Health
Make smarter health decisions
Calculators, decision guides, and planners for your health and wellness
Free health calculators and decision guides for the numbers that matter — BMI, daily calories, macros, body fat, sleep, and hydration. Each calculator gives an instant reading, and the guides help you decide what to do with it: whether your weight is actually a problem, whether you're eating enough protein, and how much sleep you really need. These tools are for screening and education — for personal medical advice, talk to a healthcare professional.
Health Hub
Your body, in numbers you can act on
17 health calculators, 17 interactive guides, and 15plain-English articles — organized by what you're trying to figure out, not by tool type. Every result is computed live in your browser, with zero signups and zero data collection.
Live body snapshot · no signup
Four numbers in ten seconds
BMI
25.1
Overweight
BMR (resting)
1,696 cal/day
Mifflin-St Jeor
Water target
91 fl oz/day
~35 ml per kg
Protein target
93 g/day
1.2 g/kg (active)
What brings you here?
💪
Manage my weight
Know where you stand, then decide what to do about it
Calculators
Guides & quizzes
🥗
Eat smarter
Macros, protein, water — the inputs you control every day
Calculators
Guides & quizzes
😴
Sleep better
Work backward from when you need to wake up
Calculators
Guides & quizzes
👶
Plan a pregnancy
From trying to conceive to tracking each trimester
Calculators
Guides & quizzes
❤️
Train & perform
Heart-rate zones, calories burned, and honest recovery
Calculators
Guides & quizzes
🔥
Understand my body
What your metabolism is actually doing — and whether that's normal
Calculators
Guides & quizzes
All 17 health calculators
BAC Calculator
Estimate your blood alcohol concentration using the Widmark formula. See impairment level and time to sober up.
BMI Calculator
Calculate your Body Mass Index and find out your weight category with a visual range indicator.
BMR Calculator
Calculate your Basal Metabolic Rate with the Mifflin-St Jeor equation. See your TDEE across 5 activity levels.
Body Fat Calculator
Estimate your body fat percentage using the US Navy method with measurements for waist, neck, and height.
Body Roundness Index Calculator
Calculate your Body Roundness Index (BRI) from height and waist — the BMI alternative that measures where you carry weight.
Calorie Calculator
Calculate your daily calorie needs using the Mifflin-St Jeor equation. Get BMR, TDEE, and calorie targets.
Calories Burned Calculator
Estimate calories burned during any activity using MET values. See food equivalents and walking step conversions.
Ideal Weight Calculator
Find your ideal weight range using multiple formulas including Devine, Robinson, Miller, and Hamwi with BMI context.
Lean Body Mass Calculator
Estimate your lean body mass using the Boer, James, and Hume formulas. See body fat percentage and lean vs fat mass breakdown.
Macros Calculator
Calculate your ideal macronutrient split for cutting, maintaining, or bulking. Get personalized protein, carb, and fat targets in grams.
Ovulation Calculator
Predict your ovulation date, fertile window, and most fertile days for up to 3 upcoming cycles based on your menstrual cycle.
Pregnancy Due Date Calculator
Calculate your estimated due date based on last menstrual period or conception date with trimester breakdown.
Pregnancy Weight Gain Calculator
Get personalized weight gain recommendations based on IOM guidelines, pre-pregnancy BMI, and current week of pregnancy.
Protein Calculator
Calculate your daily protein needs based on weight, activity level, and fitness goal. Get per-meal breakdowns and protein source references.
Sleep Calculator
Find the perfect bedtime or wake-up time based on 90-minute sleep cycles. Wake up refreshed by aligning with your natural rhythm.
Target Heart Rate Calculator
Calculate your five heart rate training zones in bpm — Karvonen or % of max HR, personalized with your resting heart rate.
Water Intake Calculator
Calculate how much water you should drink daily based on your weight, activity level, climate, and exercise.
Learn
How to Calculate Body Fat Percentage
ARTICLEHow to Calculate Ideal Weight
ARTICLEBMI for Kids
ARTICLEBMI: What It Measures & Misses
ARTICLEHow Many Calories Does Exercise Burn?
ARTICLETDEE & Calorie Guide
ARTICLEHow Much Protein Do You Need Per Day?
ARTICLEHow to Calculate Macros for Cutting & Bulking
ARTICLEHow to Calculate Lean Body Mass
ARTICLEWhat Is BMR and How to Calculate It?
ARTICLEHow to Estimate Blood Alcohol Content
ARTICLEHow Much Weight Should You Gain During Pregnancy?
ARTICLEHow to Calculate Ovulation and Fertile Window
ARTICLEHow Much Water Should You Drink Daily?
ARTICLESleep Cycle Calculator: How Sleep Works