Calculate your neck-to-height ratio and height-based neck circumference cutoffs, including sex-specific STOP-BANG sleep apnea screening levels.
Neck Circumference-to-Height Ratio Formula
NHR = Neck Circumference / Height
- NHR = neck-to-height ratio (unitless)
- Neck Circumference = measured around the neck just below the larynx (Adam’s apple)
- Height = standing height in the same length unit as neck circumference
Both measurements must use the same unit so the ratio cancels out. The Neck Index is the same value expressed as a percentage: NHR × 100. Height-based zone cutoffs come from rearranging the formula: borderline neck = 0.20 × height, elevated neck = 0.25 × height.
This is a screening calculation, not a diagnostic test. It does not replace a sleep study or clinical evaluation.
Reference Values and Zones
The ratio bands below are the screening thresholds the calculator uses. The neck-size cutoffs in the second table come from the STOP-BANG sleep apnea screening tool.
| NHR | Zone | Screening signal |
|---|---|---|
| Below 0.20 | Low | No elevated signal from this metric |
| 0.20 to 0.249 | Borderline | Symptoms matter more than the ratio |
| 0.25 and above | Elevated | Higher OSA risk; consider clinical screening |
| Sex | Neck cutoff | Source |
|---|---|---|
| Male | 17 in (43.2 cm) | STOP-BANG |
| Female | 16 in (40.6 cm) | STOP-BANG |
Worked Example
A person is 175 cm tall with a neck circumference of 42 cm.
- NHR = 42 / 175 = 0.240
- Neck Index = 24.0%
- Zone: borderline (between 0.20 and 0.25)
- Elevated cutoff at this height: 0.25 × 175 = 43.75 cm
How to Measure Your Neck
Stand with your head facing forward. Wrap a flexible tape around your neck just below the Adam’s apple, keeping the tape level and snug without compressing the skin. Take the reading at the end of a normal exhale. Measure twice and average if the readings differ.
FAQ
Is a high NHR the same as having sleep apnea? No. NHR is one screening signal. Diagnosis requires a sleep study.
Why use neck size instead of BMI? Neck circumference reflects upper-airway soft tissue more directly than overall weight, which is why it appears in OSA screening tools.
Does the cutoff change with age? The 0.20 and 0.25 thresholds are applied the same way for adults. Children use different reference data.
What if my ratio is elevated but I have no symptoms? Mention it to a clinician. Loud snoring, gasping at night, and daytime sleepiness are the symptoms that matter most.
