About Smart Health Calculators
Free health tools built on published research, explained in plain English. No sign-ups, no data stored on our servers, no noise.
Why we built this
Most health calculators online are either buried under ads, require you to create an account, or give you a number with no explanation of what it means or how to use it.
We wanted something different: clean tools that are fast to use, built on the same formulas used in clinical and research settings, and paired with honest explanations of what the numbers actually mean and what their limitations are.
We also wanted every calculator to answer the follow-up questions people actually have. Not just “your BMR is 1,520”, but what that means, how to use it, what affects it, and what to do next.
What our calculators are based on
Every calculator on this site uses established formulas from published research. We do not use proprietary or invented methods. Here is what each tool is based on:
Standard BMI formula (weight kg / height m squared). WHO classification thresholds.
Mifflin-St Jeor equation (1990). Activity multipliers from the Harris-Benedict framework.
U.S. Navy circumference method. Cross-referenced with ACE and ACSM body fat classification ranges.
Devine formula (1974), Robinson formula (1983), Miller formula (1983), and Hamwi formula (1964).
Mifflin-St Jeor BMR with activity-adjusted TDEE. Macro splits based on general dietary reference intake guidelines.
Maximum heart rate estimated using the Tanaka formula (2001). Zone percentages based on standard 5-zone training model.
How we write our guides
Each article on this site is written to one standard: explain the topic clearly and honestly, including where the science is uncertain or where a metric has real limitations.
- We link to primary sources (PubMed, WHO, major health organisations) when citing specific claims.
- We explain the limitations of every formula we use. No single metric tells the full story.
- We do not exaggerate what a calculator result means, or imply it is a medical diagnosis.
- We update articles when guidance changes or when we find better sources.
- We do not recommend specific diets, supplements, or products.
A note on medical advice
Our calculators and articles are for informational and educational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment.
If you have a health condition, are taking medication, are pregnant, or have any concern about a result you get from one of our tools, please speak with a qualified healthcare provider before making changes to your diet, exercise routine, or lifestyle.
Read our full medical disclaimerYour data and privacy
All calculations happen in your browser. We do not store your height, weight, age, or any other personal health data on our servers. When you close the page, that data is gone.
We use basic analytics to understand how many people visit the site and which pages are most useful, but we do not track individuals or sell data. For full details, see our Privacy Policy.
Get in touch
If you spot an error, have a suggestion for a new calculator or article, or just want to say something, you can reach us at:
smarthealthcalculators@gmail.com