About House of Units
A home for every unit — built to be fast, plain, and honest about the details most converters skip.
What this is
House of Units is a free unit converter covering everyday categories — length, weight, temperature, volume, time, area, angle, data storage, fuel economy, and Roman numerals — with more on the way. No sign-up, no account, no clutter: pick a category, type a number, get an answer.
What's different here is the reference material sitting alongside each converter. Most conversion tools give you a number and stop. This site tries to also answer the question that number usually raises next — why a UK gallon isn't the same as a US gallon, why "L/100km" and "MPG" need different math instead of a simple scale factor, why there's no Roman numeral for zero. Real explanations, with real sources, not filler text built to pad out a page.
Why it's built this way
A lot of unit converters online are either bare-bones calculators with no context, or content-stuffed pages where the actual tool is buried under paragraphs written to satisfy search engines rather than the person reading them. This site is an attempt to sit in between: a converter that actually works well first, with genuinely useful explanation earned on its own merits — the kind of detail you'd want if you were trying to understand a conversion, not just copy a number.
That also means being upfront about the boring-but-important stuff: how results get rounded, why floating-point arithmetic occasionally produces a number that looks slightly off, and where a conversion factor is exact versus where it's a practical approximation. You can read the details on the How We Round & Format Numbers page.
What's next
More everyday categories are still being added. Further out, there's a section planned specifically for historical and ancient units — Roman miles, medieval measures, and similar — for anyone who runs into one of these in an old document, novel, or historical record and wants to know what it actually means in modern terms. A multilingual version, starting with Danish, is planned after that.
Who's behind it
House of Units is an independently built and maintained project, not a large company. If you spot something wrong — an incorrect conversion factor, a typo, a broken link — the Contact page is the fastest way to reach me.