BMI Calculator & Calorie Counter

Your complete health assessment tool with personalized nutrition guidance, meal planning tips, and expert insights for sustainable weight management and wellness.

📊 Enter Your Details

Choose the option that best describes your typical weekly activity

🎯 Quick Start Guide

Step 1: Enter Details

Input your age, gender, height, and weight using your preferred units

Step 2: Set Activity Level

Choose how active you are during a typical week

Step 3: Get Results

Receive personalized BMI analysis and calorie recommendations

Understanding Your BMI: Beyond the Numbers

What BMI Actually Measures

Body Mass Index (BMI) is a numerical value calculated from your height and weight using the formula: weight (kg) ÷ height² (m²). Developed in the 1830s by Belgian statistician Adolphe Quetelet, it was originally designed to study population trends, not individual health.

Today, BMI serves as a quick screening tool that healthcare providers use alongside other measurements. It's helpful for identifying potential weight-related health risks across large populations, but it has important limitations when applied to individuals.

The Four BMI Categories Explained

Underweight (BMI < 18.5)

May indicate inadequate nutrition, eating disorders, or underlying health conditions. Associated risks include weakened immune system, nutrient deficiencies, decreased muscle mass, and fertility issues. If you're in this range, consult a healthcare provider to rule out medical causes.

Normal Weight (BMI 18.5-24.9)

Generally associated with lower risk of weight-related health problems. However, "normal" BMI doesn't guarantee good health—body composition, fitness level, diet quality, and lifestyle factors are equally important. Someone with normal BMI but poor diet and no exercise may still face health risks.

Overweight (BMI 25-29.9)

May increase risk of heart disease, type 2 diabetes, and high blood pressure, though risk varies significantly by individual. Some people in this range are quite healthy, especially if they're physically active with good muscle mass. Focus on overall health markers (blood pressure, cholesterol, blood sugar) rather than just the number.

Obese (BMI ≥ 30)

Typically associated with higher risk of serious health conditions including cardiovascular disease, type 2 diabetes, certain cancers, sleep apnea, and joint problems. However, health improvements can begin with even modest weight loss (5-10% of body weight). Work with healthcare providers to develop a safe, sustainable approach to weight management.

⚠️ Important BMI Limitations

  • • Doesn't measure body composition: BMI can't distinguish between muscle and fat. A muscular athlete may have "overweight" BMI despite low body fat.
  • • Ignores fat distribution: Abdominal fat (measured by waist circumference) carries higher health risks than fat stored elsewhere.
  • • Doesn't account for age or ethnicity: Optimal BMI ranges may differ for older adults and various ethnic groups.
  • • Overlooks overall fitness: A fit person with higher BMI may be healthier than a sedentary person with "normal" BMI.

The Science of Calories and Metabolism

How Your Body Burns Calories

Your total daily energy expenditure (TDEE) comes from four main components:

1. Basal Metabolic Rate (BMR) — 60-75%

Energy needed for essential functions: breathing, circulation, cell production, nutrient processing. This is what you'd burn in a coma. BMR is influenced by age, gender, body composition, and genetics.

2. Physical Activity — 15-30%

Calories burned during deliberate exercise and movement. This is the component you have the most direct control over. Even non-exercise movement (fidgeting, standing, walking) adds up significantly.

3. Thermic Effect of Food (TEF) — 8-15%

Energy required to digest, absorb, and process nutrients. Protein has the highest TEF (20-30%), followed by carbs (5-10%) and fats (0-3%). This is why high-protein diets may slightly boost metabolism.

4. Non-Exercise Activity (NEAT) — 15-30%

All movement that isn't deliberate exercise: typing, cooking, cleaning, fidgeting, maintaining posture. NEAT varies dramatically between individuals and can account for 100s of calories difference daily.

Why "Calories In vs. Calories Out" Isn't Always Simple

While weight management fundamentally depends on energy balance, the reality is more nuanced than simple math:

Metabolic Adaptation

When you reduce calories, your body may lower its metabolic rate by 10-25% to conserve energy. This "adaptive thermogenesis" means you burn fewer calories than expected for your new weight, making further weight loss more challenging.

