Mid-Upper Arm Circumference
Mid-upper arm circumference (MUAC) is the distance around the upper arm at the midpoint between the tip of the shoulder (acromion) and the tip of the elbow (olecranon), measured with the arm relaxed at the side. It is a simple tape-measure marker of combined muscle mass and subcutaneous fat. In clinical settings MUAC is used as a screening indicator for under-nutrition in adults and children.
These percentiles are from US NHANES 2021-2023 (Fryar et al., NCHS 2025, n=5,850 adults), where obesity rates are among the world's highest, so norms skew higher than in most other countries. Read more on Wikipedia
How to Perform This Test (Protocol)
- Equipment
-
- Flexible non-stretch anthropometric tape with sub-cm graduations
- Protocol Steps
-
- Have the participant stand upright with the right arm relaxed at the side and the elbow flexed to 90 degrees, palm facing up.
- Locate the tip of the acromion process (point of the shoulder) and the tip of the olecranon process (point of the elbow).
- Measure the distance between these two points along the back of the upper arm. Mark the midpoint.
- Let the arm hang relaxed at the side, palm facing the thigh.
- Wrap the tape horizontally around the arm at the midpoint mark, snug but not compressing the skin.
- Record the circumference to the nearest 0.1 cm.
- Scoring
MUAC = circumference at the midpoint of the upper arm, measured in cm. Lower values reflect less arm tissue (muscle plus subcutaneous fat); higher values reflect more.
- Notes
NHANES uses the right arm; if the right arm is unsuitable (e.g. cast, mastectomy on that side) the left arm is used instead. Measurement is taken with the arm relaxed, not flexed.
Data source: Fryar et al. (NHANES 2021-2023) - Mid-upper arm circumference About this study
Reference population: US adults age 20 and over from NHANES 2021-2023, nationally representative; pregnant females excluded
Mid-Upper Arm Circumference Norms Chart by Age and Sex (cm)
| Age | Sex | Percentile | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| 20-29 | Male | 25.9 | 31.1 | 34.4 | 37.3 | 42.3 |
| Female | 24.3 | 27.6 | 30.9 | 35.1 | 43.3 | |
| 30-39 | Male | 28.1 | 32.2 | 34.9 | 38.0 | 43.2 |
| Female | 25.6 | 29.7 | 32.6 | 37.5 | 45.9 | |
| 40-49 | Male | 28.9 | 32.9 | 35.6 | 38.6 | 44.2 |
| Female | 25.5 | 29.2 | 32.5 | 36.6 | 43.9 | |
| 50-59 | Male | 28.4 | 31.7 | 34.5 | 38.1 | 44.4 |
| Female | 26.4 | 29.8 | 33.1 | 37.4 | 43.7 | |
| 60-69 | Male | 27.5 | 31.2 | 33.6 | 36.4 | 40.8 |
| Female | 25.3 | 29.0 | 32.2 | 35.9 | 42.2 | |
| 70-79 | Male | 27.4 | 30.4 | 33.3 | 35.9 | 40.1 |
| Female | 25.1 | 28.6 | 31.6 | 35.2 | 40.6 | |
| 80+ | Male | 26.1 | 29.1 | 31.2 | 34.1 | 38.5 |
| Female | 22.6 | 26.6 | 29.3 | 32.8 | 37.4 | |
What to expect by age group
Among US adults in their 30s, the middle 50% measure 32.2 to 38.0 cm for men and 29.7 to 37.5 cm for women. MUAC reflects combined muscle and subcutaneous fat. The male median is highest at 40-49 and the female at 50-59, and each is lower in every bracket after its peak. Both show their largest drop in the 80+ bracket.
| Age | Males | Females |
|---|---|---|
| 20-29 | 31.1 to 37.3 | 27.6 to 35.1 |
| 30-39 | 32.2 to 38.0 | 29.7 to 37.5 |
| 40-49 | 32.9 to 38.6 | 29.2 to 36.6 |
| 50-59 | 31.7 to 38.1 | 29.8 to 37.4 |
| 60-69 | 31.2 to 36.4 | 29.0 to 35.9 |
| 70-79 | 30.4 to 35.9 | 28.6 to 35.2 |
| 80+ | 29.1 to 34.1 | 26.6 to 32.8 |
Detailed Breakdowns
Select an age group and sex below for detailed percentile charts and distribution labels.
Frequently Asked Questions
What is mid-upper arm circumference?
Mid-upper arm circumference (MUAC) is the distance around the upper arm at the midpoint between the shoulder and the elbow, measured with the arm relaxed at the side. It is a simple tape-measure marker of combined arm muscle and subcutaneous fat.
How does MUAC change with age?
In this dataset male median MUAC rises from 34.4 cm at 20-29 to 35.6 cm at 40-49, then falls to 31.2 cm at 80+. Female medians rise from 30.9 cm at 20-29 to a peak of 33.1 cm at 50-59, then fall to 29.3 cm at 80+. MUAC is a tape measurement of the whole upper arm, so it tracks fat as well as muscle.
How is MUAC related to BMI or body fat?
MUAC partly overlaps with overall adiposity (people with higher BMI tend to have larger arm circumference) and partly reflects muscle mass, which BMI cannot capture. It complements BMI and body fat percentage as an arm-specific composition measure.
Why might my MUAC differ from these percentiles?
These percentiles are from US NHANES participants, who run higher on most body-composition measures than most global populations. Measurement technique matters: the protocol expects the arm relaxed at the side with the tape at the midpoint between the shoulder and elbow (not at the bicep peak or with the arm flexed).