Health calculators turn a few measurements into the numbers that doctors, dietitians and coaches work with: body mass index, daily energy needs, body-fat estimates, hydration targets and pregnancy dates. They are screening and planning aids. They are not diagnoses, and none of them replaces a conversation with someone who has your full history.
Most of the calorie tools here use the Mifflin-St Jeor equation for resting energy, then multiply by an activity factor to get total daily expenditure. BMI uses the standard adult categories. Pregnancy dates use Naegele's rule, which counts 280 days from the start of the last period. Each of these is a population average, so your own result can sit above or below it.
Weight & Body Composition
Body mass index with weight category
BMI Chart & CalculatorBMI with full category reference
Body Fat CalculatorEstimate body fat percentage
Ideal Weight CalculatorHealthy weight range for your height
Weight Loss CalculatorTimeline to reach a goal weight
Bra Size CalculatorFind your correct bra size
Calories & Nutrition
Daily calorie needs by goal
TDEE CalculatorTotal daily energy expenditure
BMR CalculatorCalories burned at rest
Maintenance Calorie CalculatorCalories to maintain current weight
Calorie Deficit CalculatorDaily calories for weight loss
Macro CalculatorProtein, carbs, and fat targets
Protein CalculatorDaily protein target by weight and goal
Water Intake CalculatorDaily hydration goal
Fitness & Recovery
Calories burned by activity
Pace CalculatorRunning pace, speed & finish time
Steps to Miles CalculatorConvert steps to distance
Heart Rate CalculatorTarget heart rate zones
PFT CalculatorPhysical fitness test scoring
Sleep CalculatorBest bedtime & wake time
BAC CalculatorBlood alcohol content estimate
Pregnancy & Reproductive Health
Week by week milestones
Due Date CalculatorPregnancy due date from LMP
Ovulation CalculatorFertile window estimator
Clinical References
Classify a blood pressure reading
Anion Gap CalculatorSerum anion gap from lab values
A practical order for the calorie tools: start with the BMR Calculator to see resting needs, use the TDEE Calculator to add activity, then use the Calorie Deficit or Maintenance Calorie Calculator for a specific goal. Weigh yourself over two or three weeks and adjust, because the equations predict an average and individuals vary.
If a result worries you, or you are managing a medical condition, take it to a clinician rather than relying on a calculator. The clinical reference tools in particular are for checking arithmetic, not for interpreting results.