Hormonal Influences

Hormones like leptin, ghrelin, insulin, thyroid hormones, and cortisol significantly affect hunger, satiety, and how your body stores or burns fat. Chronic stress, poor sleep, and extreme dieting can disrupt these hormones.

Individual Variation

Two people of the same age, gender, and size can have BMRs that differ by 600+ calories daily due to genetics, thyroid function, muscle mass, and other factors. This is why generic calorie calculators provide estimates, not precise prescriptions.

The Mifflin-St Jeor Formula (What We Use)

This calculator uses the Mifflin-St Jeor equation, developed in 1990 and currently the most accurate formula for the general population:

For Men:

BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5

For Women:

BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Your BMR is then multiplied by an activity factor (1.2 to 1.9) to estimate total daily calories. This formula has an accuracy of approximately ±10%, meaning your actual needs could be 10% higher or lower.

Tip: Start with the calculated calories and monitor your weight for 2-3 weeks. If you're not seeing expected changes, adjust by 100-200 calories and reassess. Your real-world results are more accurate than any formula.

Practical Meal Planning and Nutrition Strategies

Building Balanced, Satisfying Meals

Rather than obsessing over calorie counting, focus on creating meals with these components:

🥩 Protein (¼ of your plate)

20-40g per meal. Helps build muscle, keeps you full, and has the highest thermic effect.

  • • Chicken, turkey, fish, lean beef
  • • Eggs, Greek yogurt, cottage cheese
  • • Tofu, tempeh, legumes, edamame
  • • Protein powder (whey, pea, rice)

🥬 Vegetables (½ of your plate)

High volume, low calorie, packed with nutrients and fiber. Eat a rainbow of colors.

  • • Leafy greens: spinach, kale, arugula
  • • Cruciferous: broccoli, cauliflower, Brussels sprouts
  • • Colorful: peppers, tomatoes, carrots, beets
  • • Other: mushrooms, zucchini, cucumber

🌾 Carbs (¼ of your plate)

Provides energy, especially for active individuals. Choose complex carbs with fiber.

  • • Whole grains: brown rice, quinoa, oats
  • • Starchy vegetables: sweet potato, squash
  • • Legumes: lentils, chickpeas, beans
  • • Whole grain bread, pasta (moderate portions)

🥑 Healthy Fats (1-2 servings)

Essential for hormone production, nutrient absorption, and satiety. Use in moderation as they're calorie-dense.

  • • Olive oil, avocado oil (cooking/dressing)
  • • Nuts and seeds (1 oz serving)
  • • Avocado (¼ to ½ fruit)
  • • Fatty fish: salmon, mackerel, sardines
  • • Nut butters (1-2 Tbsp)
  • • Olives, coconut (moderate amounts)

Sample Daily Meal Plans by Calorie Target

1,500 Calorie Day (Weight Loss for Women)

Breakfast (350 cal): Greek yogurt parfait with berries, granola, and chia seeds
Lunch (450 cal): Grilled chicken salad with mixed greens, quinoa, veggies, and balsamic vinaigrette
Snack (150 cal): Apple with 1 Tbsp almond butter
Dinner (500 cal): Baked salmon (4 oz), roasted sweet potato, steamed broccoli with olive oil
Evening snack (50 cal): Herbal tea with small handful of berries

2,000 Calorie Day (Maintenance for Moderately Active Adult)

Breakfast (450 cal): Scrambled eggs (2 whole + 1 white), whole grain toast, avocado, side of berries
Mid-morning snack (200 cal): Protein smoothie with banana, spinach, protein powder
Lunch (600 cal): Turkey and hummus wrap with whole grain tortilla, mixed vegetables, side salad
Afternoon snack (200 cal): Mixed nuts (1 oz) and string cheese
Dinner (550 cal): Lean beef stir-fry with brown rice, lots of vegetables, light sauce

