
A rep range is also your signal for when to go heavier. With a range of 8 to 12, you stay at one weight until every set reaches 12. Then you add weight and start again near 8. That method is called double progression.
It means the range should be about 4 reps wide. A range of 10 to 10 gives you nothing to progress with. A range of 5 to 20 is so wide that your sets change completely along the way.
Moderate evidence
Several meta-analyses of controlled trials agree on the main points. Most trials are short (6 to 12 weeks) and use young, healthy adults, and sets were usually taken to failure. The practical ranges below are coaching practice. How we rate evidence
How Mitta does it
A range for every exercise, picked for you.
When Mitta builds your plan, every exercise gets a rep range based on its role and your goal. You see it as sets × reps in the workout. Your lift target then moves inside that range.
- By roleMain lifts 6 to 10 reps, secondary lifts 8 to 12, isolation exercises 10 to 15.
- Strength goalMain lifts drop to 4 to 6 reps and secondary lifts to 6 to 10. Isolation stays at 10 to 15.
- Fits the exerciseThe range is kept within what that exercise allows. If it ends up too narrow for double progression, it is widened.
- A target inside itEach set has a target of weight and reps. Hit the top of the range on every set and the weight goes up.
Stop guessing your reps.
Mitta gives every exercise a rep range and tells you what to aim for in each set. Free to start, in the web app for invited testers.
Questions about
How many reps should you do
Is 8 to 12 reps really the best range for muscle?
It is a good one, not the only one. Trials find similar muscle growth from heavy, moderate and light loads when the sets are hard. 8 to 12 is popular because it is easy to load and easy to stop safely.
Are high reps (20 to 30) worth doing?
They can build muscle if you take them close to failure. They are tiring, since the last reps burn, and they suit small exercises better than heavy squats. For strength they do less than heavy sets.
Do I need to do heavy singles to get strong?
No. The studies above compared sets of 8 or fewer, such as sets of 3, with lighter ones. None tested singles specifically. Sets of 3 to 6 on the big lifts are enough to practise heavy weights.
Should I change my rep range over time?
You can. Many plans move between heavier and lighter blocks. Changing the range now and then is fine, but it is not required for progress. Adding reps or weight over time is what counts.
Sources
- Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. Journal of Strength and Conditioning Research, 2017; 31(12): 3508–3523. doi.org/10.1519/JSC.0000000000002200
- Lopez P, Radaelli R, Taaffe DR, et al. Resistance training load effects on muscle hypertrophy and strength gain: systematic review and network meta-analysis. Medicine & Science in Sports & Exercise, 2021; 53(6): 1206–1216. doi.org/10.1249/MSS.0000000000002585
- American College of Sports Medicine. Progression models in resistance training for healthy adults. Medicine & Science in Sports & Exercise, 2009; 41(3): 687–708. doi.org/10.1249/MSS.0b013e3181915670
- Schoenfeld BJ, Ratamess NA, Peterson MD, Contreras B, Sonmez GT, Alvar BA. Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men. Journal of Strength and Conditioning Research, 2014; 28(10): 2909–2918. doi.org/10.1519/JSC.0000000000000480
- Schoenfeld BJ, Grgic J, Van Every DW, Plotkin DL. Loading recommendations for muscle strength, hypertrophy, and local endurance: a re-examination of the repetition continuum. Sports, 2021; 9(2): 32. doi.org/10.3390/sports9020032
Written by Cody de Leeuw. First published , last checked 27 October 2026. This article is general information, not medical advice. Spotted a mistake? Tell me