BMI Calculator
Calculate your Body Mass Index. Enter your weight and height to find your BMI and health category instantly.
Your Measurements
kg
cm
1618.525303540+
Your BMI
24.2
Category
Normal Weight
Healthy Weight Range (for your height)
53.5–72.0 kg
BMI Scale
Severely Underweight0–16
Underweight16–18.5
Normal Weight18.5–25
Overweight25–30
Obese (Class I)30–35
Obese (Class II)35–40
Obese (Class III)40+
How to Use This Calculator
Enter your weight in kilograms and your height in centimetres. Your BMI and health category are calculated instantly. The colour-coded scale shows where your BMI falls relative to the standard WHO categories. The calculator also shows your healthy weight range for your specific height.
To convert from other units: multiply pounds by 0.453 for kg; multiply feet by 30.48 for cm; multiply inches by 2.54 for cm.
The Formula
BMI = Weight (kg) ÷ [Height (m)]²
Height in metres = Height (cm) ÷ 100
Example: 70 kg, 170 cm
Height in m = 170 ÷ 100 = 1.70 m
BMI = 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2
Healthy weight range:
Minimum = 18.5 × Height² (in m²)
Maximum = 24.9 × Height² (in m²)
BMI Categories
Below 16.0Severely Underweight
16.0–18.4Underweight
18.5–24.9Normal Weight (Healthy)
25.0–29.9Overweight
30.0–34.9Obese — Class I
35.0–39.9Obese — Class II
40.0 and aboveObese — Class III (Morbidly Obese)
Example
Ngozi: 68 kg, 163 cm
Height in metres1.63 m
BMI68 ÷ 2.657 = 25.6
CategoryOverweight
Healthy Range49.1–66.2 kg
Weight to Lose~1.8 kg
Ngozi is just slightly over the healthy range. Losing about 2 kg would bring her BMI to 24.9, the upper edge of the normal category. This is a modest and achievable goal through dietary adjustment alone.
BMI Limitations and Nigerian Context
BMI is a useful screening tool but has important limitations:
- Muscle mass: BMI does not distinguish between muscle and fat. A muscular person may have a high BMI without excess body fat.
- Ethnic variation: Some research suggests that Sub-Saharan African populations may have different health risk thresholds. Nigerian bodies tend to have different fat distribution patterns compared to European populations on which original BMI tables were based.
- Age and sex: BMI does not adjust for age or sex differences in body composition. Older adults typically have more body fat than younger adults at the same BMI.
- Waist circumference: Many health professionals now recommend checking waist circumference alongside BMI. For Nigerians, waist circumference above 90cm (men) or 80cm (women) increases risk for metabolic syndrome.
BMI is a screening tool, not a diagnostic measure. For a proper health assessment, consult a qualified medical professional. High BMI alone does not constitute a diagnosis.
FAQ
BMI is a reasonable first screening tool but it was originally developed based on European populations. Some studies suggest that people of African descent may experience metabolic health risks at lower BMI thresholds than Europeans, particularly for type 2 diabetes risk. The standard WHO thresholds (18.5–24.9 normal) are still widely used in Nigerian clinical practice but should be interpreted alongside other health markers like blood pressure, blood glucose, and waist circumference.
For a healthy BMI of 18.5–24.9, your healthy weight range depends on your height. For example: 160cm height → 47–64 kg; 170cm → 53–72 kg; 175cm → 57–76 kg; 180cm → 60–81 kg. These are guidelines — individual factors like bone density, muscle mass, and medical conditions all affect what weight is truly healthy for you personally.
Yes, obesity rates are rising rapidly in Nigeria, particularly in urban areas. According to national surveys, overweight and obesity affect approximately 20–35% of adult urban Nigerians, with higher rates among women. Rising processed food consumption, sedentary urban lifestyles, and reduced physical activity are key drivers. The prevalence is higher in Lagos, Abuja, and Port Harcourt than in rural areas.