The 'MUST' calculator can be used to establish nutritional risk using either objective measurements to obtain a score and a risk category or subjective criteria to estimate a risk category but not a score.

Please select which method of nutritional screening is to be used:

Complete all relevant fields and click/tap the 'show results' button.


**Acute Disease Effect (ADE) - select yes if acutely ill and if there has been or is likely to be no nutritional intake for more than 5 days. Note that ADE is unlikely to occur outside hospital.



BMI Score:


Unplanned Weight Loss*:


Weight Loss Score:


Acute Disease Score:


Total Score:


*If any weight loss was planned, unplanned weight loss will be 0% and weight loss score 0.

Risk Category:  

Action Plan:

It is recommended that objective measurements of height, weight, and weight loss are used whenever possible. If you have been unable to measure height you can use the calculator at the bottom of this page to estimate height from the ulna length. However, if actual measurements are not available or reliable and realistic self-reported values cannot be obtained, subjective criteria can be used to inform judgment and establish a malnutrition category.

If height, weight or BMI cannot be obtained, the following criteria which relate to them can assist your judgment of the subject’s nutritional risk category. Please note, these criteria should be used collectively not separately as alternatives to steps 1 and 2 of ‘MUST’ and are not designed to assign a score.

Mid upper arm circumference (MUAC) may be used to estimate BMI category in order to support your overall impression of the subject’s nutritional risk.


MUAC Figure 1 The subject's left arm should be bent at the elbow at a 90 degree angle, with the upper arm held parallel to the side of the body. Measure the distance between the bony protrusion on the shoulder (acromion) and the point of the elbow (olecranon process). Mark the mid-point.

MUAC Figure 2 Ask the subject to let arm hang loose and measure around the upper arm at the mid-point, making sure that the tape measure is snug but not tight.

If MUAC is <23.5 cm, BMI is likely to be <20 kg/m2.

If MUAC is >32.0 cm, BMI is likely to be >30 kg/m2.

The use of MUAC provides a general indication of BMI and is not designed to generate an actual score for use with 'MUST'.

For further information on use of MUAC please refer to The 'MUST' Explanatory Booklet.

  1. BMI
    Clinical impression – thin, acceptable weight, overweight. Obvious wasting (very thin) and obesity (very overweight) can also be noted.
  2. Unplanned weight loss
    Clothes and/or jewellery have become loose fitting (weight loss).
    History of decreased food intake, reduced appetite or swallowing problems over 3-6 months and underlying disease or psycho-social/physical disabilities likely to cause weight loss.
  3. Acute disease effect
    Acutely ill AND no nutritional intake or likelihood of no intake for more than 5 days.
    If the subject is currently affected by an acute patho-physiological or psychological condition, and there has been no nutritional intake or likelihood of no intake for more than 5 days, they are likely to be at nutritional risk. Such patients include those who are critically ill, those who have swallowing difficulties (e.g. after stroke), or head injuries or are undergoing gastrointestinal surgery.
  4. Determine overall risk of malnutrition
    On the basis of estimated BMI category, unplanned weight loss, and Acute Disease Effect, select the appropriate risk category.

BAPEN disclaims any liability to any healthcare provider, patient or other person affected by this resource.

If height cannot be measured, use recently documented or self-reported height (if reliable and realistic).

If the subject does not know or is unable to report their height, it can be estimated from length of ulna by entering the following:

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