How Big Are 15 Inch Arms?

Arm Size Calculator & Circumference Statistics

By: Jeremy Fox, CNC, CPTPublished: May 19, 2022

Strong and muscular arms are a key indicator of physical fitness and strength. Let’s face it, everyone loves an action hero with big guns.

That’s why arm curls are one of the most popular exercises at the gym. So how do you know if your arms are average or exceptional?

Well, upper arm circumference is a yardstick by which many measure their progress. And 15 inch arms are a common benchmark.

But are 15 inch arms good or not? Read on to find out!

15 Inch Arms

What Are 15 Inch Arms?

Arm size is a circumference measurement of the mid-upper arm. So “15 inch arms” are 15 inches (38.1 cm) around at the widest part of the bicep and tricep.

How to Measure Your Arms

Before getting into arm sizes, make sure you’ve measured your arm accurately. Arm size is measured using a flexible tape such as a tailor’s tape.

First, raise one arm parallel to the floor and drape the end with the number “1” over the front of your bicep. Then wrap the other end of the tape around the widest part of your arm until the numbers overlap the end.

How To Measure Arms

The number that intersects the end of the tape is your arm size. As you can see in the image above, bodybuilders measure their arms flexed.

Tips: Do not pull the tape too tight or your arm will appear smaller. Also do not wrap the tape at an angle or your arm will appear bigger.

Are 15 Inch Arms Big?

15 inch flexed arms are a decent size. Anything over 14.6 inches is above average for men. And over 13.4 inches is above average for women.

However, you might want to be more than “above average”. And 15 inch arms could be on the small side if you have been working out for a while or have a large frame.

Whether your arms look big on your body depends on your age, height, weight, and body composition.

15 Inch Arms by Age

Your age is one of the most obvious factors that influence your arm size. Because we all start with skinny arms as children and grow through our teenage years.

Once you reach adulthood, your arm growth slows down. Although most people’s arms get a little bigger through their 20s and 30s.

At some point in your 40s, however, your arms might start to gradually get smaller in size. This decline is due to the drop in hormones as well as a decrease in physical activity.

Table 1. Average Arm Size By Age For Men & Women (Unflexed)

Age Men Women
20-29 13.4 inches (34.1 cm) 12.4 inches (31.5 cm)
30-39 14.1 inches (35.9 cm) 12.9 inches (32.8 cm)
40-49 14.0 inches (35.6 cm) 13.1 inches (33.3 cm)
50-59 13.7 inches (34.8 cm) 12.9 inches (32.8 cm)
60-69 13.5 inches (34.4 cm) 12.8 inches (32.4 cm)
70-79 13.1 inches (33.2 cm) 12.6 inches (32 cm)
80+ 12.1 inches (30.8 cm) 11.7 inches (29.6 cm)

The data in the chart above comes from the National Center for Health Statistics in the US. But it’s important to realize that these measurements are taken with the arm relaxed or unflexed.

Arm Size Flexed vs Unflexed

When you flex your bicep, your arm increases in size roughly 5-10%. So a 13.5” unflexed arm is generally about 14.5” flexed.

And, since you probably measured your arm flexed, it’s vital to adjust the data from the previous table to compare apples to apples. Below is the revised arm size data based on the estimated size increase with a flexed bicep.

Table 2. Average Arm Size By Age For Men & Women (Flexed)

Age Men Women
20-29 14.4 inches (36.6 cm) 13.3 inches (33.7 cm)
30-39 15.2 inches (38.6 cm) 13.9 inches (35.3 cm)
40-49 15.1 inches (38.4 cm) 14.1 inches (35.8 cm)
50-59 14.7 inches (37.3 cm) 13.9 inches (35.3 cm)
60-69 14.6 inches (37.1 cm) 13.7 inches (34.8 cm)
70-79 14.1 inches (35.8 cm) 13.5 inches (34.3 cm)
80+ 13 inches (33 cm) 12.5 inches (31.8 cm)

In Table 2, you can see that the average man has around 14½ inch arms. Therefore, 15 inch arms are slightly above average.

For women, the average arm size is a little smaller at 13½ inches. And 15 inch arms would be well above average.

To put this arm size data in perspective, it helps to look at it in terms of percentiles. This shows you how likely you are to have arms of a certain size.

Table 3. Arm Size Percentiles For Men & Women (Flexed)

Percentile Men Women
5th 11.9 inches (30.3 cm) 10.5 inches (26.8 cm)
10th 12.6 inches (31.9 cm) 11.1 inches (28.1 cm)
15th 12.9 inches (32.8 cm) 11.4 inches (28.9 cm)
25th 13.4 inches (34.1 cm) 12 inches (30.6 cm)
50th 14.6 inches (37.1cm) 13.4 inches (34.1 cm)
75th 16 inches (40.7cm) 15.2 inches (38.5 cm)
85th 16.9 inches (42.9 cm) 16.2 inches (41.2 cm)
90th 17.4 inches (44.2 cm) 17.2 inches (43.7 cm)
95th 18.4 inches (46.7 cm) 18.2 inches (46.1 cm)

Now you can see that a man with 15 inch arms is in the 55th percentile. In other words, your biceps are bigger than average but smaller than 9 out of 20 men.

And for women, 15 inch arms puts you in the 75th percentile. That means a female with 15 inch arms would have bigger biceps than about 3 out of 4 women.

But you probably aren’t having a flex off with an 80-year-old. So here are some charts to help you visualize how big 15 inch arms are based on a normal distribution of arm sizes for people ages 20-59.

