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Health & Sports

BMI, running pace, fitness, and athletic performance calculators

BMI Calculator

Calculate your Body Mass Index (BMI) instantly. Get your WHO classification, healthy weight range, and personalized recommendations.

BMR Calculator (Basal Metabolic Rate)

Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Get personalized calorie targets for weight loss, maintenance, and weight gain.

Body Fat Calculator

Estimate your body fat percentage from neck, waist (and hip for women) using the US Navy circumference method. Get fat mass, lean body mass, and ACE/ACSM healthy ranges.

Calorie Calculator (TDEE & Macros)

Calculate your daily calorie needs and macronutrient targets. Get personalized protein, carbs, and fat goals for weight loss, maintenance, or muscle gain based on your TDEE.

Ovulation Calculator

Estimate your next ovulation date, ASRM 6-day fertile window, and the earliest day a home pregnancy test could read positive. Plan three cycles ahead with a stateless calendar visualization.

Pregnancy Calculator

Calculate your due date, current gestational age, and pregnancy milestones from your last menstrual period, conception date, IVF transfer, or known due date. Buddhist Era dates supported in Thailand.

Running Pace Calculator

Calculate your running pace, time, or distance. Get splits, speed, and race predictions with the Riegel formula.

Sleep Calculator

Find the best time to go to bed or wake up based on sleep cycles. Calculate optimal sleep times for 3 to 6 complete 90-minute cycles.

Social Jet Lag Calculator

Measure your social jet lag in hours, find your chronotype, and get a personalized bedtime fix. Based on the Munich ChronoType Questionnaire (MCTQ).

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Health & Fitness Calculators

Take control of your health with our free, science-based health and fitness calculators. Whether you want to check your body mass index, find out how many calories your body burns at rest, plan your next race pace, or understand your sleep chronotype, our tools give you instant results — no sign-up required.

This category includes calculators for body weight assessment (BMI), daily calorie needs and macronutrients (BMR, Calorie Calculator), running and race planning (Running Pace), body composition (Body Fat), sleep cycle optimization (Sleep Calculator), and social jet lag measurement (Social Jet Lag Calculator).

BMI Calculator — Know Your Body Mass Index

Body Mass Index (BMI) is a simple, internationally recognized measure that relates your weight to your height. Our BMI calculator gives you an instant result, classifies it according to WHO standards (Underweight, Normal, Overweight, Obese), and shows where you fall on the scale.

Enter your height and weight in either metric (cm, kg) or imperial (ft/in, lb) units and get your BMI in seconds. The calculator also shows the healthy weight range for your height, so you have a clear, actionable reference point. BMI is a useful screening tool — and a great starting point for any health conversation with your doctor.

BMR Calculator — Find Your Daily Calorie Needs

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic functions at complete rest — breathing, circulation, and cell production. Knowing your BMR is the foundation for any nutrition plan, whether your goal is weight loss, muscle gain, or maintenance.

Our BMR calculator uses the Mifflin-St Jeor equation — the most accurate formula recommended by nutrition scientists today. Enter your age, sex, height, and weight, then apply an activity multiplier to get your Total Daily Energy Expenditure (TDEE). The result tells you exactly how many calories you need each day based on your lifestyle.

Calorie Calculator — TDEE, Goals, and Macros in One Tool

The Calorie Calculator goes beyond BMR to give you a complete daily nutrition target. It computes your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor formula by default, and automatically switches to the more precise Katch-McArdle formula when you supply your body fat percentage — making it especially accurate for athletes and people tracking body composition.

Once you select a goal — lose weight, maintain, or gain weight — the calculator adjusts your daily calorie target by ±500 kcal and distributes those calories across macronutrients in grams. Choose from four diet presets: Balanced, Low Carb, High Protein, or Keto. Whether you are cutting, bulking, or recomping, this tool gives you the exact numbers you need to follow any evidence-based eating plan.

Running Pace Calculator — Plan Any Race or Training Run

The running pace calculator is your go-to tool for planning any run or race. Enter any two of distance, time, and pace to instantly calculate the third. Toggle between kilometers and miles, choose from standard race distances (5K, 10K, half marathon, marathon), and get detailed split tables for your training.

The calculator also uses the Riegel formula to predict your finish times for other race distances based on your current performance — helping you set realistic goals for your next event.

Social Jet Lag Calculator — Measure Your Chronotype and Sleep Debt

Social jet lag is the mismatch between your biological clock and the sleep schedule imposed by work or school. Our Social Jet Lag Calculator is based on the Munich ChronoType Questionnaire (MCTQ) — the scientific standard developed by chronobiology researchers to measure this mismatch precisely.