2,500 Calorie Day (Muscle Gain or Very Active Individual)

Breakfast (550 cal): Oatmeal with protein powder, banana, walnuts, and cinnamon
Mid-morning (300 cal): Protein bar and piece of fruit
Lunch (700 cal): Chicken breast (6 oz), quinoa, roasted vegetables, tahini dressing
Pre-workout (200 cal): Rice cakes with peanut butter
Post-workout (300 cal): Protein shake with banana
Dinner (600 cal): Grilled fish, sweet potato, large green salad with olive oil
Evening (150 cal): Greek yogurt with berries

Note: These are examples only. Individual needs vary based on metabolism, activity intensity, body composition goals, and personal preferences. Adjust portions and food choices to match your specific requirements and dietary restrictions.

Smart Substitutions to Reduce Calories Without Feeling Deprived

Instead of this... ❌

  • • Regular soda (150 cal)
  • • Creamy salad dressing (140 cal)
  • • Fried chicken (350 cal)
  • • Chips as snack (300 cal)
  • • White rice (200 cal)
  • • Full-fat mayo (100 cal)
  • • Sweetened yogurt (150 cal)
  • • Fruit juice (120 cal)

Try this... ✅

  • • Sparkling water with lemon (0 cal) — saves 150 cal
  • • Balsamic vinaigrette (45 cal) — saves 95 cal
  • • Grilled chicken (165 cal) — saves 185 cal
  • • Veggie sticks + hummus (100 cal) — saves 200 cal
  • • Cauliflower rice (25 cal) — saves 175 cal
  • • Mustard or Greek yogurt (20 cal) — saves 80 cal
  • • Plain Greek yogurt + berries (100 cal) — saves 50 cal
  • • Whole fruit (60 cal) — saves 60 cal + adds fiber

💡 Pro Tip: Small Changes Add Up

Making just 3-4 of these swaps daily can save 500+ calories without feeling restrictive. Over a week, that's 3,500 calories saved (roughly equivalent to 0.5 kg / 1 lb of fat loss), achieved simply through smarter choices.

Exercise, Activity, and Calorie Burn

Approximate Calories Burned by Activity (per 30 minutes)

Based on a 70 kg (154 lbs) person. Heavier individuals burn more calories; lighter individuals burn fewer.

Light Activity

  • Walking (3 mph) — 90 cal
  • Light housework — 100 cal
  • Stretching / Yoga — 90 cal
  • Leisurely cycling — 120 cal
  • Gardening — 135 cal

Moderate Activity

  • Brisk walking (4 mph) — 150 cal
  • Swimming (moderate) — 200 cal
  • Dancing — 165 cal
  • Weight training — 135 cal
  • Tennis (singles) — 240 cal

Vigorous Activity

  • Running (6 mph) — 300 cal
  • Jump rope — 340 cal
  • HIIT training — 400 cal
  • Swimming (vigorous) — 300 cal
  • Cycling (14-16 mph) — 360 cal

⚠️ Important Reality Check:

Fitness trackers and gym machines often overestimate calorie burn by 20-30%. If using these numbers for diet planning, be conservative. It's better to underestimate calories burned and overestimate calories eaten than vice versa.

Building an Effective Exercise Routine

For Weight Loss:

  • • Cardio: 150-300 minutes/week of moderate intensity, or 75-150 minutes of vigorous intensity
  • • Strength training: 2-3 sessions/week targeting all major muscle groups
  • • Daily movement: Aim for 8,000-10,000 steps, take stairs, park farther away
  • • Why it works: Cardio creates immediate calorie deficit; strength training preserves muscle during weight loss and boosts metabolism long-term

For Muscle Gain:

  • • Strength training: 4-6 sessions/week with progressive overload (gradually increasing weight/reps)
  • • Cardio: 2-3 moderate sessions/week to maintain cardiovascular health without interfering with recovery
  • • Rest: 1-2 full rest days per week; muscles grow during recovery, not during workouts
  • • Nutrition: Slight calorie surplus (200-500 cal above maintenance) with 1.6-2.2g protein per kg body weight

