What tool is used to measure MUAC?: Understanding Mid-Upper Arm Circumference Tapes

October 23, 2025 •

5 min read

According to the World Health Organization, malnutrition is a leading cause of childhood mortality globally, underscoring the need for quick and accurate assessment tools. This is why knowing what tool is used to measure MUAC? is crucial for health workers and caregivers, as a simple tape measure provides a reliable indicator of nutritional status.

Quick Summary

A specialized, color-coded MUAC tape is used for measuring mid-upper arm circumference. It is an inexpensive, portable, and effective tool for rapidly screening children and adults for malnutrition, particularly in public health and emergency settings.

Key Points

Specialized Tape: A dedicated MUAC tape, often color-coded and non-stretch, is the specific tool used for mid-upper arm circumference measurement.
Easy Interpretation: For children, color-coded tapes allow health workers to quickly identify a child's nutritional status as normal (green), moderately malnourished (yellow), or severely malnourished (red).
Rapid Screening: MUAC measurement is an ideal method for rapid nutritional screening in public health and emergency settings due to its speed, portability, and low cost.
Accurate Technique is Crucial: Proper technique, including correctly identifying the midpoint of the arm and ensuring the right tape tension, is essential for obtaining an accurate measurement.
Useful for Various Groups: While famously used for young children, MUAC is also valuable for assessing malnutrition in adults, pregnant women, and the elderly.
Complementary Tool: MUAC is often used alongside or as an alternative to other nutritional indicators like BMI or weight-for-height z-scores, each with its own advantages and disadvantages.
Predictor of Mortality: A low MUAC measurement is a significant predictor of mortality risk, especially in children, making it a critical triage tool.

What is Mid-Upper Arm Circumference (MUAC)?

Mid-Upper Arm Circumference, or MUAC, is a measurement of the circumference of the upper arm at its midpoint. It is a valuable and rapid indicator of an individual's nutritional status, specifically reflecting the body's muscle and fat reserves. In malnourished individuals, these reserves are depleted, causing the MUAC measurement to fall below established thresholds. Due to its simplicity, speed, and low cost, MUAC is widely used in resource-limited settings for the early detection and triage of malnutrition.

The Purpose of MUAC Measurement

The primary purpose of measuring MUAC is to screen for and assess malnutrition, particularly wasting or acute malnutrition. It is a powerful predictive tool for mortality risk in children and adults. For children aged 6 to 59 months, MUAC is especially useful because its value remains relatively stable during this period in well-nourished children, making it an age-independent screening tool. Beyond emergency health settings, MUAC can be a practical tool for monitoring nutritional changes over time in various clinical and community health programs.

The MUAC Tape: A Specialized Tool

What tool is used to measure MUAC?

The tool used to measure MUAC is a specialized measuring tape, commonly referred to as a MUAC tape. Unlike a standard measuring tape, MUAC tapes are specifically designed for this purpose and are often made from non-tear, stretch-resistant material to ensure accuracy. They are graduated in millimeters and often feature color-coded segments to allow for quick and easy interpretation of results, even by field workers with minimal training.

Design and Features of a MUAC Tape

Material: Made from durable, non-stretch synthetic material like plasticized paper to prevent measurement errors.
Color-Coding: Tapes for children typically have color-coded sections: green (normal), yellow (moderate malnutrition), and red (severe malnutrition). Tapes for adults may or may not be color-coded, as there is less international standardization for adult cut-offs.
Graduations: Marked in millimeters for precise measurement, with the reading typically taken through a window on the tape.
Mechanism: Features an interlocking or insertion design to create a snug but not-too-tight fit around the arm.

How to Measure MUAC Correctly

Preparation: Ask the person to relax their left arm (if they are right-handed) and remove any clothing that covers the arm.
Locate Midpoint: Bend the arm at a 90-degree angle to find the tip of the shoulder (acromion process) and the tip of the elbow (olecranon process). Using the tape, measure the distance between these two points and mark the midpoint with a pen or finger.
Wrap the Tape: With the arm hanging loosely by the person's side, wrap the MUAC tape around the arm at the marked midpoint.
Ensure Proper Tension: Pull the tape so it is snug but not pinching the skin. The tape should be flat against the arm.
Read the Measurement: Read the measurement in the window where the arrows point inward. Record the value and corresponding color.

