Quick answer: the average bicep size is about 13.7 inches (34.7 cm) for men and 13.0 inches (32.9 cm) for women, measured relaxed (U.S. adults 20+, NHANES 2021–2023). Flexed, the average man measures about 14.1 inches (35.8 cm).
Bicep Size Chart
Each figure below is the same 5 ft 10 in, 176 lb man with a different upper-arm size, from 12 to 17 inches. Under each one you can see where that size ranks among U.S. men, both relaxed (general population) and flexed (U.S. Army).
| Arm size | Men, relaxed | Men, flexed | Women, relaxed | Women, flexed |
|---|---|---|---|---|
| 12 in (30.5 cm) | 17th | 6th | 36th | 50th |
| 13 in (33.0 cm) | 37th | 21th | 55th | 80th |
| 14 in (35.6 cm) | 60th | 48th | 71th | 95th |
| 15 in (38.1 cm) | 78th | 76th | 82th | 99th |
| 16 in (40.6 cm) | 89th | 91th | 90th | 99th |
| 17 in (43.2 cm) | 95th | 98th | 95th | 99th |
| 18 in (45.7 cm) | 98th | 99th | 98th | 99th |
The same tape reading means very different things depending on how you measured. A 14 inch arm is above average relaxed but only average flexed, because flexing adds roughly half an inch to an inch on most people and more on trained lifters.
Average Bicep Size for Men
The average relaxed arm for U.S. men aged 20 and over is 13.7 inches (34.7 cm), and the median is 13.5 inches. The middle half of men fall between 12.4 and 14.8 inches. Flexed, the average among U.S. Army men is 14.1 inches (35.8 cm).
| Percentile | Men, relaxed | Men, flexed | Women, relaxed* | Women, flexed |
|---|---|---|---|---|
| 5th | 10.9 in (27.7 cm) | 11.9 in (30.3 cm) | 10.0 in | 10.1 in |
| 25th | 12.4 in (31.5 cm) | 13.2 in (33.5 cm) | 11.4 in | 11.2 in |
| 50th | 13.5 in (34.4 cm) | 14.1 in (35.7 cm) | 12.7 in | 12.0 in |
| 75th | 14.8 in (37.5 cm) | 15.0 in (38.0 cm) | 14.3 in | 12.8 in |
| 95th | 16.9 in (42.9 cm) | 16.5 in (41.8 cm) | 17.0 in | 14.0 in |
*Women’s overall relaxed percentiles are averaged from the NHANES age-group tables. Flexed data come from soldiers, who are younger and leaner than the general population.
Notice that the relaxed 95th percentile (16.9 in) is higher than the flexed 95th (16.5 in). That is not a mistake: the general population includes many people whose arm size comes from body fat, while soldiers are leaner. A big relaxed arm is not always a muscular one.
Average Bicep Size for Women
The average relaxed upper arm for U.S. women aged 20 and over is 13.0 inches (32.9 cm), with a median of about 12.7 inches. Among U.S. Army women, who are leaner, the average flexed arm is about 12.0 inches (30.6 cm), and the middle half measure 11.2–12.8 inches.
Women store a larger share of arm size as fat, especially at the back of the arm, so relaxed arm size in women tracks body weight more closely than muscle. If your goal is toned arms, a stable or slightly smaller relaxed measurement with more strength is often real progress. Women carry more fat on the hips and thighs too; see the body fat percentage chart for where your level sits.
Average Bicep Size by Age
Arm size rises through early adulthood, peaks in the 40s for men and the 50s for women, then falls as muscle is lost with age. These are relaxed measurements from the latest NHANES survey (2021–2023), in inches with centimeters in brackets.
| Age | Men, median | Men, middle half | Women, median | Women, middle half |
|---|---|---|---|---|
| 20-29 | 13.5 in (34.4) | 12.2–14.7 in | 12.2 in (30.9) | 10.9–13.8 in |
| 30-39 | 13.7 in (34.9) | 12.7–15.0 in | 12.8 in (32.6) | 11.7–14.8 in |
| 40-49 | 14.0 in (35.6) | 13.0–15.2 in | 12.8 in (32.5) | 11.5–14.4 in |
| 50-59 | 13.6 in (34.5) | 12.5–15.0 in | 13.0 in (33.1) | 11.7–14.7 in |
| 60-69 | 13.2 in (33.6) | 12.3–14.3 in | 12.7 in (32.2) | 11.4–14.1 in |
| 70-79 | 13.1 in (33.3) | 12.0–14.1 in | 12.4 in (31.6) | 11.3–13.9 in |
| 80+ | 12.3 in (31.2) | 11.5–13.4 in | 11.5 in (29.3) | 10.5–12.9 in |
After 60, holding on to arm size is a sign of keeping muscle, which matters for strength and independence. Resistance training at any age slows that loss.
