Health & Fitness calculators
BMI, calories, body fat and daily wellness math.
These calculators give you informational numbers about weight, body composition, and daily energy needs — none of them diagnose anything, and all of them are simplified formulas with known limitations, which each calculator's own page explains.
They roughly split into body composition (BMI, Body Fat, Ideal Weight), energy and activity (BMR, Calorie, Heart Rate Zones, Water Intake), and one specific to pregnancy timing.
BMI Calculator
Free BMI Calculator to calculate your Body Mass Index (BMI) using your height and weight. Check your healthy weight range instantly.
BMR Calculator
Free BMR Calculator. Calculate your Basal Metabolic Rate (BMR), resting calorie burn, and estimated daily calorie requirements accurately.
Body Fat Calculator
Free Body Fat Calculator. Calculate your body fat percentage using the U.S. Navy method and check your body fat category instantly.
Calorie Calculator
Free Calorie Calculator to estimate your daily calorie needs for maintaining, losing, or gaining weight based on your age, height, weight, and activity level.
Water Intake Calculator
Free Water Intake Calculator to estimate your daily water intake based on your weight, activity level, and lifestyle for proper hydration.
Pregnancy Due Date Calculator
Free Pregnancy Due Date Calculator to estimate your baby's due date, current pregnancy week, and trimester based on your last menstrual period (LMP).
Ideal Weight Calculator
Free Ideal Weight Calculator using the Devine formula to estimate a reference body weight range from your height and sex.
Heart Rate Zone Calculator
Free Heart Rate Zone Calculator to estimate your maximum heart rate and target zones for fat burn, cardio, and peak-effort training by age.
How to choose the right calculator
- A quick population-level weight screening → BMI Calculator
- Calories burned at rest, as a baseline for a diet plan → BMR Calculator
- Daily calorie target to lose, gain, or maintain weight → Calorie Calculator
- Estimated body-fat percentage from tape measurements → Body Fat Calculator
- A reference body-weight range from height → Ideal Weight Calculator
- Training heart-rate zones by age → Heart Rate Zone Calculator
- A rough daily water intake target → Water Intake Calculator
- Estimated due date from last menstrual period → Pregnancy Due Date Calculator
Frequently asked questions
BMI only uses height and weight, so it can't tell muscle from fat — a muscular person can show a high BMI while having low body fat. Body Fat Calculator estimates composition more directly, which is why the two numbers can point in different directions for the same person.
No. Every calculator in this category is informational only, using standard published formulas — none of them replace an actual medical evaluation. Each calculator's own page states its specific limitations.
BMR Calculator gives you the resting baseline, and Calorie Calculator builds on that with your activity level to suggest a daily target — used together they cover the two questions a diet plan usually starts with.