Enter your sleep and wake times on free days and work days to find out your chronotype (early bird, intermediate, or night owl), your midpoint of sleep, and exactly how many hours of social jet lag you are accumulating each week. The calculator also provides a personalized bedtime recommendation to help you reduce the gap and feel more rested and alert throughout the day.

Your Health & Athletics Toolkit

Together, these health and fitness calculators give you a comprehensive picture of your body and performance. Use BMI and Body Fat to assess your composition, BMR to establish your resting baseline, the Calorie Calculator to set precise daily calorie and macro targets for your specific goal, the pace calculator to structure your training, and the Social Jet Lag Calculator to align your sleep schedule with your natural chronotype — all in one place, completely free.

We are continuing to build out this category with more health and sports tools. Check back regularly to discover new calculators.

Frequently Asked Questions

What is BMI and how is it calculated?
BMI (Body Mass Index) is calculated by dividing your weight in kilograms by the square of your height in meters (kg/m²). In imperial units, the formula is (weight in lb / height in inches²) × 703. Our calculator handles both unit systems automatically.

What is a healthy BMI range?
According to the World Health Organization, a BMI between 18.5 and 24.9 is considered normal or healthy for adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese.

What is BMR and how is it different from TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to sustain vital functions. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor — it represents the total calories you burn in a day including exercise and daily movement. Our BMR calculator computes both.

Which BMR formula does the calculator use?
Our BMR calculator uses the Mifflin-St Jeor equation, which is widely regarded as the most accurate formula for estimating resting metabolic rate in the general adult population. It takes into account your age, sex, height, and weight.

What does the Calorie Calculator include beyond BMR?
The Calorie Calculator computes your full TDEE (not just resting calories), adjusts it for your goal — lose weight (−500 kcal/day), maintain, or gain weight (+500 kcal/day) — and then breaks down your daily calories into protein, carbohydrate, and fat in grams. You can choose from four diet presets: Balanced, Low Carb, High Protein, and Keto.

What is the difference between Mifflin-St Jeor and Katch-McArdle?
Mifflin-St Jeor estimates BMR from age, sex, height, and weight — it is the standard formula for most people. Katch-McArdle uses lean body mass instead of total weight, which makes it more accurate for athletes or anyone who knows their body fat percentage. The Calorie Calculator automatically applies Katch-McArdle when you provide your body fat percentage, and falls back to Mifflin-St Jeor otherwise.

How many calories should I eat to lose weight?
A common evidence-based approach is to eat 500 kcal per day below your TDEE, which creates a deficit that leads to roughly 0.5 kg (1 lb) of fat loss per week. Our Calorie Calculator computes this target for you automatically when you select the 'Lose weight' goal — and also shows the matching macronutrient split for your chosen diet preset.

What are macronutrients and why do they matter?
Macronutrients — protein, carbohydrates, and fat — are the three main energy sources in food. Each gram of protein and carbohydrate provides 4 kcal; each gram of fat provides 9 kcal. The ratio of macros in your diet affects how you feel, perform, and build or preserve muscle. The Calorie Calculator translates your daily calorie goal into grams of each macro across four presets so you know exactly what to eat.

What is social jet lag?
Social jet lag is the difference in hours between your sleep midpoint on free days (your natural rhythm) and on work or school days (your forced schedule). A social jet lag of 2 hours or more is associated with higher fatigue, increased risk of obesity, and lower academic or work performance. The Social Jet Lag Calculator quantifies this gap and shows your chronotype.

What is a chronotype?
A chronotype is your genetically determined preference for sleep and wake times — whether you are a natural early bird, an intermediate type, or a night owl. The Munich ChronoType Questionnaire (MCTQ) measures chronotype using your sleep midpoint on free days as the key indicator. Knowing your chronotype helps you schedule activities at times when your brain and body are most alert.

Is BMI accurate for everyone?
BMI is a useful general screening tool, but it does not account for muscle mass, bone density, age, or sex. Athletes with high muscle mass may have a high BMI without excess body fat. Always discuss your results with a healthcare professional for a complete health assessment.

Can I use these calculators in both metric and imperial units?
Yes. Both the BMI and BMR calculators fully support metric (centimeters and kilograms) and imperial (feet, inches, and pounds) units. The default is based on your region, but you can switch at any time.

How does the running pace calculator work?
Choose what you want to calculate (distance, time, or pace), enter the other two values, and the calculator instantly shows you the result along with your speed in both km/h and mph, a complete split table, and race predictions using the Riegel formula.

Are these calculators free to use?
Yes, all our health and fitness calculators are completely free with no account or sign-up required. Just open the tool, enter your numbers, and get instant results.