Editorial Policy & Methodology
How the calculators and articles on Sport Calculator are built, sourced, tested, updated and corrected, and how the site is funded.
By Jonas Lindemann · Updated
Who writes and builds the site
Sport Calculator is built and written by Jonas Lindemann, a software developer and endurance athlete from Hamburg, Germany (cycling since 2014, running since 2016, triathlon since 2020). Jonas is not a physician, dietitian or certified coach, and the site does not claim otherwise. That is why every calculator is built on published, citable formulas rather than personal opinion, and why each one explains its method on the page.
If a qualified professional (for example a registered dietitian or exercise physiologist) reviews a page, their name, credentials and a link to their profile are shown as “Reviewed by” on that page. Pages without that line have not had an external expert review.
How calculators are built
Every calculator starts from a published source: a peer-reviewed equation, an official standard or a widely used reference table. Examples of the sources we use:
- Compendium of Physical Activities (Ainsworth et al.; 2024 adult update: Herrmann et al.): MET values for calorie calculators across hundreds of sports and everyday activities
- ACSM's Guidelines for Exercise Testing and Prescription (metabolic equations): Walking, running, cycling and stepping energy equations (treadmill, StairMaster, bike)
- Daniels' Running Formula (Jack Daniels): VDOT, race-time predictions and training paces
- Mifflin-St Jeor equation (Mifflin et al., 1990): Basal metabolic rate, TDEE and calorie targets
- Keytel et al. (2005), heart-rate-based energy expenditure: Calorie estimates from average heart rate
- Tanaka, Monahan & Seals (2001), age-predicted maximal heart rate: Maximum heart rate and heart-rate zones
Official test standards (for example military fitness tests or governing-body rules such as USBC bowling scoring) are implemented from the published scoring tables of the organisation that owns them. Each calculator page has a “How it works” or methodology section that names the formula, shows it, and states its limitations. A broader overview of the research and scientists behind the tools is on Our Science.
Where sources disagree, we pick the one that is most widely validated for the population that uses the tool, say which one we use, and mention the alternatives where it matters (for example Mifflin-St Jeor vs. Harris-Benedict for BMR).
How calculators are tested
The core formulas of our calculators live in shared, tested code. Automated unit tests check them against reference values from the original sources, for example VDOT race predictions and training paces against Jack Daniels' published tables, treadmill and cycling energy against the ACSM metabolic equations, and calorie estimates against the Compendium's MET values. These tests run whenever the code changes, so a change that would move a result away from the published reference is caught before it goes live. Test coverage is being extended calculator by calculator; not every calculator has its own test suite yet.
We also check worked examples by hand: the example numbers in a methodology section are computed with the same formula the calculator uses, so you can reproduce them yourself.
How content is updated
The site is maintained in version control. The “Updated” date shown on calculators and articles comes from the date the page's content or formula last actually changed in that history. We do not refresh dates to make pages look new. Articles show both the original publication date and, when it is meaningfully later, the date of the last update.
We review calculators when a source publishes a new edition (for example the 2024 update of the Compendium of Physical Activities), when a reader reports a problem, or when we find an error ourselves.
Corrections and feedback
If you think a number, formula or statement on the site is wrong, please tell us via the contact page or by email at jonas@sport-calculator.com. Include the page URL, the inputs you used and, if possible, the source you are comparing against. Confirmed errors are fixed in the calculator and its text, the page's “Updated” date changes with the fix, and where a correction changes results materially we say so on the page.
Advertising, affiliate links and independence
The calculators are free to use. The site is funded by:
- Display advertising served by our ad partner Mediavine. Advertisers have no influence on formulas, results or editorial content, and we do not choose which ads appear.
- Supporter plans (support the site): optional paid plans that unlock extra features such as unlimited file conversions. Free calculator results are never worse because you don't pay.
- Affiliate links on some pages, for example bike parts suggested by the chain length calculator or product roundups on the blog. If you buy through such a link we may earn a small commission at no extra cost to you. Affiliate relationships never change a calculator's result.
Nobody can pay to change a formula, a result or a ranking in our content. If we ever publish sponsored content, it will be clearly labelled as sponsored.
Use of AI tools
We use AI tools to help draft text, translate pages and write code. AI output is treated as a first draft: every formula is taken from its published source, every number on a page is produced by the calculator's own tested code or checked against the source, and the page is reviewed by Jonas before it is published. AI tools are not used to invent sources, experiences, credentials or reviewers.
Limits of calculators
Calculators give estimates for typical people. Equations such as BMR, maximal heart rate or calorie burn have known error ranges, and individual results can differ by 10–20% or more. The information on this site is for education and training planning, not medical advice. If you have a health condition, are pregnant, or are planning a large change to diet or training, talk to a doctor or registered dietitian.