Are 15-Inch Arms Big? A Guide to Getting Respectable Arm Muscles

If you’re on a fitness journey, you’ve probably asked yourself: How much is enough? How big is too big? What’s a good size for your arms to be? According to the research, 15 in (38 cm) arms are above average and a great goal, but we’ll break it down for you and explain what a good arm size is, the average arm size, and what makes your arms larger. Then, we talked to fitness experts, personal trainers, and physical therapists to show you the best ways to achieve your arm gains.

What’s a good arm size?

According to the CDC’s research, most adults’ arms are about 12–13 in (30–33 cm). This means that 15-inch arms are well above average and are something to be proud of, as well as a good fitness goal. Of course, everyone’s body is different, and some people build muscle more easily than others.

Section 1 of 8:

Are 15-inch arms a good size?

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Yes, 15-inch arms are an impressive size on pretty much anyone. According to the CDC’s study on average arm sizes, 15 in (38 cm) is well above average, even for adult males, who have the highest potential for large arms.^{[1]
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Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services

Go to source} If you have 15-inch arms, then congrats! You’re officially stacked. And if you don’t have them yet, they’re a pretty decent goal, provided you’re willing to work for them!
- Keep in mind, though, that everyone’s body is different, and while 15 in (38 cm) is a good goal, it might be easier for some people to hit that goal, and harder (or impossible) for others, depending on your physique and genetics.
Meet the wikiHow Experts

Monica Morris is an ACE Certified Personal Trainer based in the San Francisco Bay Area with over 15 years of fitness training experience.

Laila Ajani is a Fitness Trainer and founder of Push Personal Fitness, a personal training organization based in the San Francisco Bay Area.

Joel Giffin, PT, DPT, CHT, is a Doctor of Physical Therapy and the Founder of Flex Physical Therapy in New York, New York with over 15 years of experience.

Alex Robles, MD, NASM is a Certified Personal Trainer and the Founder of the White Coat Trainer. He helps professionals get strong, build muscle, and lose fat.

Section 2 of 8:

Average Arm Sizes

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Adults’ arms are about 12–13 in (30–33 cm), on average. The CDC study examined the arm circumferences of about 10,000 people and found that on average, adult men have arms that are about 13 in (33 cm) around.^{[2]
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Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services

Go to source} Of course, that’s not just pure muscle, but a plain measurement of fat, bone, and muscle—measuring pure muscle would be impossible. Interestingly, older people who are about 40-60 years old tended to have the meatiest arms across the board.
- Adult women’s arms are about 12 in (30 cm), on average.
- The largest men’s arms were about 17 in (43 cm), and the largest women’s arms were about 15.5 in (39 cm).
- Keep in mind that the people who participated in the study were randomly selected, not just bodybuilders! Most of them were normal, everyday people.
- Remember that every body is different! These are just averages and not a measurement of muscle mass. Having leaner or thicker muscles than average doesn’t necessarily make you more or less fit than other people.
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Pro bodybuilders’ arms are often larger than 20 in (51 cm). If we’re looking just at bodybuilders and people who strive to grow their arms as large as possible through careful dieting and extreme workouts, then the story is a little different. Here are some reported arm sizes of famous athletes:^{[3]
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- Arnold Schwarzenegger: 22 in (56 cm)
- Sergio Oliva: 20.5 in (52 cm)
- Ronnie Colman: 22 in (56 cm)
- Phil Heath: 23 in (58 cm)
- Mamdouh Elssbiay: 24 in (61 cm)
- Renné Toney: 21 in (53 cm)^{[4]
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Section 3 of 8:

How big should my arms be?

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Aim for above average, but understand that it depends on many factors. There’s no equation or magical process for telling you how big your arms “should” be. That’s up to you and your body! Your target will vary based on your height, weight, muscle mass, fat mass, age, and lifting ability. In general, it doesn’t hurt to aim to surpass the average size of 12–13 in (30–33 cm), but that journey will look different for everyone.^{[5]
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- For a personalized, tailored fitness regimen to help you reach your ideal body, see a personal trainer, who can interact with you in person and review your health history to find a fitness plan that works for you.
- Bodybuilders, for example, aim to get their arms as large as possible. More casual fitness enthusiasts often just work until they’re happy with what they see in the mirror. It’s up to you!

Section 4 of 8:

Arm Anatomy

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Your arm size is mostly determined by your biceps and triceps. Most of the bulk of your upper arms comes from 2 particular muscles. Your biceps, which are located on top of your arms and which flex when you bend your elbow, are what you usually think of when you think of muscle mass. But your triceps, which are on the back of your arms, also greatly contribute to your arm size.^{[6]
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Cleveland Clinic
Educational website from one of the world's leading hospitals

Go to source} When training for bigger arms, focusing on these 2 muscle groups will bring the greatest results.^{[7]
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- How much fat is in your arms also contributes to arm size. And no, it’s not “cheating” to have big arms due to fat content, but more muscle does equal more strength.

Section 5 of 8:

Measuring Your Arms

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Flex your bicep parallel to the ground and measure around it. Measure before and after your workout so you have the most detailed measurements—your arms are often a bit larger after a pump, or a round at the gym. Certified personal trainer Monica Morris tells us to flex our arms with our elbow bent and arm forward.^{[8]
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Expert Source

Monica Morris
Certified Personal Trainer

Expert Interview} Then, wrap a soft measuring tape around your arm at the thickest point to take a reading.
- Or, wrap a length of string around your arm, mark where the string overlaps, then straighten it out alongside a measuring tape to find your measurement.
- Measure both arms, too! One arm may be larger than the other, which just means you’ll have to focus on it a little more in your workouts.

