Health & Fitness Calculators
Estimate your body metrics and energy needs — instantly and privately.
These free health and fitness calculators turn a few measurements into the numbers that actually guide training and nutrition: your BMI, the calories you burn, your body fat percentage, and the macros to hit your goal. Each one shows its formula and a worked example, so you can trust the result rather than take it on faith.
Every calculation runs entirely in your browser — your height, weight, and other details never touch a server. Use them as well-informed starting points, and pair them with the in-depth guides linked below to understand what each number means.
7 health & fitness calculators
BMI Calculator
Calculate body mass index from height and weight (metric or imperial).
TDEE Calculator
Estimate your daily calorie burn (TDEE) and BMR.
Calorie Calculator
Find your daily calorie target to lose, maintain, or gain weight.
Body Fat Calculator
Estimate your body fat percentage with the U.S. Navy method.
Pace Calculator
Running pace, finish time, and speed — with per-distance splits.
Macro Calculator
Turn your calorie target into daily protein, carb, and fat grams.
Sleep Calculator
Find the best bedtime or wake-up time using 90-minute sleep cycles.
Guides
BMI vs Body Fat Percentage: Which Should You Track?
BMI vs body fat percentage explained: what each measures, where BMI falls short, and when to use which — so you track the number that fits your goal.
3 min read
How to Calculate Body Fat Percentage (3 Methods Compared)
How to calculate body fat percentage: the U.S. Navy tape method, skinfold calipers, and DEXA compared — and why the tape method is good enough.
3 min read
How Many Calories Should I Eat? A Simple Guide
How many calories should you eat a day? Learn how BMR, TDEE, and your goal set your number — and get your personal daily calorie target.
3 min read
How to Calculate BMI (Formula, Chart, and What It Means)
How to calculate BMI in metric and imperial units, with the formula, a worked example (70 kg, 175 cm = 22.9), the WHO category chart, and the limitations of BMI.
5 min read
What Pace Do You Need for a Sub-2-Hour Half Marathon?
To break 2 hours in a half marathon you need to run 5:41/km (9:09/mile). Here's the pace math, a full split table, and how to train for and hold that pace.
4 min read
Understanding BMI: What It Measures and What It Misses
What BMI is, how it's calculated, the standard categories, and — importantly — what BMI doesn't tell you. A clear, honest explainer (not medical advice).
2 min read
Frequently asked questions
Which calculator should I use to lose weight?
Start with the Calorie Calculator to get a daily target for your goal, then the Macro Calculator to split those calories into protein, carbs, and fat. Track body composition over time with the Body Fat Calculator rather than relying on scale weight alone.
How accurate are these health calculators?
They use standard, widely accepted formulas (Mifflin–St Jeor for energy, the U.S. Navy method for body fat, WHO categories for BMI) and are accurate enough to guide decisions and track change. They are estimates, not medical measurements — for clinical figures, consult a professional.
Do these calculators store my measurements?
No. Every calculation happens locally in your browser; nothing you enter is uploaded, logged, or stored on a server.
These calculators provide general estimates for educational use and are not medical advice. Consult a doctor or registered dietitian before making significant changes to your diet, exercise, or health routine.
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