For General Health & Maintenance:

  • • Cardio: 150 minutes/week of moderate activity (walking, cycling, swimming)
  • • Strength: 2 sessions/week targeting major muscle groups
  • • Flexibility: Daily stretching or 1-2 yoga sessions/week
  • • Consistency > intensity: Regular moderate activity beats sporadic intense workouts

The Truth About "Spot Reduction" and Fat Loss

❌ Myth: You can target fat loss in specific areas

Despite what Instagram ads claim, doing endless crunches won't give you abs, and thigh exercises won't create a "thigh gap." Your body loses fat systemically based on genetics and hormones, not based on which muscles you exercise.

✅ Reality: Fat loss happens throughout the body

Where you lose fat first (and last) is determined by genetics, gender, and hormone levels. Men typically store fat in the abdomen and lose it last from there. Women often store fat in hips and thighs and lose it last from those areas.

The solution:

  • • Create a calorie deficit through diet and exercise
  • • Build muscle throughout your body with resistance training
  • • Be patient—targeted areas will eventually slim down
  • • Focus on overall health and strength, not just aesthetics

Common Mistakes That Sabotage Progress

❌ What NOT to Do

Crash Dieting (Under 1200 cal for women, 1500 for men)

Extreme deficits slow metabolism, cause muscle loss, trigger binge eating, and are impossible to sustain. You'll regain weight plus extra when you inevitably return to normal eating.

Eliminating Entire Food Groups

Unless you have a medical condition, cutting out carbs, fats, or other food groups isn't necessary and makes diets harder to maintain. Sustainable plans include all macronutrients in appropriate amounts.

Relying Only on Exercise for Weight Loss

"You can't outrun a bad diet." A single cheeseburger (500 cal) requires running 5 miles to burn off. Exercise is crucial for health but weight loss is 70-80% diet.

Weighing Daily and Panicking Over Fluctuations

Your weight can fluctuate 1-2 kg daily due to water retention, food timing, hormones, sodium intake, and bathroom schedules. Track weekly averages, not daily numbers.

Drinking Your Calories

Liquid calories (soda, juice, specialty coffees, alcohol) don't trigger satiety like solid food. A Starbucks Frappuccino can have 500+ calories but won't make you feel as full as a meal.

✅ What to Do Instead

Aim for Moderate, Sustainable Deficits

Create a 300-500 calorie daily deficit (500-750 for those with significant weight to lose). This allows steady progress while preserving muscle, energy, and sanity.

Eat Balanced, Flexible Meals

Include protein, complex carbs, healthy fats, and vegetables in most meals. Allow room for treats in moderation (80/20 rule: 80% nutrient-dense foods, 20% flexibility for enjoyment).

Combine Diet and Exercise Strategically

Use diet to create most of your calorie deficit (easier to not eat 300 calories than to burn them). Use exercise to preserve muscle, improve health markers, and boost mood.

Track Trends, Not Daily Fluctuations

Weigh yourself same time daily (morning, after bathroom, before eating) and look at the weekly average. Take progress photos and measurements—scale weight doesn't tell the full story.

Prioritize Water and Whole Foods

Drink 2-3 liters of water daily. Save liquid calories for special occasions. Choose foods you can chew—they're more satiating and easier to track accurately.

🏥 When to Seek Professional Medical Advice

While this calculator provides general guidance, certain situations require professional medical evaluation and support:

Consult a Doctor If:

  • • BMI under 18.5 or over 30
  • • Rapid, unexplained weight loss or gain
  • • History of eating disorders
  • • Chronic health conditions (diabetes, heart disease, thyroid issues)
  • • Taking medications that affect weight or metabolism
  • • Pregnancy or breastfeeding
  • • Planning to lose more than 10% of body weight
  • • Age under 18 or over 65

Work with a Registered Dietitian For:

  • • Personalized meal planning
  • • Managing specific dietary needs (allergies, intolerances, preferences)
  • • Athletic performance optimization
  • • Managing health conditions through diet
  • • Overcoming plateaus
  • • Developing sustainable long-term eating habits
  • • Addressing relationship with food
  • • Evidence-based supplement guidance

⚠️ Critical Warning Signs:

If you experience chest pain, severe fatigue, dizziness, fainting, irregular heartbeat, or other concerning symptoms during dieting or exercise, seek immediate medical attention. Extreme or rapid weight loss methods can be dangerous.

