Average Bicep Size by Age, Height, and Gender (With Charts)

What the data actually says

Most of the arm size data floating around the internet comes from one source: the CDC's National Health and Nutrition Examination Survey (NHANES). This is a rolling study that has been measuring Americans since the 1960s. They measure everything from cholesterol to, yes, arm circumference.

The catch? NHANES measures mid-upper-arm circumference on relaxed, unflexed arms. So the numbers you see are not flexed bicep measurements. They include bone, fat, and whatever muscle happens to be there. Keep that in mind as we go through this.

Average arm size for men by age

These numbers come from the most recent NHANES data available. All measurements are relaxed, unflexed, at the midpoint between the shoulder and elbow.

The peak is in the 40-49 range, which makes sense. By 40, most men have accumulated some body fat on their arms (whether they wanted to or not), which increases circumference. The actual lean muscle mass underneath probably peaked somewhere in the late 20s to mid-30s for the average untrained person.

Average arm size for women by age

Women's averages are about an inch smaller across the board, which is exactly what you would expect given differences in testosterone levels and total muscle mass. The consistency across ages 30-59 is interesting. It suggests that whatever muscle women lose in those decades is roughly offset by fat gain.

How height affects arm size

NHANES does not break out arm circumference by height directly, but we can make reasonable inferences. Taller people have longer bones, which means longer muscle bellies, which means more total muscle mass at the same relative development level.

A rough guideline for trained males:

These are flexed, cold (no pump) measurements on someone with a reasonable body fat percentage (12-18%). If you are at 25% body fat, add an inch and subtract your self-respect. Kidding. Sort of.

The body fat problem

This is where arm size discussions go off the rails. A 16-inch arm at 12% body fat looks completely different from a 16-inch arm at 25% body fat. The lean arm has visible separation between the bicep and tricep, a vein or two running down the front, and a noticeable peak when flexed. The high-body-fat arm looks like a smooth cylinder.

Here is a rough idea of how much fat contributes to arm circumference at various body fat levels for a male with a 16-inch measured arm:

This is why I tell people to stop obsessing over the tape measure number and start paying attention to the mirror. A lean 15-inch arm looks bigger than a fat 16.5-inch arm in every real-world scenario. In a t-shirt, at the beach, wherever it matters.

Trained vs. untrained: a different comparison

If you lift weights, comparing yourself to NHANES data is kind of pointless. Those averages include everyone: office workers, couch surfers, and 80-year-olds who have not picked up anything heavier than a TV remote in 30 years.

A better comparison for lifters:

For women, subtract about 2-3 inches across the board. A woman with 14-inch flexed arms who lifts is legitimately impressive and probably has years of serious training under her belt.

These numbers assume reasonable body fat levels and natural training. If you are on gear, throw the chart out the window.

Realistic growth expectations

This is the part where I have to manage your expectations, and I am sorry in advance.

Year one of serious training: You might gain 1-2 inches on your arms. This is the golden era. Enjoy it. Newbie gains are real and they are spectacular. A skinny guy starting at 12-inch arms can realistically hit 13.5-14 inches in his first year if he trains hard and eats enough.

Year two: Maybe half an inch to an inch. Progress slows down. This is where most people start program hopping because they think something is wrong. Nothing is wrong. You are just past the easy part.

Year three and beyond: A quarter to half an inch per year is good progress. Seriously. If you added half an inch to your arms every year from year three to year ten, you would gain 3.5 inches. That is the difference between 14.5-inch arms and 18-inch arms. It just takes a long time.

A study by Wernbom et al. (2007) looked at muscle cross-sectional area gains and found that untrained individuals could increase bicep size by about 0.1-0.5% per day in the early weeks of training. That rate drops off fast. By the time you have been training for a few years, gains are measured in fractions of a percent per month.

Frame size matters more than people admit

Two guys can have identical arm circumference and look completely different. A guy with narrow shoulders, thin wrists, and small joints will have arms that look huge at 15.5 inches. A big-framed guy with thick wrists and broad shoulders might need 17 inches before his arms look proportionate.

Your wrist circumference is a decent proxy for frame size:

Small-framed lifters: your arms will look impressive at lower absolute measurements, but you have less room for total growth. Large-framed lifters: you can potentially build bigger arms in absolute terms, but they need to be bigger to look big on your frame.

Neither is better or worse. It is just genetics. Play the hand you were dealt.

How ethnicity and body type play into these numbers

Something most articles leave out: these NHANES averages are population-wide. They do not account for differences in body composition tendencies across ethnic groups, somatotypes, or regional populations.

People of West African descent, for example, tend to carry more lean mass in the upper body relative to body weight. Conversely, people of East Asian descent may have lighter bone structures on average. These are population-level trends with massive individual variation, so do not use them to set your personal expectations. Your genetics are your genetics, regardless of what any demographic average says.

What actually matters more than ethnicity is your individual body type. Mesomorphic body types (naturally broader shoulders, thicker joints, responds well to resistance training) will generally reach higher arm measurements faster than ectomorphic body types (narrow frame, thin wrists, harder time gaining weight). But ectomorphs often look more impressive at lower absolute numbers because the muscle they do build stands out more against their frame.

I have coached guys with 6-inch wrists who look jacked at 14.5-inch arms and guys with 8-inch wrists who look underwhelming at 16 inches. The frame changes everything.

What the averages do not tell you

Here is what bugs me about arm size charts. They reduce a three-dimensional, visually complex body part to a single number. That number tells you nothing about:

• •Muscle shape and insertions. A guy with high bicep insertions might have a dramatic peak that makes his 15-inch arm look like a mountain. A guy with low insertions might have a full, round arm that measures 16 inches but looks thicker rather than peaked. Both are great. Neither is captured by a circumference measurement.

• •Tricep development. Two guys can have identical arm measurements, but if one has well-developed triceps (especially the lateral head that creates that horseshoe shape), his arm will look significantly more muscular than the guy whose measurement comes mostly from bicep mass.

• •Forearm-to-upper-arm ratio. A pair of 15-inch upper arms with 13-inch forearms looks proportionate and athletic. The same upper arms with 10.5-inch forearms look top-heavy and unfinished. The upper arm number alone misses this.

• •Leanness and definition. I keep coming back to this because it matters so much. The difference between a defined arm and a smooth arm at the same measurement is the difference between someone asking if you work out and nobody noticing at all.

When to stop comparing

I will be blunt: if you have been training for more than two years and you are still checking average bicep size charts every week, the problem is not your arms. The problem is your relationship with your body.

Here is what actually matters:

• •Are your arms bigger than they were six months ago?
• •Are you getting stronger on your arm exercises?
• •Do you like how you look in the mirror?

If the answer to those questions is yes, your arms are the right size. The charts are just data. They cannot tell you whether you look good, feel good, or are making progress relative to your own starting point.

Use these averages the way they were intended: as rough context. Then close the browser tab and go train.