What Is the Upper Arm Measurement for Malnutrition? Understanding MUAC

October 23, 2025 •

3 min read

According to UNICEF and WHO guidelines, a mid-upper arm circumference (MUAC) measurement is a simple and rapid tool for screening malnutrition, especially in children aged 6 to 59 months. This method uses a color-coded tape to quickly identify individuals who may require immediate nutritional support, making it an invaluable public health metric.

Quick Summary

The mid-upper arm circumference (MUAC) is a key screening tool for malnutrition, utilizing specific cutoff points to indicate nutritional status and severity in various age groups.

Key Points

MUAC Cutoffs Vary: Standard MUAC cutoff points are used to define moderate and severe malnutrition for different age groups, including children, adolescents, and adults.
Simple Screening Tool: The Mid-Upper Arm Circumference (MUAC) measurement is a simple, low-cost, and non-invasive method for rapidly assessing nutritional status.
Key Metric for Children: For children aged 6–59 months, a MUAC below 115mm indicates severe acute malnutrition, while 115mm to 125mm indicates moderate acute malnutrition.
Effective for Community Use: MUAC is particularly valuable for large-scale screenings in communities and emergency situations due to its simplicity and high portability.
Complementary to Other Methods: MUAC is often used in conjunction with other measures like Weight-for-Height Z-score (WHZ) to provide a more comprehensive nutritional diagnosis.
Predictor of Mortality: Studies have demonstrated that MUAC is an effective predictor of mortality risk in severely malnourished children, signaling the need for urgent intervention.
Accurate Technique is Key: Proper measurement technique, including finding the correct midpoint of the upper arm and applying the right tension, is essential for reliable results.

What is Mid-Upper Arm Circumference (MUAC)?

Mid-Upper Arm Circumference, or MUAC, is an anthropometric measurement used to assess the nutritional status of an individual by measuring the circumference of the mid-upper arm. It is a simple, cost-effective, and highly effective method, particularly useful for rapid screening in community-based programs and emergency settings where more complex equipment for measuring weight-for-height may not be available. The measurement primarily reflects the mass of muscle and subcutaneous fat in the upper arm, providing an indicator of overall body protein and energy reserves. A low MUAC indicates recent weight loss and is a strong predictor of mortality in malnourished children.

MUAC Cutoff Points for Malnutrition

The World Health Organization (WHO) and other international bodies have established standardized MUAC cutoff points to categorize nutritional status. These cutoffs vary by age group and are typically used in conjunction with other clinical signs like bilateral edema for a full diagnosis.

Pediatric Cutoffs (Children 6–59 Months)

For children between 6 and 59 months, MUAC is a critical indicator for identifying acute malnutrition:

Normal Nutritional Status: MUAC ≥ 125 mm
Moderate Acute Malnutrition (MAM): MUAC ≥ 115 mm to < 125 mm
Severe Acute Malnutrition (SAM): MUAC < 115 mm

Adult Cutoffs

MUAC is also an effective screening tool for adults, including pregnant women. Standard cutoffs exist for adolescents and adults to help detect underweight, particularly when Body Mass Index (BMI) is not feasible to measure.

Normal Nutritional Status: MUAC ≥ 220 mm
Moderate Acute Malnutrition (MAM): MUAC ≥ 185 mm to < 220 mm
Severe Acute Malnutrition (SAM): MUAC < 185 mm

Pregnant Women

Specific MUAC cutoffs are also recommended for pregnant and postpartum women to screen for undernutrition:

Normal Nutritional Status: MUAC ≥ 230 mm
Moderate Acute Malnutrition: MUAC ≥ 190 mm to < 230 mm
Severe Acute Malnutrition: MUAC < 190 mm

How to Measure MUAC Correctly

Accurate measurement is crucial to ensure reliable results. The process involves a few simple steps, often performed using a color-coded MUAC tape provided by organizations like UNICEF. You can find detailed steps and illustrations on how to measure MUAC correctly in the referenced document. Key steps include positioning the arm, locating the midpoint between the shoulder and elbow, wrapping the tape snugly but not tightly, and reading the measurement at the indicator.

