Free Health & Fitness Calculators
25 free online health and fitness calculators covering body metrics, calories, macros, running pace, heart rate, strength training and pregnancy dates. Every tool explains the formula it uses and runs entirely in your browser — your health data never leaves your device.
About health calculators
Health and fitness calculators turn a few simple measurements into useful reference numbers — a BMI category, a daily calorie target, a running pace or a training intensity zone. They are educational estimators based on published formulas and population averages, not personalised medical advice.
Each tool on this page states the formula it uses (for example, Mifflin-St Jeor for BMR, US Navy method for body fat), explains its assumptions and provides a worked example so you can double-check the result. If you want more background before using them, start with the BMI guide.
These tools are for general information and education. They are not a substitute for professional medical advice, diagnosis or treatment. Always consult a qualified healthcare professional about your health.
Body Metrics
BMI, body fat, lean mass, ideal weight and related measurements.
BMI Calculator
Calculate body mass index in metric or imperial units with WHO categories.
Body Fat Calculator
Estimate body fat percentage using US Navy or BMI-based formulas.
Lean Body Mass Calculator
Estimate lean body mass and fat mass from weight and body fat.
Body Surface Area Calculator
Estimate body surface area using Du Bois or Mosteller formulas.
Ideal Weight Calculator
Estimate ideal body weight using Devine, Robinson and Miller formulas.
Healthy Weight Range Calculator
Find a healthy weight range for your height using BMI ranges.
Energy & Nutrition
Calories, macronutrients, hydration and metabolic rate.
BMR Calculator
Estimate basal metabolic rate using Mifflin-St Jeor or Harris-Benedict.
TDEE Calculator
Estimate total daily energy expenditure from activity level.
Calorie Calculator
Estimate daily calorie needs for weight loss, maintenance or muscle gain.
Calorie Deficit Calculator
Plan a safe calorie deficit and estimate weight-loss timeline.
Calories Burned Calculator
Estimate calories burned during exercise based on activity and duration.
Macronutrient Calculator
Split daily calories into protein, carbohydrate and fat targets.
Protein Intake Calculator
Estimate daily protein needs based on weight and goal.
Carbohydrate Calculator
Estimate daily carbohydrate needs based on activity and goal.
Fat Intake Calculator
Estimate daily fat intake targets in grams and calories.
Water Intake Estimator
Estimate daily water needs based on weight, activity and climate.
Fitness & Training
Running pace, speed, heart rate zones and strength training.
Pace Calculator
Calculate running or walking pace from distance and time.
Running Speed Calculator
Compute average running speed from distance and time.
Target Heart Rate Calculator
Find target heart-rate zones using the Karvonen method.
One Rep Max Calculator
Estimate your one-rep max using the Epley or Brzycki formula.
Pregnancy & Cycle
Due dates, gestational age, conception and ovulation estimators.
Pregnancy Due Date Calculator
Estimate a pregnancy due date from the last menstrual period or conception.
Pregnancy Week Calculator
Find current pregnancy week and trimester from LMP or due date.
Date of Conception Estimator
Estimate likely conception date from due date or LMP.
Ovulation Date Estimator
Estimate ovulation and fertile window from cycle length.
Sleep Duration Calculator
Find the best bedtimes or wake times based on sleep cycles.
Health Guides
Understand the formulas and metrics behind these tools.
Health Calculator FAQs
Health calculators use widely accepted formulas such as Mifflin-St Jeor and the WHO BMI classification. They provide general estimates and are less accurate for athletes, pregnant individuals, children and people with certain medical conditions.
BMI is a screening tool, not a diagnostic one. It does not distinguish muscle from fat or account for body composition. Use it alongside other measurements and professional advice.
No. Health calculator inputs are processed entirely in your browser and are not sent to any server. Your measurements never leave your device.
The BMR calculator supports Mifflin-St Jeor (recommended) and Harris-Benedict (revised) formulas, so you can compare both if you wish.
No. Pregnancy date estimators use average cycle assumptions and give a statistical due date. They do not replace ultrasound dating or advice from a qualified healthcare professional.
Explore Other Categories
Related tools from other sections of Daily Calculator.