15 Inch Arms Normal Distribution Men
15 Inch Arms Normal Distribution Women

15 Inch Arms by Weight

How much you weigh also factors into how big your arms look on your body. For example, 15 inch arms look much bigger on a 150lb guy than a 250lb guy.

In other words, the heavier you are, the bigger your arms need to be to look impressive. Obviously, you want that weight to be muscle, not fat. I’ll get into that in a minute.

15 Inch Arms by Height

Finally, your height also plays a role in how big your arms look.

To illustrate, picture a 5’6” person standing next to a 6’6” person. If they both have 15 inch arms, the short guy’s arms will look much bigger.

So the taller you are, the bigger your arms need to be to look impressive.

Arm Size Calculator

Height, weight, and age make it difficult to know if your arms are considered big. Fortunately, there are equations to predict average arm size based on these variables.

I created a simple calculator that shows you if your arms are big or small for your demographic.  

arm size calculator

Enter the information below to see if your arms are bigger than other people your age and size.

15 Inch Arms by Body Fat Percentage

There are a couple of other factors to consider that are not included in the arms size equation. One of them is your body fat percentage.

Basically, having more muscle and less fat makes your arms appear larger. The reason is that you can see the separations between your arm and shoulder. And sometimes even the muscle striations and veins.

In addition, being leaner makes your arms look bigger compared to your arm joints (wrist, elbow) and your waist. These are the proportions considered in the Greek God Body and determine if you have an aesthetic physique.

As an example, below is what I look like when bulking vs cutting. My arms are actually about 16 inches in both pictures, but they clearly look bigger when I’m lean!

And the same principle holds true for 15 inch arms.

16 Inch Arms Bulk vs Cut

I weighed 198lbs on the left and 171lbs on the right and I’m 5’9″ tall. It goes to show that your arms look bigger when you’re lean. I should also note that I had an arm pump in both pictures.

Arm Size Pump vs No Pump

It’s also important to realize that increased blood flow to your arms while working out makes them swell up in size – aka the pump. So measuring your arms right after arm exercises can add 0.5-1″.

For accuracy, it’s best to measure your arms without a pump. That way, you see your true arm size and not just how much volume you did on bicep curls.

Of course, it is fun to measure your arms with a huge pump occasionally to see how big you can get them! Just take the inflated measurement with a grain of salt and know that’s not how big your arms normally are.

How Long Does A Pump Last & 10 Ways To Prolong Your Pump

How To Build 15 Inch Arms

Building a big set of arms takes more than just repping out sets of bicep curls. Instead, you need a well-rounded plan, including nutrition, workouts, and a few proven supplements.


Believe it or not, how you eat is more important than how you lift when building muscle. You won’t progress very far in the gym if you don’t give your body what it needs to grow.

First, you need to create a calorie surplus to gain muscle consistently. That means you eat more calories than you burn each day.

Calorie Surplus For Bulking II

Next, you must eat enough protein to provide your arms with the building blocks to grow new muscle tissue. And don’t listen to that 1 gram of protein per pound of bodyweight bro science!

Your lean mass, activity level, and fitness goal dictate how much protein you need.

Calculate Your Grams of Protein Per Day

Some other nutrition advice I have is to eat mostly clean foods. Skip the junk and steer towards whole, natural foods to get the most quality gains.

Also, tap into nutrient timing to unlock the last 10% of potential arm gains. That means getting most of your carbs and calories around your workout.

bodybuilding meal plan

Custom Meal Plan

Get a personalized meal plan designed specifically for your body and lifestyle. Including custom recipes formulated to fit your macros and calories – no counting required!

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To build big arms, you need to train your whole body. That may sound counterintuitive, but compound exercises like squats and deadlifts boost muscle-building hormones that help you build big arms.

As for your biceps, they are made up of a long head and a short head. The inner short head creates size and thickness, while the outer long head adds to the peak. So include a variety of exercises to hit both bicep heads.

Hammer Curls vs Bicep Curls For Peak & Width

15 Inch Arms Outer Bicep Workout

Also, don’t forget to train your triceps because they make up approximately 2/3 of the area of your arm! Therefore, big triceps make it easier to build 15 inch arms.


As a word of caution, do not expect supplements to miraculously grow your arms in days or weeks. Instead, supplements are only an add-on to proper diet and exercise that may give you a small boost.

In addition, there are a lot of snake oil supplements that cost a lot of money and don’t deliver results. Here are some proven muscle-building supplements that can help you build bigger arms.

How Long Does It Take to Get 15 Inch Arms?

The time it takes to get 15 inch arms depends on your starting point. For example, if you’re relatively new to training and already have 14 inch arms, you could reach 15 inches in a few months.

On the other hand, it could take you a year or more if you’ve been lifting for a while and need to gain more than an inch of arm size. But don’t get discouraged because 15 inch arms are easily attainable for most people.

How To Build Your Arms Faster

Now you know how 15 inch arms measure up. Once you get there, you’ll probably feel like building 16 inch arms or even 17 inch arms!

If you want to grow your arms in weeks instead of months, you must start with a dialed-in muscle gain meal plan. And you can get a personalized, easy-to-follow nutrition plan right here.

Click the image or button below to learn more about Custom Meal Plans for Muscle Growth.

With this information, you’re well on your way to building an impressive pair of arms. And if you liked this article, make sure you check out some of my other helpful content below!

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