Calculator lineup
Choose the health question you want answered first
Each tool isolates one decision: body composition, calorie planning, metabolic baseline, weight range, or training intensity.
BMI Calculator
Check whether your weight is healthy for your height using the Body Mass Index formula.
BMR & TDEE Calculator
Find out how many calories your body burns at rest and how many you actually burn each day.
Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy tape-measure method, no equipment needed.
Ideal Weight Calculator
See your ideal weight range across four scientific formulas, side by side so you can see where they agree.
Calorie Needs Calculator
Get your personalised daily calorie target based on your activity level and weight goal: maintain, cut, or bulk.
Heart Rate Zones
Find your five training zones so every workout hits the right intensity, from fat burn to peak performance.
Calorie Deficit Calculator
Find your exact daily calorie target, deficit size, and timeline to reach your goal weight safely.
Real formulas. Honest context. No fluff.
Smart Health Calculators is a free set of 7 formula-based health calculators (BMI, BMR, body fat, calories, ideal weight and heart-rate zones), reviewed by a certified dietician. Most health tools give you a number with no explanation. These give you the number, the formula behind it, where it falls short, and a clear next step. No proprietary scores, no forced signup, no guesswork.
BMI, Mifflin-St Jeor, U.S. Navy and Tanaka: published formulas used by clinicians and researchers worldwide.
Every number comes with an explanation of what it means, where the formula has limits, and what to do next.
Calculator inputs never leave your browser. See your numbers instantly, with no account and no data collection.
Our editorial standards
Click any calculator to see the full methodology. Prefer an overview? Visit the About page.
Standard BMI formula with WHO classification ranges.
Mifflin-St Jeor equation with standard activity multipliers.
U.S. Navy circumference method with standard reference ranges.
Devine, Robinson, Miller, and Hamwi formulas side by side.
Activity-adjusted calorie estimates built from BMR inputs.
Tanaka max heart rate estimate with a standard 5-zone model.
Compare paths
Calculators or Full Plan?
Both are useful. Here's what you get with each.
FAQ
Common questions
Are these calculators medically accurate?▼
Yes, our calculators use scientifically validated formulas and methods that are widely accepted in the medical and fitness communities. However, they provide estimates and should not replace professional medical advice.
Is my data private and secure?▼
Absolutely. All calculations are performed locally in your browser. We do not store, transmit, or share any of your personal health information. Your data stays on your device.
What's the difference between the calculators and the full plan?▼
The individual calculators are free, so use them any time, no signup needed. The Complete Plan ($9.99, one-time) combines everything into a single personalised report: your exact calorie target, body fat estimate, heart-rate training zones, a 3-day meal plan, shopping list, and a downloadable PDF.
Do I need to create an account?▼
No account needed for anything. The individual calculators are always free. The Complete Plan is a one-time $9.99 purchase, with no login and no subscription.
Editorial
Latest from the Blog
Evidence-based guides to help you understand your results
Global reach
Numbers you can act on,
trusted around the world.
- Reviewed by Dt. Ananya Mehra, a certified dietician
- Built on CDC, WHO and NHS guidelines
- Free, no signup, and your data stays private