Terms of Use

Q: Can I build my own tool using your formulas?

The underlying equations such as Mifflin-St Jeor, US Navy, Devine, Riegel, Epley and Karvonen are published in the literature and are not owned by us. Implement them freely in your own product, but do not copy our code, explanatory text, or tables.

Q: Can I run these calculators commercially for a client?

You may run them internally to produce your own analysis and you may link to our pages. You may not embed or resell the calculators themselves as part of a service.

Q: Do I need to credit the underlying researchers?

Our pages name the original formulas and link to their sources. Crediting the original study or guideline body such as the WHO, CDC, or ACSM is good scholarly practice and is often required by those publishers' reuse terms.

Q: Is using a free calculator here safe for my health?

The calculators implement published equations accurately, but those equations were built for general screening. Some are less accurate for certain groups. Read the limitations section on each page and consult a qualified professional for anything that affects your health.

These terms govern your use of CalcToolsKit, a free library of fitness and health calculators. By using this site you agree to the terms below. If you do not agree, please do not use the site.

1. License to use the calculators

CalcToolsKit grants you a personal, non-exclusive, non-transferable, royalty-free licence to use the calculators on this site for your own private or internal use. You may run the calculations, read the supporting explanations, print the results for your own records, and share links to the pages with others.

This licence does not transfer ownership. Ownership of the calculators, the formulas they implement, the code that powers them, the explanatory text, and the visual design of the site remain with CalcToolsKit and the original authors of the underlying public-domain equations.

2. Acceptable use

You agree not to:

Scrape, crawl, or harvest the pages, formulas, or calculator code of this site in bulk, whether by automated tools or by systematic manual copying, in a way that competes with or substitutes for the site itself.
Republish, mirror, or redistribute whole pages — including the explanatory content, tables, and worked examples — on another site, whether modified or unmodified.
Present our calculator results as your own proprietary calculation engine, or use our code inside a competing product.
Attempt to interfere with the operation of the site, including introducing malicious code, overloading the server, or circumventing rate limits.
Use the site in any way that violates applicable law.

You may link to any page on this site from your own content. You may not, however, use automated means to submit pages for indexing on behalf of a third-party site.

3. No medical, legal, or professional advice

The calculators on this site are educational tools. They produce mathematical estimates based on published population equations. They do not constitute medical, nutritional, legal, financial, or other professional advice, and they are not a substitute for advice from a qualified professional who knows your individual circumstances.

Never use a result from this site to diagnose a condition, to start or stop a medication, to prescribe a diet, or to make a clinical decision. Some of the equations we use were developed for population-level screening rather than for individual diagnosis. Always speak with a physician, registered dietitian, or other qualified professional before changing your health routine.

4. Accuracy of results

We implement widely published equations such as the Mifflin-St Jeor energy model, the US Navy body-composition method, Devine and related muscle-mass coefficients, the Riegel running formula, and the Epley and Brzycki strength models. Each page documents the equation it uses and its known limitations. We correct errors when we find them, but we make no guarantee that any result is accurate, complete, or suitable for a particular purpose.

If you believe a calculator produces a wrong result, please tell us — corrections are genuinely welcome.

5. Availability and changes

We may change, suspend, or retire any calculator, and we may update these terms, at any time and without notice. We do not promise that the site will always be available or error-free, and we may discontinue it entirely.

6. Intellectual property

The name CalcToolsKit, the site's layout and design, and the original explanatory text we have written are our property and are protected by copyright. Underlying equations and public-health reference data (for example WHO body mass index thresholds and CDC child growth-chart percentile tables) remain the property of their original publishers and are cited on the relevant pages. Where we quote or reproduce such material we do so under the terms their publishers permit.

If you believe something on this site infringes your rights, please contact us and we will address the issue promptly.

7. Limitation of liability

To the maximum extent permitted by law, CalcToolsKit and its operators are not liable for any indirect, incidental, special, consequential, or punitive damages, and for any loss of profits, data, health, or opportunity, arising out of or in connection with your use of this site — even if we have been advised of the possibility of such damages. Any liability that cannot lawfully be excluded is limited to the greater of the amount you paid us (which is zero) or the minimum permitted by law.

8. Third-party links and advertising

This site contains links to third-party resources and displays advertising served by Google AdSense. We do not control and are not responsible for the content, products, services, or privacy practices of any third party. Following an external link is at your own risk. How we use advertising cookies is described in our Privacy Policy.

9. Changes to these terms

We may revise these terms from time to time. The version published on this page is the version that applies. Continued use of the site after a revision constitutes acceptance of the revised terms.

10. Contact

Questions about these terms can be sent to us through our contact page.

Last updated: October 2026. Plain-language summary: you may use our calculators freely for personal use and link to our pages, but you may not copy the site wholesale or republish it as your own.

Common questions about these terms

Can I use CalcToolsKit results in my own article or video?

Yes. You may quote the results and summarise what the formulas mean, provided you do not reproduce our pages wholesale or present the calculator itself as your own. For clarity, a link back to the relevant calculator page is appreciated but not required.

Can I build my own tool using your formulas?

The underlying equations — Mifflin-St Jeor, US Navy circumference method, Devine coefficients, Riegel, Epley, Karvonen and so on — are published in the scientific and clinical literature and are not owned by us. You are free to implement them in your own product. You may not, however, copy our code, our explanatory text, or our tables.

Can I run these calculators commercially for a client?

You may run them internally to produce your own analysis, and you may link to our pages. You may not embed or resell the calculators themselves as part of a service. If you want that kind of integration, get in touch so we can work something out.

Do I need to credit the underlying researchers?

Our pages name the original formulas and link to the relevant sources. If you write about the results, crediting the original study or the guideline body — the WHO, the CDC, or the ACSM, for instance — is good scholarly practice and is often required by those publishers' reuse terms.

What happens if you change these terms?

We will revise this page and update the date at the bottom. Material changes will be visible here. Because the terms grant you a licence rather than imposing obligations on your daily use, a revision never affects results you already calculated.

Is using a free calculator here safe for my health?

The calculators are accurate implementations of published equations, but the equations themselves were built for general screening. Some are known to be less accurate for certain groups — for example the US Navy body-fat method assumes a specific bone width, and BMI ignores muscle mass entirely. Read the limitations section on each calculator page. For anything that affects your health, get advice from a qualified professional who can see your full picture.