About ConvertMaster
ConvertMaster is a free, browser-based unit conversion tool. We built it because the existing converters on the web tend to fall into one of two camps: bare calculators with no explanation, or SEO-stuffed walls of text that hide the actual answer. Our goal is a tool that gives you the result instantly and, if you want it, the reasoning behind the number.
Our mission
Make precise unit conversion accessible to anyone with a browser — students checking homework, home cooks scaling recipes, travelers reading speed-limit signs, and engineers double-checking a datasheet. Every page should be useful on its own, even if you've never visited the site before.
Where the numbers come from
Conversion factors on this site are taken from the International System of Units (SI) as published by the Bureau International des Poids et Mesures (BIPM) and the National Institute of Standards and Technology (NIST) Special Publication 811. Where a unit has multiple historical definitions (for example "calorie" or "ton"), we use the definition most commonly applied in the relevant field and state it explicitly on the page.
Every factor stored in the codebase is the exact value, not a truncated approximation. Calculations are performed in IEEE-754 double precision; results are rounded only for display, never internally.
Editorial standards
- Each reference page is written and reviewed by a human, not auto-generated.
- Worked examples use realistic, verifiable numbers.
- When two unit systems disagree (US vs Imperial gallon, mechanical vs metric horsepower), we name both and explain when each is used.
- Errors are corrected promptly. If you spot one, please tell us.
How we keep the lights on
ConvertMaster is supported by display advertising. Ads are served by Google AdSense and labelled as such. We don't accept paid placements inside reference articles, and our conversion factors are not influenced by any advertiser. See our privacy page for what data is collected and how to opt out of personalized advertising.
Contact
Have a correction, a missing unit, or a feature request? Reach us at hello@convertmaster.pro or via the contact page.