MUAC vs. Weight-for-Height Z-Score (WHZ): A Comparison

MUAC and Weight-for-Height Z-Score (WHZ) are both used to assess malnutrition but have key differences in application and what they measure. They are not interchangeable and can identify different populations of malnourished individuals.


Feature	Mid-Upper Arm Circumference (MUAC)	Weight-for-Height Z-Score (WHZ)
Equipment	Simple, low-cost tape measure.	Requires accurate scales and stadiometers/length boards.
Ease of Use	Very easy and quick to administer, requires minimal training.	Requires more training and can be difficult for uncooperative or immobile individuals.
Portability	Highly portable, ideal for field and community screenings.	Less portable due to bulkier equipment.
Indicator	Reflects fat and muscle wasting, a strong predictor of mortality.	Reflects body weight relative to height, gold standard for diagnosis.
Age Bias	Absolute cutoffs can favor younger, smaller children over older ones.	Less age-biased for children within the 6-59 month range.
Complementarity	Identifies a specific group of children not always flagged by WHZ.	Standard diagnostic criterion, but can miss some cases identified by MUAC.

Factors Affecting MUAC and Its Interpretation

Factors such as age, gender, and underlying health conditions can influence MUAC measurements. For children aged 6 to 59 months, a single MUAC cutoff might be less accurate for younger or older children within this range compared to a middle age group. Some research suggests that age and gender-specific MUAC cutoffs could improve accuracy. MUAC is best used as a screening tool to prompt further clinical assessment rather than a sole diagnostic indicator.

The Role of MUAC in Nutritional Screening and Management

MUAC is a pivotal frontline screening tool for identifying individuals at high risk of malnutrition, particularly valuable in community-based management of acute malnutrition (CMAM) programs and emergency settings. Its simplicity allows non-specialized health workers to conduct widespread screenings. By identifying individuals with low MUAC, resources for therapeutic feeding and medical care can be prioritized for those at highest risk.

Conclusion

The upper arm measurement for malnutrition, or MUAC, is a simple but powerful tool for assessing nutritional status. Using specific cutoff points for different populations, it effectively screens for moderate or severe acute malnutrition. While its use requires considering factors like age and complementing it with other assessments, MUAC remains a critical tool in global public health for the early detection and management of malnutrition, especially in vulnerable groups.

Frequently Asked Questions

For children aged 6 to 59 months, a mid-upper arm circumference (MUAC) measurement of less than 115 mm indicates severe acute malnutrition (SAM) according to WHO guidelines.

To measure MUAC, find the midpoint of the person's non-dominant upper arm, between the shoulder and elbow. Wrap a non-stretch tape measure around the arm at this point, ensuring it is snug but not tight before reading the measurement.

Yes, MUAC is also used for adults. While widely used for children, a MUAC of < 23 cm or 185 mm is often used as a cutoff point for diagnosing malnutrition in adults, especially when BMI is difficult to measure.

Using MUAC alone can sometimes miss a significant proportion of malnourished individuals, especially when compared to other indicators like Weight-for-Height Z-score (WHZ). A single cutoff value can also have different accuracy depending on the child's age.

MUAC is a simpler, more rapid field screening tool that assesses muscle and fat wasting, while WHZ is a more detailed diagnostic measure comparing body weight to height. They are complementary tools and can identify different groups of malnourished children.

While the standard WHO cutoffs for children aged 6-59 months are not stratified by sex or smaller age groups, some research indicates that age and gender-specific cutoffs could improve screening accuracy.

A MUAC measurement of 120 mm falls within the 115 mm to < 125 mm range, indicating moderate acute malnutrition (MAM) in a child between 6 and 59 months.