About Health & Fitness calculators
Most health targets - daily calories, macros, body fat, heart-rate zones, pregnancy due dates - are based on published clinical formulas, not guesswork. Knowing your number from the right formula gives you a real baseline to work from rather than a rough estimate. Our health calculators use the standard equations from sports science and clinical medicine: Mifflin-St Jeor for BMR, the US Navy tape-test method for body fat, Naegele's rule for due dates, and Karvonen for heart-rate zones. For Indian users, BMI thresholds follow WHO Asia-Pacific guidelines (overweight at ≥23, obese at ≥25) rather than the global standard - both are shown side by side so you can see where you stand under each.
Choosing the right fitness calculator
If you're starting a fat-loss or muscle-gain journey, sequence matters: BMI gives you a quick category, BMR gives you the resting baseline, TDEE multiplies that by activity, and the calorie + macro calculators turn TDEE into a daily plate. For runners and cyclists the pace, heart-rate, and calories-burned calculators are the daily tools. For pregnancy, the due-date, conception, ovulation, and pregnancy-weight-gain calculators cover the entire 40-week timeline. Each tool clarifies what it can and cannot do - none of these replace a doctor, registered dietitian, or certified trainer.
Why Indian cut-offs differ
WHO Asia-Pacific guidelines lower the BMI thresholds for overweight (≥23) and obesity (≥25) because South Asians develop metabolic risk at lower BMIs than Europeans. Our BMI tool shows both global and Indian categories side by side. Body-fat formulas (US Navy, deurenberg) are the same worldwide; pregnancy weight-gain ranges follow IOM 2009. Heart-rate zones are age-based and culture-neutral.
Privacy and accuracy
All inputs stay on your device. Numbers are point estimates - body fat from skinfolds or US Navy method has a ±3% standard error compared to a DEXA scan. BMR can vary ±10% person to person at the same height and weight. Use these tools to track trends week over week, not to chase decimal precision day to day.