MUST Calculator — Malnutrition Universal Screening Tool
Work out the Malnutrition Universal Screening Tool (MUST) score from BMI, unplanned weight loss in 3–6 months and acute illness — 0 low, 1 medium, 2+ high risk — with the BAPEN action.
How it works
MUST = BMI score (> 20 → 0; 18.5–20 → 1; < 18.5 → 2) + weight-loss score (unplanned loss in 3–6 months < 5% → 0; 5–10% → 1; > 10% → 2) + acute disease effect (acutely ill with no intake for > 5 days → 2). Risk: 0 low · 1 medium · ≥ 2 high.
The Malnutrition Universal Screening Tool was developed by the Malnutrition Advisory Group of BAPEN (2003) and is used in hospitals, care homes and the community across the UK and Europe, and recommended by NICE. It has five steps: BMI score, weight-loss score, acute disease effect, overall risk and a management plan. Low risk means routine care and re-screening (weekly in hospital, monthly in care homes, yearly in the community); medium risk means observing and recording intake; high risk means treatment with a dietitian, unless that would not help, for example at the end of life.
Worked example
A 165 cm adult now weighs 58 kg, down from 63 kg four months ago, and is not acutely ill. BMI = 58 ÷ 1.65² = 21.3 kg/m² (score 0); weight loss = 5 ÷ 63 = 7.9% (score 1); no acute disease effect (0): MUST = 1 — medium risk, so record food intake for 3 days.
Sources: BAPEN — The ‘MUST’ Toolkit · NICE CG32 — Nutrition support for adults
Frequently asked questions
What does a MUST score of 2 mean?
A total of 2 or more is high risk of malnutrition. BAPEN advises treatment: refer to a dietitian or nutrition support team, set goals, improve intake and monitor the care plan.
What if the person cannot be weighed?
BAPEN gives alternatives: estimate height from ulna length and BMI from mid-upper arm circumference, or use subjective signs such as loose clothing. This calculator needs a measured or reliable recalled height and weight.
When is the acute disease effect scored?
Only when the person is acutely ill and has had, or is likely to have, no nutritional intake for more than 5 days — this mainly applies in hospital.
MUST or MNA-SF?
MUST is for adults of any age in any care setting. The MNA-SF was designed specifically for people aged 65 and over and includes mobility and cognition.
Related calculators
Clinical decision tool for education and for use by trained clinicians alongside clinical judgement — not a diagnosis and not a substitute for medical assessment. Scores validated in specific populations may not apply to every patient.