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Body Mass Index (BMI) Calculator, Categories & Health Risks

Work out your Body Mass Index, see which range it falls in, and what that does and does not tell you.

A set of bathroom scales with an apple and a tape measure on them

Enter your height and weight to see your BMI.

Where this falls on the BMI scale

BMI classification and the risk of chronic non-communicable disease associated with each range.
Category BMI range Health risk
Underweight < 18.5 Low
Normal Weight 18.5-24.9 Low
Overweight 25-29.9 Moderate
Obesity Class I 30-34.9 Elevated
Obesity Class II 35-39.9 Significantly high
Obesity Class III >= 40 Extremely high

Tips for a healthy BMI

General guidance, the same for everyone - not advice based on your result.

  • Eat a balanced diet

    Vegetables, whole grains and lean protein at most meals. What you eat regularly matters more than what you eat occasionally.

  • Move most days

    Around 150 minutes of moderate activity a week. Walking counts, and consistency counts for more than intensity.

  • Drink enough water

    Thirst is easily mistaken for hunger. Water has no calories and makes the difference easier to tell.

  • Track the trend, not the day

    Weight moves by a kilogram or more within a single day. Only the line over weeks says anything.

Body Mass Index (BMI) Classification and Risk of Chronic Non-Communicable Diseases

The Body Mass Index (BMI) is a standard method for classifying body weight relative to an individual's height. This classification is often used to assess the risk of developing chronic non-communicable diseases such as cardiovascular, respiratory, and endocrine disorders. Below is a detailed breakdown of BMI categories and their associated health risks:

The classification table is rendered by the page itself now, above this text, so it can mark your own result. See KAN-35.

 

Detailed Explanation of Categories

  1. Underweight (BMI < 18.5):

    • Health Overview: Individuals in this category often have insufficient body fat and lean mass.
    • Associated Risks:
      • Low risk of cardiovascular diseases but an increased risk of respiratory infections due to weakened immunity.
      • Possible deficiencies in essential vitamins and minerals.
    • Recommendations: Nutritional intervention and strength training to build healthy weight.

  2. Normal Weight (BMI 18.5–24.9):

    • Health Overview: Considered the optimal BMI range for maintaining long-term health.
    • Associated Risks:
      • Lowest risk for chronic diseases across all categories.
    • Recommendations: Continue a balanced diet and regular physical activity to maintain this status.

  3. Overweight (BMI ≥ 25.0):

    • Pre-obesity (25.0–29.9):
      • Health Overview: Early warning sign of unhealthy weight gain.
      • Associated Risks: Moderate risk of cardiovascular conditions like hypertension and type 2 diabetes.
    • Obesity Class I (30.0–34.9):
      • Health Overview: A clear indicator of excess body fat leading to metabolic complications.
      • Associated Risks: Elevated risk of cardiovascular diseases and endocrine disorders such as insulin resistance.
    • Obesity Class II (35.0–39.9):
      • Health Overview: A severe level of obesity with increasing systemic impacts.
      • Associated Risks: Higher chances of developing respiratory problems, including sleep apnea, and a significant risk of endocrine disorders like diabetes.
    • Obesity Class III (≥ 40.0):
      • Health Overview: Often referred to as morbid or extreme obesity, requiring urgent medical attention.
      • Associated Risks: Substantial risk of life-threatening conditions such as heart failure, chronic respiratory diseases, and severe hormonal imbalances.

Expanded Context on Risks

  • Cardiovascular Diseases: Higher BMI increases the likelihood of conditions such as hypertension, coronary artery disease, and stroke. Excess fat can lead to plaque buildup in arteries, reducing blood flow and increasing strain on the heart.

  • Respiratory Conditions: In cases of obesity, excessive body fat can compress the diaphragm and lungs, reducing respiratory efficiency. This may lead to conditions such as sleep apnea or chronic obstructive pulmonary disease (COPD).

  • Endocrine Disorders: Increased fat accumulation can disrupt hormone levels, leading to insulin resistance, type 2 diabetes, and other metabolic syndromes.

Lifestyle Recommendations

To mitigate the risks associated with BMI categories:

  • Underweight: Incorporate nutrient-rich foods and engage in weight-strengthening exercises.
  • Normal Weight: Maintain your current healthy habits and focus on balanced nutrition.
  • Overweight/Obesity: Adopt a calorie-controlled diet, increase physical activity, and consider professional medical advice for effective weight management.

Want to reach your ideal weight?

BMI tells you where you are. What you eat and burn is what moves it.

Go to Calorie Tracker