MUAC vs. Other Nutritional Assessment Tools


Feature	MUAC Tape	Body Mass Index (BMI)	Weight-for-Height Z-score (WHZ)
Tool Required	Specialized, color-coded tape	Scale and stadiometer (or measuring board)	Scale and stadiometer, plus software
Skill Level	Minimal training required for community screening	Requires more careful measurement of height and weight	Requires accurate measurements and calculations
Cost & Portability	Very low cost and highly portable; ideal for field use	Equipment can be expensive and difficult to transport	Dependent on equipment; not as field-friendly
Primary Use	Rapid screening for acute malnutrition (wasting)	Screening for both overweight/obesity and underweight	Highly sensitive indicator for diagnosing acute malnutrition
Populations	Children (6-59 mos), adults, pregnant/lactating women	Adults, adolescents, children	Children, especially under 5 years old
Sensitivity	Can be low in some cases, with studies suggesting adjusted cut-offs for higher sensitivity	Correlates well with overall body composition but cannot differentiate fat/muscle mass	Considered a gold standard but requires more resources

The Broader Impact of MUAC in Public Health

MUAC measurements are a cornerstone of many public health programs, especially those dealing with emergency situations, including food crises and natural disasters. Because the tool is simple and portable, it allows aid workers to quickly screen a large number of people in a short amount of time. A MUAC measurement can help prioritize the most vulnerable individuals—typically children with severe acute malnutrition—for immediate, life-saving nutritional treatment, often with ready-to-use therapeutic food (RUTF).

Evolving Use and Standardization

While MUAC has been used for decades, its application and interpretation are continuously refined. For example, ongoing research and meta-analyses seek to optimize cut-off values for different age groups and genders to improve diagnostic accuracy, particularly in comparison to other metrics like WHZ. Efforts are also underway to standardize MUAC tape designs globally to eliminate systematic bias that can arise from variations in material and thickness. This ongoing work highlights the importance of this simple tool and the commitment to improving its effectiveness in diagnosing malnutrition.

Conclusion

In conclusion, the tool used to measure MUAC is a specialized, non-stretch MUAC tape. This simple yet highly effective device is a critical component of nutritional screening in both clinical and community settings, particularly for the rapid identification of acute malnutrition in vulnerable populations. Its advantages lie in its portability, low cost, and ease of use, making it an essential instrument for public health interventions worldwide. As nutritional science and understanding evolve, the refinement of MUAC tape design and cut-off points will continue to enhance its diagnostic accuracy, further solidifying its role in the global fight against malnutrition. Organizations like UNICEF provide comprehensive resources and materials to support the effective use of MUAC tapes in the field.

MUAC in Specific Populations

Children: MUAC is widely used for children between 6 and 59 months, as it is a strong predictor of mortality risk.
Pregnant and Lactating Women: A MUAC measurement can help identify at-risk mothers, allowing for intervention and support to improve maternal and fetal health.
Adults: MUAC can also be used for adult nutritional assessment, though established cut-off points may vary based on factors like ethnicity and body composition.
Elderly and Ill Patients: In cases where accurate height and weight measurements are difficult (e.g., bedridden patients), MUAC provides a reliable alternative for assessing nutritional status.

Frequently Asked Questions

No, it is not recommended. Specialized MUAC tapes are made from a non-stretch, durable material and are often color-coded for easy interpretation. The use of a standard tape measure could lead to inaccurate readings.

To find the midpoint, first bend the person's arm at a 90-degree angle. Measure the distance between the tip of the shoulder (acromion) and the tip of the elbow (olecranon). The midpoint is then marked halfway along this distance.

The colors on a child's MUAC tape correspond to their nutritional status: green for normal, yellow for moderate acute malnutrition, and red for severe acute malnutrition.

MUAC is often preferred over BMI for rapid field screening, particularly for acute malnutrition (wasting), because it is highly portable, inexpensive, and requires less training. However, both have different strengths, and MUAC has been shown to have lower sensitivity in some populations compared to weight-for-height z-scores.

In individuals with nutritional edema, a condition where fluid retention causes swelling, a MUAC reading might appear falsely high, masking the true extent of malnutrition. This is why a physical examination for edema is an important part of a complete nutritional assessment.

Yes, there are different tapes designed for different populations. Tapes for children (6-59 months) typically use a specific color-coding, while tapes for adults and pregnant women have different scales and often lack color codes.

MUAC is particularly useful in public health, humanitarian, and emergency settings where rapid, reliable, and large-scale nutritional screening is necessary. It is also beneficial for home-based monitoring and in clinics with limited resources.

A low MUAC reading, especially in the red zone for severe acute malnutrition, often triggers an immediate referral for life-saving treatment. This may include feeding programs that use ready-to-use therapeutic food (RUTF) and providing comprehensive care.