Free health calculators for BMI, TDEE, BMR, calorie needs, body fat, ideal weight, blood pressure, sleep, water intake, pregnancy, and fitness. WHO and ICMR guidelines.
Every calculator on iCalcApp is free with no sign-up, and no data collection. Calculations run instantly in your browser — your inputs are never sent to our servers.
All formulas are reviewed by Mayra, and cross-verified against official sources (RBI, WHO, ICMR, ISO).
iCalcApp health calculators cover BMI, TDEE, calories, macros, BMR, body fat, heart rate, blood pressure, pregnancy, and 10 more. All formulas are based on WHO, NIH, and AHA guidelines. Free, instant, no signup required.
All health calculators on iCalcApp use formulas from peer-reviewed research and authoritative guidelines: Mifflin-St Jeor equation for BMR (1990), WHO BMI thresholds (2000), US Navy body fat method (Hodgdon & Beckett, 1984), Tanaka maximum heart rate formula (2001), and NIH water intake references (2004 DRI Report). Each calculator page cites its specific source.
For a complete fitness picture: BMI Calculator (body composition screening), TDEE Calculator (daily energy needs), Body Fat Calculator (accurate composition), Heart Rate Calculator (training zones), and Protein Calculator (muscle-building targets). Track these monthly rather than daily for meaningful trend data.
The health set covers body metrics, energy, and lifestyle planning. Start with the blood pressure calculator, BMI calculator, BMI calculator kg cm, BMR calculator, body fat calculator, calorie calculator, calorie deficit calculator, due date calculator, heart rate calculator, ideal weight calculator, macro calculator, ovulation calculator, pace calculator, pregnancy calculator, protein calculator, running calorie calculator, sleep calculator, steps to calories calculator, TDEE calculator, vitamin d calculator, and the water intake calculator. Each opens instantly, calculates in real time as you type, and explains its formula with worked examples below the tool.
Start with the TDEE Calculator to find how many calories you burn daily. Then use the Calorie Deficit Calculator to set a safe daily target (500 kcal below TDEE for 0.5 kg/week loss). Follow up with the Macro Calculator to split your calories into protein, carbs, and fat targets.
The BMI Calculator uses the WHO formula (weight ÷ height²) and applies both WHO global and Indian-specific thresholds (overweight at 23, obese at 27.5 for South Asians). BMI is accurate for population-level screening but does not measure body fat directly — see the Body Fat Calculator for a more precise individual assessment.
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to maintain organ function. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor. A sedentary person's TDEE is BMR × 1.2. An athlete training twice daily: BMR × 1.9. TDEE is the number to use for any diet or fitness plan.
Use the TDEE Calculator if you want the most accurate daily calorie burn estimate — it uses the Mifflin-St Jeor equation and your activity level. Use the Calorie Calculator for a quick goal-based target (lose weight, maintain, or gain muscle) with recommended macro splits.
These calculators provide general population estimates based on standard formulas. People with diabetes, kidney disease, eating disorders, pregnancy complications, or cardiac conditions should consult their doctor or dietitian before using calculator outputs to guide diet or exercise decisions.
Sources: WHO Global Health Observatory; National Institutes of Health (NIH) dietary reference intakes; American College of Sports Medicine guidelines; ACOG obstetric guidelines.
For the statistics behind health metrics, see our math calculators.
From our blog: Fitness Metrics Guide · Daily Calorie Guide
For users who prefer metric inputs, the BMI calculator (kg and cm) uses kilograms and centimetres directly — with Asian/South Asian BMI cutoffs for Indian users.
Health disclaimer: All health calculators provide estimates for educational and informational purposes only. Results are not medical diagnoses. Always consult a qualified healthcare professional for medical decisions. iCalcApp health pages are reviewed by Dr. P Nair, MBBS, MD.
The BMI calculator uses weight and height to classify weight status — with both WHO and Asian (South Asian) cutoff thresholds. The BMI calculator (kg and cm) accepts metric inputs directly. The body fat calculator uses the Navy method (waist, neck, height measurements) for a more accurate fat percentage. The ideal weight calculator provides target weight from multiple established formulas.
Start with the calorie calculator for your daily energy needs. The BMR calculator gives your resting metabolic rate (Mifflin-St Jeor equation). Multiply by an activity factor with the TDEE calculator for your total daily expenditure. The calorie deficit calculator sets your weight loss calorie target. The macro calculator divides your calories into protein, carbs, and fat. The protein calculator gives your daily protein target for muscle gain or fat loss. The water intake calculator personalises your daily hydration goal.
The heart rate calculator provides all five training zones using the Karvonen formula. The pace calculator converts between running speed, pace, and finish time. The steps to calories calculator estimates calories from daily step count. The running calorie calculator estimates burn by distance, pace, and body weight. The sleep calculator finds the optimal bedtime based on 90-minute sleep cycles.
The blood pressure calculator classifies BP readings using WHO and ISH 2020 guidelines. The vitamin D calculator estimates your daily vitamin D synthesis from sunlight and diet.
The pregnancy calculator estimates the due date from LMP or conception date. The due date calculator provides a week-by-week pregnancy timeline. The ovulation calculator identifies the fertile window from cycle length.
| Goal | Best Calculator |
|---|---|
| Check healthy weight for height | BMI Calculator + Ideal Weight Calculator |
| Find daily calorie target | TDEE Calculator |
| Plan weight loss calories | Calorie Deficit Calculator |
| Calculate daily protein need | Protein Calculator |
| Find heart rate training zones | Heart Rate Calculator |
| Understand blood pressure reading | Blood Pressure Calculator |
| Calculate pregnancy due date | Due Date Calculator |
Further reading: Daily Calorie Needs Guide · Fitness Metrics Guide · BMI Limitations · Body Fat % Guide