📖 Complete User Guide: How to Use This Calculator Effectively

Step-by-Step Instructions

  1. Enter accurate measurements: Use your current weight, not your goal weight. For height, measure without shoes. Be honest with your activity level—most people overestimate this.
  2. Choose the right activity multiplier:
    • • Sedentary: Desk job, minimal intentional exercise
    • • Lightly active: Light exercise 1-3 days/week, or active job
    • • Moderately active: Exercise 3-5 days/week at moderate intensity
    • • Very active: Intense exercise 6-7 days/week
    • • Extremely active: Very intense exercise daily + physical job
  3. Review your results: Check your BMI category and healthy weight range. Note your BMR (calories burned at rest) and maintenance calories (to maintain current weight).
  4. Choose appropriate goals: For safe weight loss, start with the 0.5 kg/week target. For muscle gain, use the 0.5 kg/week surplus. Faster isn't better.
  5. Track and adjust: Follow the suggested calories for 2-3 weeks, monitoring weight trends. If results don't match expectations, adjust by 100-200 calories and reassess.
  6. Use the copy/share features: Save your results to track changes over time or share with healthcare providers for more personalized advice.

Understanding Your Results

BMI Value: Your calculated body mass index. Remember this is a screening tool, not a diagnostic tool.

Healthy Weight Range: The weight range where your BMI would fall between 18.5-24.9. This gives you a target zone rather than a single "ideal" weight.

BMR: Calories your body needs for basic functions at complete rest. This is your metabolic baseline.

Maintenance Calories: BMR multiplied by activity factor. Eat this amount to maintain current weight.

Weight Change Targets: Approximate calorie levels for gradual weight loss or gain. These create deficits/surpluses of 500-1000 cal daily for 0.5-1 kg weekly change.

Tips for Best Results

  • • Recalculate every 5-10 lbs of weight loss, as calorie needs decrease with lower body weight
  • • Be honest about activity levels—overestimating leads to weight gain or slower loss
  • • Use a food scale and tracking app for the first few weeks to learn portion sizes
  • • Don't eat back all your exercise calories—they're often overestimated
  • • Give any calorie target at least 2-3 weeks before adjusting—initial changes may be water weight
  • • Focus on non-scale victories: energy levels, sleep quality, fitness improvements, how clothes fit

❓ Frequently Asked Questions

1. Does BMI measure body fat percentage?

No. BMI only uses height and weight—it doesn't distinguish muscle from fat. A bodybuilder and a sedentary person could have identical BMIs despite vastly different body compositions. For body fat percentage, you need specialized testing like DEXA scans, hydrostatic weighing, or bioelectrical impedance analysis (though accuracy varies).

2. Why do some athletes have "overweight" or "obese" BMI?

Muscle is denser than fat. Athletes with significant muscle mass weigh more than their height would "predict" using BMI standards. For example, many NFL players have BMIs over 30 (classified as obese) despite having low body fat percentages. This is why BMI should be used alongside other health indicators.

3. Are the calorie estimates exact?

No calculator can provide exact calorie needs. The Mifflin-St Jeor formula has ~10% margin of error, meaning your actual needs could be 200-300 calories different from the calculation. Individual factors like genetics, thyroid function, gut microbiome, and metabolic adaptation affect actual calorie burn.

4. Why do different calculators give different calorie recommendations?

Different formulas exist (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle), each with slightly different calculations and assumptions. Activity multipliers also vary between calculators. This is normal—treat all estimates as starting points and adjust based on real-world results.

