VoltraBMI: calculator, and what your number means
BMI is your weight in kilograms divided by your height in metres, squared [1]. For adults, the WHO defines overweight as a BMI of 25 or more and obesity as 30 or more [1], and England's NICE puts a healthy weight at 18.5 to 24.9 [2].
For people of Middle Eastern, South Asian, Chinese, other Asian, Black African or African–Caribbean background, NICE uses lower cut-offs: overweight from 23 and obesity from 27.5, because their health risks start at a lower BMI [2].
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What the numbers mean
| Category | Most adults | Middle Eastern, Asian and other backgrounds |
|---|---|---|
| Healthy weight | 18.5–24.9 | 18.5–22.9 |
| Overweight | 25–29.9 | 23–27.4 |
| Obesity | 30 or more | 27.5 or more |
NICE recommendations 1.9.10 and 1.9.11 [2]. For the second group, NICE says obesity classes 2 and 3 are usually identified by reducing the usual thresholds (35 and 40) by 2.5 [2]. The WHO's own definitions are 25 and 30 [1].
Why the lower cut-offs
NICE says people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African–Caribbean background are prone to central adiposity, fat around the middle, and their cardiometabolic risk occurs at a lower BMI [2]. That includes most people in the Gulf.
When BMI misleads
- If you have a lot of muscle, BMI may be a less accurate measure, and NICE says to interpret it with caution [2]. A strength-trained lifter can read "overweight" with little fat. The waist-to-height ranges below apply to people with a lot of muscle too [2].
- Over 65, NICE also advises caution, noting the possible protective effect of a slightly higher BMI when older [2].
- A healthy BMI can still come with fat around the middle, which is why NICE asks for clinical judgement in that range [2]. The WHO calls BMI a surrogate marker of fatness, and says measurements such as waist circumference help [1].
Check your waist too
For adults with a BMI under 35, NICE recommends measuring waist-to-height ratio as well [2]: 0.4 to 0.49 is healthy, with no increased health risk; 0.5 to 0.59 means increased risk; 0.6 or more, further increased risk [2]. These ranges are for both sexes and all ethnicities [2]. NICE's advice is to keep your waist to less than half your height [2].
To measure it, find the bottom of your ribs and the top of your hips, wrap the tape midway between them, just above the belly button, and breathe out naturally before you read it [2]. Then divide your waist by your height, both in cm.
Saudi Arabia's health ministry uses a waist tape on which the risk stage starts at 80 cm for women and 94 cm for men [3]. Our belly fat guide covers what shrinks it.
In Voltra
Voltra shows your BMI on your profile in the You tab, coloured by the WHO ranges, and when it projects your goal weight it never goes below a BMI of 18.5.
Frequently asked
What is a healthy BMI?
18.5 to 24.9 for most adults. For people of Middle Eastern, South Asian and some other backgrounds, NICE puts overweight from 23, so the healthy range ends at 22.9.
How do I calculate my BMI?
Divide your weight in kg by your height in metres squared. At 80 kg and 1.75 m: 80 ÷ (1.75 × 1.75) = 26.1.
Is BMI accurate if I lift weights?
Less so. NICE says to interpret BMI with caution in adults with high muscle mass; check your waist-to-height ratio as well.
What BMI counts as obese?
30 or more on the WHO definition; 27.5 or more for Middle Eastern, South Asian and some other backgrounds, according to NICE.
Sources
- World Health Organization (2025). Obesity and overweight (fact sheet). Page dated 8 December 2025.
- NICE (2022). Overweight and obesity management (NG246): identifying and assessing overweight, obesity and central adiposity, recommendations 1.9.7–1.9.15. Recommendations 1.9.7–1.9.15.
- وزارة الصحة، المملكة العربية السعودية (٢٠١٩). متر الصحة. In Arabic. The waist-tape graphic.
Sources checked on 30 September 2026.
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