Health & Fitness Calculators
BMI, BMR, calorie needs, body fat, ideal weight, water intake — track your wellness with accurate metrics.
Health and fitness calculators using the WHO/CDC clinical formulas — BMI, BMR, calorie needs, body fat percentage, ideal weight, water intake, macros. Each uses peer-reviewed formulas (Mifflin-St Jeor, Devine, US Navy) rather than approximate rules of thumb.
Health & Fitness
BMI Calculator
Calculate your Body Mass Index (BMI) and find out if your weight is in a healthy range based on WHO guidelines.
Open calculatorCalorie
Calculate your daily calorie needs based on age, weight, height, gender, and activity level. Get targets for weight loss, maintenance, or gain.
Open calculatorBMR Calculator
Calculate your Basal Metabolic Rate — the number of calories your body burns at rest — using the Mifflin-St Jeor equation.
Open calculatorBody Fat
Estimate your body fat percentage using the U.S. Navy method — proven accurate using just a few body measurements.
Open calculatorIdeal Weight Calculator
Calculate your ideal weight using multiple proven formulas — Devine, Robinson, Miller, Hamwi, and BMI-based.
Open calculatorWater Intake
Find out how much water you should drink daily based on your weight, activity level, and climate — research-backed hydration targets in litres and glasses.
Open calculatorMacro Calculator
Calculate your daily protein, carbohydrate, and fat needs from your calorie target — split macros for cutting, bulking, or recomp in grams and percentages.
Open calculatorWhat you can calculate
Body composition — BMI using WHO category cut-offs (with the South Asian-specific tighter ranges where applicable), body fat percentage using the US Navy circumference method, ideal weight using Devine/Hamwi/Robinson formulas. Each lets you compare across systems and pick the one that matches your context.
Energy needs — BMR (basal metabolic rate) via Mifflin-St Jeor (the most accurate equation per ADA), TDEE (total daily energy expenditure) using activity multipliers, and macros (carbs/protein/fat split) for weight loss, maintenance, or muscle gain.
Hydration and lifestyle — daily water intake based on body weight and activity, calorie targets for specific weight goals at sustainable rates. All formulas are general clinical guidelines — combine with professional medical advice for specific health conditions.
Why these formulas
Most consumer fitness apps use simplified rules of thumb (e.g., '8 glasses of water', 'eat 2000 calories'). Our calculators use the formulas published in clinical journals and adopted by professional dietitians — Mifflin-St Jeor for BMR (validated against indirect calorimetry), the US Navy circumference method for body fat (correlates ~3% with DEXA), and Devine for ideal weight.
These aren't perfect — no formula is. But they're more accurate than generic recommendations and match what a registered dietitian would compute. For complex situations (pregnancy, athletes, medical conditions), supplement with personalised advice.
Frequently asked questions
Is BMI accurate for Indians?
BMI is a population-level screening tool — useful but imperfect for individuals. Indian and South Asian populations show cardiometabolic risk at lower BMIs than the WHO standard categories suggest. Many Indian doctors use a tighter healthy range (18.5-22.9) instead of WHO's 18.5-24.9. Our calculator notes this in the BMI calculator's disclaimer.
Which BMR formula is most accurate?
Mifflin-St Jeor (1990) is consistently the most accurate for the general adult population, validated against indirect calorimetry. We use it as the default. Harris-Benedict (older, 1919, revised 1984) tends to over-estimate by 5-10%. Katch-McArdle is more accurate if you know your body fat percentage.
How much water should I really drink?
The '8 glasses' rule is a rough average. Actual needs depend on body weight, activity level, climate, and diet (fluid from food counts). The water intake calculator estimates ~30-35 ml/kg of body weight, adjusted for activity — typically 2.5-3.5L for an average adult. Listen to thirst and urine colour as honest indicators.
Are these calculators medical advice?
No. Calculators provide general estimates based on standard clinical formulas. They don't account for medical conditions, medications, pregnancy, or individual variations. For health decisions, consult a registered dietitian, sports nutritionist, or physician. The calculators are a starting point, not a substitute for professional advice.
How accurate is body fat percentage from circumference measurements?
The US Navy method (using neck, waist, and hip measurements) typically tracks within ±3-4% of DEXA scan results — accurate enough for tracking changes over time, but not for clinical diagnosis. For exact body fat, use a DEXA scan (~₹3,000-5,000) or BIA-based smart scale (within ±5-7%).
Can I trust calorie targets for weight loss?
The math (calorie deficit = weight loss) is solid. The challenge is execution — actual calorie intake is hard to measure precisely (food labels can be off ±20%), and metabolism adapts to long-term deficits. Use the calorie calculator's target as a starting point; adjust based on actual weight changes over 4-week periods.
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