Health & Fitness Calculators

For adults, a BMI between 18.5 and 24.9 is considered healthy. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese. BMI is weight in kg divided by height in meters squared. Use the BMI Calculator for an instant result in metric or imperial.

To lose 1 lb per week, create a 500-calorie daily deficit from your TDEE. Most adults need 1,600–2,400 calories/day depending on age, sex, weight, and activity. Never go below 1,200 cal (women) or 1,500 cal (men) without medical guidance. Use the Calorie / TDEE Calculator for your exact number.

Average BMR is roughly 1,400–1,800 cal/day for women and 1,600–2,200 for men, declining about 2% per decade after 30. The Mifflin-St Jeor equation: (10 x kg) + (6.25 x cm) – (5 x age) + 5 (men) or –161 (women). Use the BMR Calculator for your exact baseline.

The US Navy method uses circumference measurements: neck + abdomen (men), neck + waist + hips (women). Healthy ranges: men 10–20%, women 18–28%. Athletes: 6–13% (men), 14–20% (women). Use the Body Fat Calculator for the Navy method or BMI-based estimate.

Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period. If you know conception date, add 266 days instead. Only about 5% of babies are born exactly on their due date. Use the Pregnancy Due Date Calculator for LMP, conception, or IVF transfer date methods.

A 155 lb person burns roughly 280 calories/hour at 3.5 mph, 350 at 4 mph, and 420 at 4.5 mph. Formula: METs x weight (kg) x hours. Walking METs range from 3.5 (moderate) to 5 (brisk). Use the Calories Burned Calculator for your exact weight and pace.

Devine formula: men: 50 kg + 2.3 kg per inch over 5 ft; women: 45.5 kg + 2.3 kg per inch over 5 ft. A 5’10” man has ideal weight of ~166 lbs. BMI 18.5–24.9 is the broader healthy range. Use the Ideal Weight Calculator to compare multiple formulas side by side.

Ovulation occurs 14 days before your next period, not 14 days after. For a 28-day cycle that is day 14; for a 32-day cycle, day 18. The fertile window is 5 days before ovulation plus ovulation day. Use the Ovulation Calculator with your last period date and average cycle length.

Keep waist circumference less than half your height (waist-to-height ratio below 0.5). Health risks rise above 35 inches for women and 40 inches for men. These thresholds are linked to cardiovascular and metabolic disease. Use the Waist-to-Hip Ratio Calculator for a fuller assessment.

General guidelines: 3.7 liters (125 oz) for men and 2.7 liters (91 oz) for women daily from all sources. Simpler estimate: body weight in lbs divided by 2 = daily oz needed. Add 12 oz per 30 minutes of exercise. Use the Water Intake Calculator for a personalized recommendation.