Free Health & Fitness Calculators
Seven science-backed calculators for weight, metabolism, body composition and hydration — instant, private, metric & imperial. Includes BMI, BMR, body fat, calorie/TDEE, ideal weight, water intake and pregnancy due date.
How to use the Health Calculators
- Pick your calculator: Choose from BMI, BMR, body fat, calorie, ideal weight, water intake or pregnancy due date.
- Enter your details: Select metric or imperial units and enter your height, weight, age and other inputs.
- Read your result: See your instant result, category and guidance, processed privately in your browser.
Frequently Asked Questions
What are the best free health calculators?
FixFlowHub offers seven free health calculators: BMI, BMR, body fat %, calorie/TDEE, ideal weight, water intake and pregnancy due date. All are free, need no sign-up, and run privately in your browser.
Which health calculator should I use to lose weight?
Start with the Calorie Calculator for your daily target and deficit, then track Body Fat % and BMR to preserve muscle while losing fat.
Are online health calculators accurate?
They use peer-reviewed formulas and are accurate to roughly ±5–15% as screening tools — great for goal-setting, but not a substitute for medical testing.
Do these calculators support metric and imperial units?
Yes — every calculator except pregnancy dating supports kg/cm and lb/ft-in.
Is my data private?
Yes. All calculations run client-side in your browser; no inputs are uploaded or stored.