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About this tool
Compare your neck measurement against published screening cut-offs for overweight, obesity and sleep apnoea risk, with an optional BMI cross-check.
The Neck Circumference Risk Checker compares a single tape measurement against the published screening cut-offs that use neck size as a proxy for upper-body fat: Ben-Noun's 37 cm (men) and 34 cm (women) thresholds for a BMI of 25 or more, and the neck criteria used inside sleep apnoea questionnaires. An optional height and weight entry runs a BMI cross-check so you can see when the two measures disagree. It is a screening prompt for a conversation with a clinician, never a diagnosis.
Open Neck Circumference Risk Checker on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Every threshold comes from published screening research rather than a made-up scale.
Shows the adiposity cut-offs and the sleep apnoea cut-offs independently instead of merging them into one score.
Flags the common cases where neck size and BMI point in opposite directions and explains why.
The STOP-BANG questionnaire scores a point for a neck circumference greater than 40 cm (about 16 inches) in either sex, and sleep clinics commonly treat 43 cm (17 in) in men and 41 cm (16 in) in women as a stronger signal. Neck size is only one of several risk factors, so a large neck on its own is not a diagnosis and a normal neck does not rule apnoea out.
Stand upright and wrap the tape horizontally at the level of the cricothyroid membrane — the soft dip just below the Adam's apple — keeping it perpendicular to the neck rather than sloping. Pull it snug without compressing the skin and read it at the end of a normal breath out, to the nearest 0.5 cm.
In Ben-Noun's 2001 screening study, a neck of 39.5 cm or more in men and 36.5 cm or more in women flagged a BMI of 30 or above, while 37 cm and 34 cm respectively flagged a BMI of 25 or above. Those were population screening thresholds, so an individual result can fall either side of the line without matching their actual BMI.
Yes — neck circumference cannot distinguish muscle from fat, so rugby players, wrestlers and heavy lifters routinely exceed these cut-offs with low body fat. That is exactly why the tool offers a BMI cross-check and why any flag should be interpreted alongside waist measurement, blood pressure and symptoms rather than acted on alone.
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