The biceps brachii, usually referred to as the biceps, is a two-headed skeletal muscle that runs between the elbow and shoulder. Though not the largest of your arm muscles (that honor goes to the triceps), many people focus on getting bigger and stronger biceps at the gym.

Before upping your weights and adding an extra arm day to your routine, know that the average biceps size is influenced by your age, sex, and body mass index (BMI). Your BMI is based on your weight and height.

Wondering how you measure up? Let’s take a look at average biceps size, how to measure it, and how to make your biceps stronger.

The size of your biceps is influenced by a few factors. BMI tops the list. A person is more likely to have bigger arms if they have a higher BMI.

In terms of health and muscle, bigger arms because of a higher BMI isn’t generally considered an indicator of good health or strength.

BMI is a measure of body fat that’s calculated using your weight and height. Someone with a high BMI is usually considered overweight (though there are other methods that more accurately determine this). Having more fat around the arms will give you a larger circumference, even if your muscles are small.

If you’re curious about the average biceps size by height, that’s a little trickier.

Mid-upper arm circumference has been studied as a tool for estimating someone’s BMI in a situation when it’s not possible to measure a person’s height, but there doesn’t appear to be any research on how biceps size correlates to height.

Your arm circumference and biceps size change with age. The average biceps size varies between the sexes, too.

Here’s a look at the average circumference of the middle arm by age and sex based on information from the Centers for Disease Control and Prevention. Keep in mind this measurement also takes into account the amount of fat tissue as well as muscle.

Females

AgeAverage biceps size in inches
20–29 12.4
30–39 12.9
40–49 12.9
50–59 12.9
60–69 12.7
70–79 12.6
80+ 11.4

Males

AgeAverage biceps size in inches
20–29 13.3
30–39 13.8
40–49 13.9
50–59 13.5
60–69 13.4
70–79 12.9
80+ 12.1

There are two ways you can measure your biceps size: relaxed and flexed. Having someone else measure for you will be easier, especially when taking your relaxed measurement.

To measure your relaxed biceps:

  1. Stand up straight with your arms relaxed at your sides.
  2. Have someone else hold soft measuring tape around your biceps, which is the midpoint between the tip of your shoulder and tip of your elbow.

To measure your flexed biceps:

  1. Sit at a table and rest your arm on the tabletop.
  2. Make a fist. Curl your forearm up toward your shoulder, as if doing a bicep curl, flexing as hard as you can.
  3. Hold the end of a soft measuring tape over the highest point of your biceps and around it so both ends meet to give you your measurement.

Weightlifting is the first thing that comes to mind when you think of building muscle, and that’s definitely part of increasing your biceps size.

When you lift weights, your muscle experiences minor trauma. This causes the cells in your muscle fibers to activate and attempt to repair the damage. The cells join together, increasing the size and strength of your muscle fibers.

Your diet also plays a role in building muscle. Increasing your protein intake is important, because protein helps repair and build lean muscle tissue. Protein also helps keep you full longer, making it easier to avoid overeating.

The Mayo Clinic recommends eating 15 to 25 grams of protein at each meal or snack while keeping within your total calorie needs.

Here are some examples of foods that help you build lean muscle:

  • poultry
  • beef
  • fish
  • eggs
  • milk
  • yogurt
  • beans
  • nuts

Now that you know what to eat, start building muscle with these exercises:

There are a few factors that determine the average biceps size. While some may be out of your control, like your age and sex, you can control things like diet and exercise.

A healthy diet with ample protein as well as a weightlifting regimen can help you get stronger biceps.