Health & Fitness
Energy needs, body metrics, movement, and planning tools — with transparent math.
Health numbers can guide habits, but they are not diagnoses. These calculators translate common formulas—BMI, intake and burn estimates, activity-adjusted energy needs, stride-based step counts, board volume, and calendar-based due-date rules—into quick answers while showing what went into them. Always confirm anything medical with a licensed clinician, especially in pregnancy or when changing diet or exercise.
BMI & body fat
Screening-style metrics from height, weight, and sometimes circumference—useful for trends, not single-point judgments.
Intake & burn
Calorie targets and burn estimates connect food, movement, and optional activity factors—interpret ranges, not false precision.
Steps & boards
Stride drives steps per mile; surfboard volume translates dimensions into liters for gear choices.
Due dates
Estimated delivery windows from LMP or similar inputs follow rule-of-thumb obstetric dating—not ultrasound replacements.
Calculators
View all health & fitness toolsBMI Calculator
Body Mass Index from height and weight—compare to common reference bands and note athlete/limitations context.
Body Fat
Estimate body-fat percentage from measurements using established regression-style formulas—results vary by method.
Calorie Calculator
Daily calorie targets from demographics, activity, and weight-change goals using standard predictive equations.
Calories Burned
Approximate energy expenditure for activities using metabolic equivalents and duration.
Doomscrolling Cost
Turn passive screen time into annual days scrolling, opportunity cost, sleep impact, and per-app breakdowns.
Due Date Calculator
Estimated due date from last menstrual period or similar—always follow your clinician’s dating plan.
TDEE Calculator
Total Daily Energy Expenditure by multiplying a basal estimate by an activity factor you select.
Steps in a Mile
Translate height and pace into approximate steps per mile for trackers and training estimates.
Surfboard Volume
Compute board volume from length, width, thickness, and shape assumptions—compare quiver sizing.
Guides & Articles
View all Health & Fitness articles
What Is BMR Calculation? Your Weight Management Guide
Discover what is BMR calculation and how it impacts your weight management. Learn to calculate your calorie needs for effective dieting!
Why Use Workout Calculators to Optimize Your Training
Discover why use workout calculators to optimize your training. Achieve your fitness goals with structured, data-driven plans that enhance results.
Top 4 Best Body Fat Analyzer Tools 2026
Discover the top 4 best body fat analyzer tools to help you compare and decide which is the best fit for your health and fitness goals.
Types of health calculators: your complete guide
Discover the types of health calculators available today. This complete guide helps you choose the right tool for your health needs!
Why broccoli makes your gas smell and what to do
Wondering why do my farts smell like broccoli? Discover the science behind broccoli-scented gas and get tips to manage the odor effectively!
How to estimate body fat: Practical methods that work
Discover how to estimate body fat accurately with practical methods that reveal your true health progress. Take control of your fitness journey!
Understanding your basal metabolic rate for better results
Discover what is basal metabolic rate and how understanding it can optimize your weight and fitness goals for better results!
How compound interest fuels long-term fitness gains
Discover what is compound interest in fitness and how small, consistent actions can lead to transformative, long-term fitness gains.
How Many Steps a Day Do You Actually Need? It's Not 10,000 - And the Science Behind That Number Will Surprise You
The 10,000-step goal wasn't created by doctors or researchers. It was invented to sell pedometers. The most comprehensive scientific review ever conducted has arrived at a very different, and far more forgiving, number.
Surfboard Volume Explained: Complete Guide to Choosing the Right Liters (2026)
Learn what surfboard volume means, why liters matter more than length, how to use the GF ratio, and how to avoid the most common volume mistakes when buying a board.
Formula Quick Reference
Typical equations behind these tools—your clinician or coach may use different constants or cutoffs than any generic website.
| Formula | Equation | Variables | Result unit | Calculator |
|---|---|---|---|---|
| Body Mass Index | BMI = mass / height² | kg & m, or imperial equivalents | kg/m² | Use calculator → |
| Mifflin–St Jeor (BMR) | BMR = f(sex, weight, height, age) | predictive resting expenditure | kcal/day | Use calculator → |
| TDEE | TDEE ≈ BMR × activity factor | factor reflects weekly movement level | kcal/day | Use calculator → |
| Activity energy | kcal ≈ MET × kg × hours | MET tables vary by source | kcal | Use calculator → |
| Scrolling opportunity cost | cost ≈ daily_scroll_hrs × 365 × $/hr | passive % or per-app type weights | USD/yr | Use calculator → |
| Estimated due date | EDD ≈ LMP + 280 days | rule-of-thumb obstetric dating | calendar date | Use calculator → |
| Steps per mile | steps/mi ≈ 5280 / stride(ft) | stride from height/pace assumptions | steps | Use calculator → |
| Surfboard volume | liters from L × W × thickness | shape corrections inside tool | L | Use calculator → |
| Body fat estimate | regression on measurements | e.g., waist, neck, hip per method | % | Use calculator → |
Watch & Learn
Short explainers on BMI math, what food calories represent, and how energy in food is measured—general education, not individualized guidance.
Calculate BMI - The Body Mass Index Formula
Walkthrough of the BMI ratio—pairs well with entering height and weight in our BMI Calculator.
The Deal with Calories | Crossover with SciShow's The Deal with Fat
What “calories” measure in food—helpful intuition behind intake targets and burn estimates.
We 🔥Burned🔥 Food to Figure Out How Many Calories It Has
How food energy is measured in the lab—context for calorie labels and calculator outputs.
Frequently Asked Questions
BMI, energy equations, due dates, and how to interpret calculator output responsibly.