UnitFlip is a free unit converter covering 1,698 units across 74 measurement categories, plus everyday tools for cooking, height, clothing and paper sizes and a set of 12 written guides on how measurement units actually work.
Why this site exists
Most conversion sites answer the arithmetic and stop there. That is usually fine, and occasionally it is not: a gallon means two different volumes, a "cup" means four, an ounce can be a weight or a volume, and a terabyte drive is not the size your computer says it is. Those are the cases where a bare number is not enough, and where a converter that hands you one without comment is quietly unhelpful.
So the aim here is a converter that is fast and correct for the routine cases, and that explains itself for the cases where the units disagree with each other. That is what the guides are for, and why the main conversion pages carry worked formulas and rounding notes rather than just a result.
Who runs it
UnitFlip is owned and operated by NARUON, an independent software company, and is built and maintained by its small team, published under the editorial name UnitFlip Editorial Team. We do not put individual bylines on pages, and we do not claim credentials we have not published — what we do instead is cite the standard behind every number, so you can check the source rather than take our word for it. Every guide and every core conversion page lists the documents it draws on and the date its content was last reviewed.
The people who maintain the unit data read the inbox themselves: you can reach the team directly at ktgtiger@gmail.com or through the contact page.
Where the numbers come from
Conversion factors come from published definitions, not from other converters. Where a unit has an exact legal or standards-body definition, that exact value is stored — the inch as exactly 0.0254 m, the pound as exactly 0.45359237 kg, the US gallon as exactly 231 cubic inches. Where a unit is genuinely approximate or context-dependent, it is labelled as such rather than given false precision.
The reference documents are listed on the sources page, each with the date we last checked the link and what we use it for. The methodology page covers how the calculation actually works, including the non-linear cases.
How the content is written and reviewed
- Unit data is entered against a published definition and covered by an automated test suite that checks known reference values, round-trip stability, and edge cases before anything is published.
- Guides are written by hand for a specific reader question, cite their sources, and carry publication and update dates. None of them is generated from a template.
- Core conversion pages — 46 of them — carry hand-written content specific to that pair: where the conversion is used, the mistakes people make with those two units, the precision that is appropriate, and a reference table of values people actually look up.
- Corrections are made against the published standard, get a regression test so the error cannot return, and update the review date on the affected pages.
A deliberate limit on how many pages exist
With 1,698 units, the number of possible unit pairings runs into the tens of thousands. We do not generate a page for each one, because a page that exists only to match a search phrase is of no use to a reader. Conversions between any two units in a category are available in that category's converter; separate pages exist only where the conversion is one people genuinely look up, and only the ones with hand-written content of their own are submitted for indexing.
Privacy
Every conversion runs in your browser. The values you type are never sent to a server, never logged, and never associated with an account — there are no accounts. Saved and recent conversions are stored locally on your device and can be cleared at any time. See the privacy policy for the full detail, including what analytics and advertising do collect.
Corrections and contact
If a result looks wrong, we want to hear about it — accuracy reports are the first thing we deal with. The contact page explains what to include so we can verify quickly.