Accurate by Design
Mifflin–St Jeor, Katch–McArdle, US Navy body-fat and more — implemented carefully and validated with test suites.
Smart, Accurate & Science-Based Health Tools
Free Fitness Calculators Instantly calculate BMI, TDEE, Body Fat, and more — built for athletes, trainers, and everyday people who value precision and clarity.
- AI-assisted insights
- 36+ Health & fitness tools
- Science-backed formulas
Why Choose Free Fitness Calculators?
We turn complex physiology and nutrition science into clean, reliable calculators — so you can make better decisions, faster.
Readable Results
Clear ranges, contextual tips, and “what this means” summaries so you can act with confidence.
Smart Enhancements
Gentle AI logic to adapt recommendations to input patterns — never replacing evidence, only clarifying it.
Free & Transparent
No paywalls. No gimmicks. Just fast tools, clear methods, and links to our reference guides.
Ad Space — Leaderboard (970x90)
Popular Fitness Calculators
The most-searched, most-used tools — each built on validated formulas and reviewed for clarity.
BMI Calculator
See BMI and healthy weight ranges by height and sex.
Calorie Calculator
Estimate maintenance, deficit, and surplus targets.
Body Fat %
US Navy & BMI methods with category interpretation.
Ideal Weight
Devine, Hamwi, Robinson and more — side-by-side.
TDEE
Total Daily Energy Expenditure by activity level.
BMR
Basal Metabolic Rate via Mifflin–St Jeor or Katch.
Heart Rate Zones
Fat burn, cardio and endurance zones by age & max HR.
Sleep Time
Best bed/wake times aligned to sleep cycles.
Ad Space — Leaderboard (970x90)
Explore More Tools & Guides
Take your training and nutrition to the next level with calculators, evidence-based articles, and simple explanations you can actually use.