Curio

Unit Converter

Fast, client-side conversion across metric, imperial and customary units.

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Units of measurement are human agreements, and the awkward coexistence of metric, imperial, and US customary systems is a historical artifact of commerce and manufacturing momentum. While the metric system was established during the French Revolution to replace hundreds of conflicting regional measures with decimal powers, Britain and North America had already established industrial tooling measured in fractions of inches and pounds.

Overhauling machine shops, screw threads, and pipe fittings across an entire continent proved prohibitively expensive. When the United States and Commonwealth nations agreed on international standards in the 1959 International Yard and Pound Agreement, they did not abolish customary units; instead, they redefined customary units in terms of metric constants. An inch is no longer the length of three barleycorns; it is legally defined as exactly 25.4 millimetres. Similarly, the international pound was fixed at exactly 0.45359237 kilograms. Every imperial and customary unit used today is a metric measurement wearing a historical disguise.

Volume measurement carries an even older divergence. In 1824, Britain rationalised its liquid measures by replacing medieval wine, ale, and corn gallons with a single Imperial gallon defined by the weight of water. The United States had declared independence nearly fifty years earlier and retained the 1707 Queen Anne wine gallon of exactly 231 cubic inches. Because of this split, an Imperial pint (568 ml) is roughly twenty percent larger than a US customary pint (473 ml). In recipes and fluid measurements, confusing the two causes noticeable errors.

This converter treats every unit as an exact mathematical ratio against the International System of Units (SI). Temperature scales use explicit offset formulas rather than simple scaling factors, and digital storage explicitly separates decimal gigabytes (10⁹ bytes) from binary gibibytes (2³⁰ bytes). Because all calculations execute directly in JavaScript on your device, conversions resolve instantly and function completely offline without transmitting data across a network.

Controls

Tab / Shift+TabMove focus between category tabs, unit dropdowns, and value inputs.
Number keysType values directly into either field for live two-way conversion.
Up / Down arrowsSelect different units in the dropdown menus.

Questions

Are these unit conversions exact?

Yes. Every conversion factor in this tool is tied directly to international treaty standards rather than rounded approximations. For instance, the inch is defined as exactly 25.4 millimetres and the international pound is exactly 0.45359237 kilograms under the 1959 International Yard and Pound Agreement.

Why do US and Imperial liquid pints differ?

In 1824, the British Imperial Weights and Measures Act standardised the gallon as the volume of 10 pounds of distilled water at 62 °F (4.54609 litres), creating an imperial pint of 568.26 millilitres. The United States preserved the older British Queen Anne wine gallon of 1707 (231 cubic inches or 3.78541 litres), which yields a smaller pint of 473.18 millilitres.

What is the difference between a kilobyte (KB) and a kibibyte (KiB)?

A kilobyte (KB) relies on the decimal SI system where kilo means 1,000 (10³ bytes), standard in storage hardware marketing and network bandwidth. A kibibyte (KiB) is an IEC binary standard meaning 1,024 (2¹⁰ bytes), which matches how operating systems address RAM and file sizes.

Why is there no currency converter included?

Currency values fluctuate minute by minute and require live network requests to financial market endpoints. Curio is built entirely client-side: everything runs in your browser without tracking, cookies, or remote API calls. Adding currency would break that offline privacy guarantee.