how to calculate bmi of body

What is BMI?

BMI stands for Body Mass Index. It is a simple number calculated from your weight and height to estimate whether your body weight is in a healthy range for your height. Doctors, trainers, and health apps use BMI as a quick screening tool.

It is not a direct measure of body fat, but it helps identify whether you may be underweight, at a healthy weight, overweight, or obese.

BMI Formula: How to Calculate It

1) Metric Formula (kg and meters)

If your height is in centimeters, convert it first:

• Height in meters = height in cm ÷ 100
• Then square the height: height × height

2) Imperial Formula (lb and inches)

For imperial units, convert feet to inches first:

• Total height (in) = (feet × 12) + inches

Step-by-Step BMI Calculation (Manual Method)

Metric Example

Suppose your weight is 70 kg and your height is 175 cm:

• Convert height: 175 cm = 1.75 m
• Square height: 1.75 × 1.75 = 3.0625
• BMI = 70 ÷ 3.0625 = 22.86

Your BMI is approximately 22.9.

Imperial Example

Suppose your weight is 180 lb and height is 5 ft 10 in:

• Convert height: (5 × 12) + 10 = 70 inches
• Square height: 70 × 70 = 4900
• BMI = 703 × 180 ÷ 4900 = 25.82

Your BMI is approximately 25.8.

BMI Categories (Adults)

BMI Range	Category
Below 18.5	Underweight
18.5 to 24.9	Normal weight
25.0 to 29.9	Overweight
30.0 and above	Obesity

Why People Use BMI

• It is quick and easy to calculate.
• No lab tests are needed.
• It helps track weight trends over time.
• It gives a first-level health risk signal.

Important Limitations of BMI

BMI is useful, but it does not tell the full story of health. It does not measure body fat percentage or fat distribution directly.

• Muscular people may have a high BMI but low body fat.
• Older adults may have normal BMI with lower muscle mass.
• Body fat location (especially around the waist) matters and is not captured.
• Children and teens use age- and sex-specific BMI percentiles, not adult ranges.

Better Ways to Use BMI

Use BMI together with other health markers:

• Waist circumference
• Body fat percentage
• Blood pressure and blood sugar
• Activity level and nutrition habits
• Sleep quality and stress management

Quick Tips If Your BMI Is Out of Range

If BMI is high

• Create a mild calorie deficit with balanced meals.
• Walk daily and include strength training 2–4 times/week.
• Reduce sugary drinks and ultra-processed snacks.

If BMI is low

• Increase calorie intake using nutrient-dense foods.
• Eat enough protein and include resistance exercise.
• Check for underlying medical causes if weight loss is unexplained.

Final Thoughts

If you were wondering how to calculate BMI of body, the process is straightforward: use your weight and height in either metric or imperial formula, then compare your result with standard BMI categories.

Use the calculator above for instant results, and remember that the best health decisions come from looking at BMI along with your lifestyle, medical history, and overall fitness.