Section 6 of 8:

Exercises for Growing Your Arms

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Push-Ups Push-ups are some of the simplest and most effective workouts for growing your arms. To do them, get on all fours on a firm surface, then raise yourself onto your palms and toes, with your hands at about shoulder width. Then, fitness trainer Laila Ajani explains that, while keeping your body in a straight line, lower yourself so that your nose touches the floor, pause, then gradually raise yourself back up.^{[9]
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Expert Source

Laila Ajani
Fitness Trainer

Expert Interview} Keep your elbows close to your torso.
- Aim to do 2-3 sets of 10 reps per workout.
- Vary your sets by positioning your hands closer or further apart. Closer hands target your biceps and chest, while wider hands target your shoulders and triceps.
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Dips Dips are another easy (virtually) no-equipment workout that targets your triceps. Find a sturdy, low surface, like dip bars or a stationary chair. Stand facing away from it, and reach back so that your hands grip the surface. Extend your legs straight out so that your butt hovers off the ground. Then, slowly lower yourself until your elbows form right angles, then raise back up gradually.^{[10]
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- Aim for 2 sets of 5-8 reps per workout.
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Chin-Ups To do a chin-up, stand directly beneath a chin-up bar. Grip the bar with your palms about as wide as your shoulders, facing toward you. Then, Morris tells us to steadily engage our arms while crossing one shin over the other for stability.^{[11]
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Expert Source

Monica Morris
Certified Personal Trainer

Expert Interview} Pull yourself upward until your chin is level with the bar, then exhale and slowly lower yourself.
- To start, do as many chin-ups as you can. Long-term, aim to do 20-30 in a single workout.
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Barbell Curls To do a barbell curl, sit or stand with your back straight and hold the barbell in both hands. Position your hands at about shoulder-width with your palms facing up. While moving only your elbows and keeping your upper arms stationary, bring the barbell up to your chest, pause, then slowly lower it back down.^{[12]
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- Aim to do 3 sets of 10 reps per workout.
- Start with the bare bar, then add weight in small amounts as needed.
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Dumbbell Curls To do a bicep curl, sit or stand with your back straight. Hold a dumbbell in one hand with your palm facing up, says physical therapist Joel Giffin, PT, DPT, CHT. Keep your elbow at your side, then slowly lift the dumbbell, bending your arm at the elbow. Hold it at its peak for a moment, then slowly lower it. Dr. Giffin tells us to engage our shoulder blades and keep them squeezed together.^{[13]
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Joel Giffin, PT, DPT, CHT
Physical Therapist

Expert Interview}
- Aim to do 3 sets of 10 curls per arm per workout.
- Start with lightweight dumbbells, then add weight if the motion feels too easy. You want manageable, consistent resistance.

Section 7 of 8:

Growing Muscle Faster

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Give your arms a good workout 2-5 times a week. More isn’t necessarily always better. Your body needs time to rest and recoup, and that’s when the muscles are actually repairing and building. To build arms, focus on them in your workouts a few times a week, then move on to other areas of your body to make sure you’re getting the most out of your routine.^{[14]
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- For a good starting point, pick 3-5 of the exercises above and do 10-20 total sets of each per week.^{[15]
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Mix up your routines and reps, but always train close to failure. Your arms are made up of several muscle groups, and focusing on just 1 or 2 exercises neglects the other muscle groups that also contribute to arm size. To make sure you’re getting the most growth, mix it up! Vary your exercises, and even how many reps you do. No matter what, though, keep going until you’re “close to failure,” or until you feel like you can’t complete another set.^{[16]
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- Keep track of how many reps you’re able to do each time, and aim to keep adding to the amount each workout.
EXPERT TIP

Alex Robles, MD, NASM
Certified Personal Trainer
Dr. Alex Robles is a Physician, Certified Personal Trainer, and the Founder of the White Coat Trainer. Dr. Robles specializes in helping busy professionals get strong, build muscle, and lose fat. He holds a BS in Biology and an MD from Cornell University. He completed his OB/GYN Residency at New York Presbyterian Cornell. Dr. Robles is also a NASM Certified Personal Trainer.

Alex Robles, MD, NASM
Certified Personal Trainer

You can't do the exact same workout over and over and expect to build muscle or make progress. You need to have some measurable way of indicating that your workouts are improving. The simplest way of doing this is by doing more repetitions.
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Get about 1.1 to 1.5 grams of protein per kg of bodyweight. Eating protein is key for building muscle and getting bigger arms, since it helps repair and regrow muscles when you tear them by working out. You need enough protein to build muscle, but not too much, since excess protein gets stored as fat, not muscle. In general, experts recommend getting 10-35% of your daily calories as protein, or about 1.1-1.5 grams per kilogram of your body weight in protein if you work out regularly.^{[17]
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- To find how much protein you need, find your weight in kilograms, then multiply that by about 1.3. The resulting number is how many grams of protein you should eat per day.
- Foods rich in protein include eggs, fish, lean meat, low-fat dairy, nuts, and beans.

Section 8 of 8:

Summing It Up

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15-inch arms are above-average and a great fitness goal. According to CDC studies, the average arm circumference for an adult is 12–13 in (30–33 cm). That means that 15-inch arms are well above average and considered large.^{[18]
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Trustworthy Source

Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services

Go to source} That said, there’s no equation for how big your arms should be—that’s up for you to decide when you look in the mirror.
- To get bigger arms, perform arm and chest workouts like push-ups, dips, and curls. Perform them close to failure, but never strain yourself.
- Mix up your workouts to give your muscles variety, which helps build muscle more quickly.
- Incorporate more protein into your diet. Experts recommend getting 1.1-1.5 grams of protein per kilogram of your body weight if you work out regularly.^{[19]
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