How do you measure the MUAC?

December 20, 2025 •

3 min read

According to UNICEF, using a Mid-Upper Arm Circumference (MUAC) tape is a simple yet effective tool for quickly detecting malnutrition, especially in children. This critical measurement provides a rapid assessment of an individual's nutritional status, particularly valuable in situations where weighing is impractical. The following guide details exactly how you measure the MUAC to ensure accurate results.

Quick Summary

A step-by-step guide explains the correct procedure for measuring Mid-Upper Arm Circumference (MUAC) using a specialized tape. It details how to locate the midpoint of the arm, wrap the tape with appropriate tension, read the result, and interpret the color-coded outcome.

Key Points

Standardized Procedure: Follow a consistent, step-by-step technique to accurately measure MUAC, ensuring reliability and comparability of results.
Use the Correct Arm: Always measure the left arm unless there is a specific contraindication, as using the non-dominant arm ensures consistent muscle relaxation.
Find the Midpoint: Precisely locate the halfway point between the shoulder and elbow tips using a tape measure to ensure the measurement is taken at the correct position.
Apply Correct Tension: The MUAC tape must be snug against the skin but not indent it, as incorrect tension can significantly alter the reading.
Read the Color Code: Interpret the color-coded tape to quickly determine the nutritional status, with red indicating severe, yellow moderate, and green adequate nutrition.
Prioritize Training: Effective MUAC measurement, even with a simple tool, requires minimal training to avoid common errors and ensure accuracy in the field.
Record Accurately: Document the measurement to the nearest millimeter or 0.1 centimeter to maintain a precise record of nutritional status over time.

Understanding the MUAC Measurement

Mid-Upper Arm Circumference, or MUAC, is a simple and reliable anthropometric measurement used to assess nutritional status. It is particularly effective for screening for acute malnutrition in children aged 6 to 59 months, as well as in pregnant and postpartum women and adults. The measurement focuses on the circumference of the upper arm at its midpoint, providing a proxy for muscle and fat reserves, which are depleted in cases of malnutrition.

Unlike traditional methods that require bulky scales, MUAC measurement uses a special, color-coded tape, making it highly portable and easy to use in various settings, from remote communities to health clinics. The technique is non-invasive and requires minimal training, allowing it to be performed by community health workers and even caregivers. By mastering how to measure the MUAC correctly, you can play a crucial role in early detection and intervention for those at nutritional risk.

Equipment Needed

To perform an accurate MUAC measurement, you will need:

A MUAC tape: This is a non-stretchable, flexible tape, often made of plasticized paper, and is color-coded with specific cut-off points. It is graduated in millimeters and is specifically designed for this purpose.
An erasable pen or marker: For marking the midpoint of the arm to ensure accuracy and consistency.

Step-by-Step Guide to Measuring MUAC

Follow these steps to accurately measure the MUAC, using the left arm for consistency unless there's an injury.

Prepare the individual: Ask the person being measured to remove any clothing covering their left upper arm. Explain the procedure clearly to gain their cooperation. The arm should hang relaxed at their side.
Locate the midpoint: Ask the person to bend their left arm at a 90-degree angle, with the forearm parallel to the floor. Locate the bony tip of the shoulder (acromion) and the bony tip of the elbow (olecranon). Place the zero end of the tape measure at the shoulder tip and extend it to the elbow tip. Find the midpoint between these two points and mark it with a pen.
Position the tape: Instruct the person to relax their arm, allowing it to hang loosely at their side. Wrap the MUAC tape around the arm at the marked midpoint.
Ensure correct tension: Pull the tape so it is snug against the arm but not so tight that it compresses the skin. The tape must be flat around the skin, with the numbers facing upright for easy reading. There should be no slack in the tape.
Read the measurement: Read the measurement at the window where the arrows meet. Note the numerical value and, if using a color-coded tape, the color displayed. For example, a result could be 12.0 cm in the yellow zone.
Record the result: Immediately record the measurement to the nearest 0.1 cm (or millimeter) and note the corresponding color. If multiple readings are taken, record the average.

Interpreting MUAC Results

While exact cut-offs can vary by protocol and population, color-coded MUAC tapes provide a simple visual interpretation, especially useful for children aged 6 to 59 months.


MUAC Measurement Interpretation for Children (6-59 months)	Color Zone	MUAC Measurement	Nutritional Status	Action
Green	≥ 12.5 cm	Adequate	Continue regular monitoring and healthy practices.
Yellow	11.5 cm to < 12.5 cm	Moderate Acute Malnutrition (MAM)	Refer to supplementary feeding program and increase monitoring.
Red	< 11.5 cm	Severe Acute Malnutrition (SAM)	Refer to therapeutic feeding program or nearest health center for immediate treatment.

Importance of Accurate Measurement

Getting an accurate MUAC reading is crucial for making the right clinical decision. Errors such as measuring at the wrong midpoint, pulling the tape too tight or too loose, or incorrect reading can lead to misclassification. Proper training, eye-level measurement, and relaxed arm posture are all essential to minimize these errors. The simplicity and effectiveness of the MUAC measurement are maximized when technique is consistent and precise.

Conclusion

Knowing how to measure the MUAC correctly is a fundamental skill for assessing nutritional status, particularly in vulnerable populations. The process, while straightforward, demands attention to detail to ensure the accuracy of the results. By following the standardized steps—from finding the correct midpoint to applying the tape with the right tension—healthcare workers and trained caregivers can effectively screen for malnutrition. The use of color-coded MUAC tapes simplifies interpretation, enabling rapid, targeted interventions. This simple measurement tool remains a cornerstone of nutritional assessment, contributing significantly to public health efforts worldwide.

Further reading: For detailed specifications on different types of MUAC tapes, consult the UNICEF Supply Division Technical Bulletin on MUAC tapes.

Frequently Asked Questions

MUAC is used to assess the nutritional status of an individual by measuring the circumference of their mid-upper arm, which provides an indication of muscle and fat reserves.

The left arm is typically used for MUAC measurement because it is the non-dominant arm for most people, ensuring a standard, relaxed state for the muscles. This minimizes variability between measurements.

For a child aged 6-59 months, a MUAC measurement of 12.5 cm or greater is considered normal and indicates adequate nutrition.

The colors on a MUAC tape indicate the nutritional status: green signifies adequate nutrition, yellow represents moderate acute malnutrition, and red denotes severe acute malnutrition.

Ideally, MUAC should be measured on bare skin for accuracy. If not possible, it can be measured over a single, thin layer of clothing, but thick clothing should be removed.

Common errors include measuring at the incorrect midpoint, pulling the tape too tightly or leaving it too loose, and not reading the measurement at eye level.

A MUAC reading in the yellow zone indicates moderate acute malnutrition (MAM) and typically requires referral to a supplementary feeding program and increased monitoring.

Yes, MUAC can be used to assess adults, including pregnant women. While some adult tapes are not color-coded, specific cut-off points are used to indicate risk of malnutrition.