Average Bicep Size by Height
Taller men tend to have slightly bigger arms, but the effect is small: about two-thirds of an inch from 5 ft 4 to 6 ft. Body weight and training matter far more than height.
| Height | Men measured | Median | Middle half |
|---|---|---|---|
| 5 ft 2–3 in | 86 | 13.5 in | 12.6–14.2 in |
| 5 ft 4–5 in | 402 | 13.7 in | 13.0–14.6 in |
| 5 ft 6–7 in | 899 | 13.8 in | 13.0–14.7 in |
| 5 ft 8–9 in | 1154 | 14.1 in | 13.2–14.9 in |
| 5 ft 10–11 in | 939 | 14.3 in | 13.4–15.2 in |
| 6 ft 0–1 in | 428 | 14.4 in | 13.4–15.2 in |
| 6 ft 2–3 in | 124 | 14.8 in | 13.6–16.1 in |
If you want a target scaled to your frame, wrist size is a better guide than height. Check your frame with the body frame size calculator.
Relaxed vs. Flexed Bicep Size
Relaxed arm circumference is measured with the arm hanging loose, halfway between the shoulder and elbow. It is what doctors and health surveys use, partly because it tracks nutrition and muscle loss in older adults.
Flexed bicep size is measured with the arm raised and the bicep contracted, around the highest point. It is what lifters quote. The difference between the two is usually 0.5 to 1.5 inches and grows with muscle size.
A third version, the “cold” measurement, is simply a flexed arm measured before a workout, without a pump. Pumped arms can measure a quarter to half an inch bigger for an hour after training.
How to Measure Your Bicep Size
- Find the midpoint. Stand with your arm hanging at your side. Find the bony tip of the shoulder and the point of the elbow, and mark halfway between them on the back of the arm.
- Measure relaxed. Wrap a soft tape around the arm at the mark, level and snug but not squeezing. Read the number after a normal breath. This matches how NHANES measures.
- Measure flexed (optional). Raise the arm to shoulder height, bend the elbow and squeeze the bicep hard. Wrap the tape around the highest point of the bicep and the matching point of the triceps.
- Repeat and record. Measure each arm twice and use the average. Measure at the same time of day, before training, so a pump does not inflate the number.
See all the tape positions for bust, waist, hips and more in our body measurements guide.
What Decides Bicep Size, and How to Grow It
Muscle, fat and frame. Your arm circumference is the sum of bone, the biceps and triceps (the triceps make up about two thirds of upper-arm muscle) and the fat around them. Training the triceps adds more to the tape than training the biceps alone.
Training. Most research on muscle growth points to the same basics: work each muscle with roughly 10 or more hard sets a week, take sets close to failure, and add weight or reps over time. Compound lifts such as rows, chin-ups and presses help, and direct curls and triceps work add extra volume.
Body fat. Arms often measure bigger during a bulk and smaller during a cut even when muscle barely changes. To see what your arms would look like on a different body, try the 3D body visualizer.
Bicep Size FAQ
What is the average bicep size for men?
The average relaxed upper-arm (bicep) circumference for U.S. men aged 20 and over is about 13.7 inches (34.7 cm), with a median of 13.5 inches (34.4 cm), according to NHANES 2021–2023. Flexed, the average for U.S. Army men is about 14.1 inches (35.8 cm).
What is the average bicep size for women?
The average relaxed upper-arm circumference for U.S. women aged 20 and over is about 13.0 inches (32.9 cm). Flexed, the average for U.S. Army women is about 12.0 inches (30.6 cm), lower because soldiers carry less body fat on the arm than the general population.
Is a 14 inch bicep good?
A 14 inch arm is right around average for a man: about the 60th percentile relaxed and the 48th percentile flexed. For a woman, a 14 inch relaxed arm is above average (about the 71th percentile).
Is a 15 inch bicep big?
A 15 inch flexed arm is above average for a man, bigger than about 76% of U.S. Army men. On a lean person it looks clearly muscular; on someone with more body fat it may look average.
Are 16 inch arms big?
Yes. A 16 inch flexed arm is bigger than about 91% of U.S. Army men. At a low body fat it usually takes years of consistent training to reach.
Is bicep size measured flexed or relaxed?
Health surveys such as NHANES measure the relaxed arm, hanging at the side, halfway between the shoulder and elbow. Gyms and lifters usually measure the flexed arm at the peak of the bicep. Always compare a flexed number with flexed data and a relaxed number with relaxed data.
Does bicep size change with age?
In NHANES, median relaxed arm size for men rises from 34.4 cm in the 20s to 35.6 cm in the 40s, then falls to 31.2 cm after 80 as muscle is lost. Women follow a similar pattern, peaking in their 50s.
How fast can you grow your biceps?
Beginners who train consistently often add about 1 to 2 inches in the first year, much of it from muscle and some from body fat if they gain weight. Progress slows after that. Training the arms with enough weekly sets, progressing the load and eating enough protein matter most.
Sources
- Fryar CD, et al. Anthropometric Reference Data for Children and Adults: United States, 2021–2023. National Center for Health Statistics, 2025. doi:10.15620/cdc/174595
- Gordon CC, et al. 2012 Anthropometric Survey of U.S. Army Personnel: Methods and Summary Statistics (ANSUR II). NATICK/TR-15/007, 2014.
- National Center for Health Statistics. NHANES Anthropometry Procedures Manual.
- Schoenfeld BJ, Ogborn D, Krieger JW. Dose-response relationship between weekly resistance training volume and increases in muscle mass. Journal of Sports Sciences. 2017;35(11):1073–1082.
Percentiles between the published 5th, 25th, 50th, 75th and 95th points are interpolated. Flexed reference data come from U.S. Army personnel. For general information only.