BMI (Body Mass Index) is a numerical value derived from your height and weight. It's calculated using the formula: BMI = weight (kg) / height (m)² or BMI = (weight in pounds × 703) / (height in inches)². BMI is used as a screening tool to identify potential weight problems in adults.

What is a healthy BMI range?

A healthy BMI range is typically between 18.5 and 24.9. This range is associated with the lowest risk of weight-related health problems. BMI categories are: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), and Obese (≥30).

BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat mass, and may not be accurate for athletes with high muscle mass, elderly individuals, pregnant women, or certain ethnic groups. It's best used as a starting point for health assessment.

Does BMI change with age and gender?

BMI ranges are generally the same for adults regardless of age or gender. However, body composition changes with age, and BMI may be less accurate for older adults. For children and teens, BMI is interpreted differently using age and gender-specific percentile charts.

Is BMI accurate for athletes?

BMI may not be accurate for athletes or very muscular individuals because muscle weighs more than fat. A muscular person might have a high BMI but low body fat percentage. Additional measurements like body fat percentage or waist-to-hip ratio may be more appropriate for athletes.

Can I use BMI during pregnancy?

BMI calculations during pregnancy are not recommended because weight gain is expected and necessary. Instead, healthcare providers use pre-pregnancy BMI to determine appropriate weight gain recommendations during pregnancy.

How is BMI calculated for children?

For children and teens (ages 2-20), BMI is calculated the same way but interpreted differently. It's compared to other children of the same age and gender using percentile charts. A BMI between the 5th and 85th percentiles is considered healthy.

What health risks are associated with high BMI?

High BMI (overweight and obese categories) is associated with increased risk of heart disease, type 2 diabetes, high blood pressure, stroke, certain cancers, sleep apnea, and joint problems. However, BMI is just one factor in assessing health risks.

What health risks are associated with low BMI?

Low BMI (underweight category) can be associated with malnutrition, osteoporosis, weakened immune system, anemia, and fertility issues. Being underweight can also indicate underlying health conditions that should be evaluated by a healthcare provider.

How can I improve my BMI?

To improve BMI: 1) Focus on sustainable lifestyle changes rather than quick fixes, 2) Eat a balanced diet with appropriate portions, 3) Engage in regular physical activity, 4) Get adequate sleep, 5) Manage stress, and 6) Consult with healthcare professionals for personalized guidance.

What's the difference between BMI and body fat percentage?

BMI is a simple height-to-weight ratio, while body fat percentage measures the actual proportion of fat in your body. Body fat percentage provides more detailed information about body composition and can be more accurate for athletes or people with unusual muscle mass.

Are there different BMI standards for different populations?

Yes, some organizations recommend different BMI cutoffs for Asian populations due to higher health risks at lower BMI levels. The WHO recommends lower overweight thresholds (23-27.4) for Asian populations, while the standard WHO ranges (18.5-24.9 normal) are used for most other populations.

How often should I calculate my BMI?

BMI should be calculated periodically to track changes, but not obsessively. Monthly measurements are reasonable for most people. Remember that BMI can fluctuate due to water retention, muscle gain, or other factors, so focus on trends rather than daily changes.

How does BMI relate to mental health?

BMI can impact mental health through body image concerns, but it's important to remember that BMI is just a number. Focus on overall health, energy levels, and how you feel rather than just the BMI value. Seek professional help if you're experiencing body image or eating concerns.

What are the main limitations of BMI?

BMI limitations include: doesn't distinguish between muscle and fat, doesn't account for bone density, doesn't consider body fat distribution, may not be accurate for very tall or short people, doesn't account for age-related body composition changes, and doesn't consider individual health factors.

What are the BMI ranges and categories?

BMI ranges and categories: Underweight (BMI below 18.5), Normal weight (BMI 18.5-24.9), Overweight (BMI 25-29.9), Class 1 Obesity (BMI 30-34.9), Class 2 Obesity (BMI 35-39.9), Class 3 Obesity (BMI 40+). These BMI classes help assess health risks.

How do I calculate BMI for UK and NHS standards?

The UK BMI calculator and NHS BMI calculator use the standard formula: BMI = weight (kg) / height (m)². The NHS uses BMI ranges to assess healthy weight in the UK population. BMI categories are consistent with WHO standards.

How to calculate BMI in Australia?

The BMI calculator for Australia uses the standard international formula. Australian BMI standards follow WHO guidelines. Calculate BMI using metric (kg, cm) or imperial (lbs, ft/in) units.

What is the BMI calculator for Indian population?

BMI calculator for Indians uses adjusted thresholds: overweight BMI 23-27.4, obesity BMI ≥27.5. This Indian BMI standard reflects higher health risks at lower BMI levels in Asian populations.

What is waist to hip ratio?

Waist to hip ratio (WHR) is calculated by dividing waist by hip circumference. For men, WHR above 0.90 indicates obesity; for women, above 0.85. WHR indicates fat distribution better than BMI alone.

How does pregnancy BMI calculator work?

Pregnancy BMI calculator uses pre-pregnancy BMI to determine healthy weight gain. Recommended gain: Underweight 28-40 lbs, Normal 25-35 lbs, Overweight 15-25 lbs, Obese 11-20 lbs.

Daily Energy Planning

Basal Metabolic Rate (BMR) Calculator

Calculate how many calories your body burns at rest and convert that into daily energy targets. Adjust for activity level and goals to plan sustainable weight loss, maintenance, or muscle gain.

Mifflin-St Jeor equationActivity multipliersGoal-based calorie targets

Choose your preferred measurement units

BMR & Calorie Calculator

Calculate your daily calorie needs

Gender *

Age *

Weight (kg) *

Height (cm) *

Activity Level *

Goal *

Calorie and macro estimates support informed planning but do not replace medical nutrition therapy. Consult a professional for personalized advice.

Clinically Trusted Formulas

The calculator uses the Mifflin-St Jeor equation, validated by dietitians for both men and women. Enter age, height, weight, gender, and activity level to get precise BMR and TDEE estimates instantly.

Personalized Calorie Targets

Select weight loss, maintenance, or gain goals to see recommended daily calories and expected weekly progress. The tool applies scientifically supported calorie surpluses or deficits for realistic results.

Macro Guidance Included

Translate calorie targets into daily protein, carb, and fat grams. Use the suggested macro split as a baseline and adjust to fit individual preferences or dietitian recommendations.

How to Use the BMR Calculator

Basal metabolic rate is the number of calories your body needs at complete rest. Combine it with your activity level to plan sustainable nutrition strategies.

•Choose metric or imperial units so your inputs match familiar measurements.
•Enter accurate age, weight, and height values—re-measure if it has been more than 4 weeks.
•Select your daily activity level. Include both structured workouts and occupational movement.
•Pick a goal: maintenance, gradual fat loss, or strategic muscle gain.

Understanding Your Results

Your dashboard includes BMR, total daily energy expenditure (TDEE), calorie targets, and weekly change estimates. Use the output to design meal plans, recovery strategies, or training phases.

•BMR reflects resting calorie needs before accounting for activity.
•TDEE multiplies BMR by the activity factor to estimate total energy needs.
•Goal calories apply a 500 calorie deficit or surplus for safe weekly changes.
•Macro suggestions break calories into 30% protein, 40% carbs, and 30% fats for balanced nutrition.

Frequently Asked Questions

Is the Mifflin-St Jeor equation better than Harris-Benedict?

How often should I recalculate my BMR?

Can I rely on BMR calculations for weight loss?

How do I adjust macros for special diets?