About Convert Calc

Convert Calc is a free unit conversion tool designed to be fast, accurate, and trustworthy. Every conversion factor is sourced from published standards — primarily NIST SP 811, the SI Brochure (BIPM), and IEC 80000 — not crowdsourced or approximated.

Most online converters use cached conversion factors without source attribution. Convert Calc is different: every conversion formula is cited, every rounding decision is traceable, and every page explains when and why you'd use a particular conversion. If you find a discrepancy with our sources, we want to know.

Each converter page includes the conversion formula, a reference table, real-world examples, and answers to common questions. The source standard for each conversion factor is cited directly on the page.

Convert Calc works fast and reliably, anywhere and anytime. Converter data loads upfront with minimal external requests. We use Cloudflare Web Analytics for privacy-respecting usage insights (no cookies, no personal data). JavaScript is required for interactive conversions, but all formulas, tables, examples, and reference information remain visible and accessible.

Want to learn more? Explore how measurement systems work, read our conversion methodology, or start converting.

Who runs Convert Calc

Convert Calc is written and maintained by Marcus Thompson. The site started as a personal project to fix a recurring annoyance: most unit converters online give you a number with no indication of where it came from, how precise it is, or whether it's even right. Convert Calc cites a source for every conversion factor and explains the practical situations where you'd actually need that conversion — cooking, travel, construction, fitness, and day-to-day life.

Every page on the site is reviewed against its cited source (see our methodology for details on how and when), and content is written to answer real questions people search for — not generic, templated descriptions.

Found something wrong, confusing, or missing? Get in touch — corrections and suggestions directly shape what gets fixed or added next.