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BMI & Calorie Calculator (TDEE)

Body mass index plus your estimated daily calorie needs, based on activity level.

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How to use this calculator

Choose your unit system, enter sex, age, height and weight, and pick your typical activity level. BMI is shown with its category, along with your estimated basal metabolic rate (BMR) and maintenance calories (TDEE). This is a general estimate, not medical advice — see a healthcare provider for personalized guidance.

BMI
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Where your BMI falls —
18.5253040
UnderNormalOverObese

Scale from 15 to 40. The cut-offs (18.5, 25 and 30) are the World Health Organization categories for adults. BMI does not distinguish muscle from fat, so it can misclassify very muscular people, and it is not meant for children, pregnant women or the elderly.

How BMI is calculated

Body Mass Index divides weight by the square of height, giving a simple screening number used widely because it only needs two measurements.

BMI = weight (kg) ÷ height (m)²

BMI categories: under 18.5 is underweight, 18.5–24.9 is normal weight, 25–29.9 is overweight, and 30 or above is classified as obese. BMI doesn't distinguish muscle from fat, so it can be misleading for very muscular individuals.

How BMR and TDEE are calculated

Basal Metabolic Rate (BMR) is the calories your body burns at complete rest, just to keep basic functions running. This tool uses the Mifflin-St Jeor equation, widely considered one of the more accurate formulas for the general population:

Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to estimate total calories burned per day, including movement and exercise — this is your maintenance calorie level.

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Using TDEE for a goal

To maintain weight, eat around your TDEE. A common approach for weight loss is a modest deficit (roughly 300-500 calories below TDEE), and for weight gain, a similar surplus — always alongside professional guidance for anything beyond general awareness.

Frequently asked questions

Is BMI accurate for everyone?

BMI is a population-level screening tool, not a diagnosis. It doesn't account for muscle mass, bone density, or body composition, so it can misclassify very muscular or very lean individuals. Use it as one data point, not the whole picture.

Is this medical advice?

No — this tool provides general estimates for informational purposes only. For personalized nutrition or health guidance, consult a doctor, dietitian, or other qualified professional.

How is BMI calculated?

BMI = weight (kg) divided by height (m) squared. A 70 kg person 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) = 22.9.

What is a healthy BMI range?

For adults, 18.5–24.9 is considered normal, 25–29.9 overweight and 30+ obese. It is a rough screen, not a diagnosis.

How many calories do I need a day?

It depends on your BMR and activity. A rough average is 2,000 kcal for women and 2,500 for men, which the tool refines from your details.