5. Can I use this for weight loss planning?

Yes, as a starting point. Use the calculated calorie targets, track your food intake and weight for 2-3 weeks, then adjust based on results. Combine with balanced nutrition and regular exercise. For complex health situations or significant weight loss goals, work with healthcare professionals.

6. What if my BMI is "normal" but I don't look or feel healthy?

BMI doesn't tell the whole story. You could have normal BMI with high body fat percentage, poor muscle mass, and metabolic issues (sometimes called "skinny fat"). Focus on body composition through strength training, measure waist circumference, and monitor health markers like blood pressure and cholesterol.

7. How often should I recalculate my calorie needs?

Recalculate after losing or gaining 5-10 lbs (2.5-5 kg), as your calorie needs decrease with weight loss and increase with weight gain. Also recalculate if your activity level changes significantly (new job, new exercise routine, injury recovery).

8. Why am I not losing weight at the calculated deficit?

Common reasons: underestimating food intake (portions are larger than you think), overestimating activity/exercise, water retention (especially for women during hormonal fluctuations), metabolic adaptation, inaccurate food labels, or not giving enough time (need 2-3 weeks to see trends). Solution: track more carefully, be patient, or slightly reduce calories.

9. Is it safe to eat below my BMR?

Generally not recommended without medical supervision. Eating well below BMR can trigger metabolic adaptation, muscle loss, hormonal disruption, and nutrient deficiencies. Women shouldn't go below 1200 cal/day, men not below 1500 cal/day, except under medical guidance.

10. Does this calculator store my health data?

No. All calculations happen locally in your browser. No personal data is collected, stored, or transmitted to any server. Your privacy is completely protected. If you refresh the page, you'll need to re-enter your information.

11. Can I use this during pregnancy or while breastfeeding?

While you can calculate baseline BMI, pregnant and breastfeeding women have significantly different calorie needs and appropriate BMI ranges. Pregnancy requires ~300-500 extra calories daily (2nd/3rd trimester), breastfeeding ~450-500 extra. Always consult your OB/GYN or healthcare provider for personalized guidance during these periods.

12. What's the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is calories burned at complete rest for basic bodily functions. TDEE (Total Daily Energy Expenditure) is BMR multiplied by activity factor—it includes all calories burned throughout the day from movement, exercise, digestion, etc. To maintain weight, eat at TDEE. To lose weight, eat below TDEE. To gain, eat above it.

13. Do men and women have different calorie needs at the same size?

Yes. Men typically have higher muscle mass and lower body fat percentage than women at equivalent heights/weights, so they burn more calories at rest. This is why the formula adds 5 calories for men but subtracts 161 for women. Additionally, hormonal differences affect metabolism and fat storage patterns.

14. How does age affect calorie needs?

Metabolism naturally slows with age, primarily due to muscle mass loss. The formula subtracts 5 calories per year of age. This is why maintaining muscle through strength training becomes increasingly important as you age—it helps preserve metabolic rate and functional independence.

15. Should I eat the same calories every day?

Not necessarily. Some people find success with calorie cycling (higher calories on training days, lower on rest days) or intermittent fasting approaches. What matters most is your weekly average. Consistency in average intake matters more than daily perfection. Some flexibility day-to-day can improve adherence.

Privacy & Medical Disclaimer

Privacy: This calculator runs entirely in your browser. No personal data is collected, stored, or transmitted to any server. Your information never leaves your device.

Medical Disclaimer: This tool provides general health information for educational purposes only. It is not medical advice and should not be used as a substitute for professional medical consultation, diagnosis, or treatment.

Accuracy: BMI and calorie calculations are estimates based on population averages and standard formulas. Individual needs vary significantly based on metabolism, health conditions, body composition, activity intensity, and other factors. Always consult qualified healthcare providers for personalized medical, nutrition, or fitness advice, especially if you have existing health conditions or are planning significant lifestyle changes.