BMI for BMI for 5ft 10in, 90lbs is 12.9 — Severely underweight
A BMI of 12.9 falls in the Severely underweight range. Equivalent to 178cm and 41kg. The ideal weight range for this height is 58–79kg (128–174lbs).
▶ Open full BMI calculatorWhat a BMI of 12.9 means
BMI is a screening tool, not a diagnostic measure. It doesn't account for muscle mass — a muscular athlete may have a high BMI despite low body fat. For a more complete picture, combine BMI with your body fat percentage. The estimated body fat for this BMI is approximately 6% (Deurenberg formula, assumes male aged 30 — use the body fat calculator for personalised results).
The WHO healthy BMI range (18.5–24.9) applies to adults of all ethnicities, though some health bodies recommend lower thresholds for people of Asian descent. Always discuss your results with a qualified healthcare provider.
Frequently asked questions
Is a BMI of 12.9 healthy?+
A BMI of 12.9 is classified as Severely underweight. The healthy BMI range is 18.5–24.9. To reach the healthy range, approximately 17kg would need to be gained.
What is the ideal weight for 5ft 10in?+
For a height of 5ft 10in, the healthy weight range (BMI 18.5–24.9) is 58–79kg (128–174lbs). This range is associated with the lowest health risk according to WHO standards. Note that "ideal" weight varies by individual — muscle mass, bone density, age, and ethnicity all affect what's healthy for a specific person.
How accurate is BMI?+
BMI is a useful population-level screening tool but has individual limitations. It doesn't distinguish between fat and muscle mass — a muscular person may have a high BMI despite having low body fat. It also doesn't account for fat distribution (abdominal fat is more associated with health risk than overall BMI). Use BMI alongside waist circumference and body fat percentage for a more complete picture.