Unit Converter: Length, Temperature, Time & More

1 Star 2

Convert length, mass, volume, time, area, speed, digital storage, pressure and temperature without guessing what an abbreviation means. Choose a value and two compatible units, then get a result based on a reviewed conversion registry. Ambiguous systems and calendar durations are labelled instead of silently guessed.

How to use the converter

Enter a number, choose a measurement type, and select the units to convert from and to. Category shortcuts and common conversions make frequent choices faster, while the filter boxes narrow longer unit lists. Press Convert to calculate the result and update the readable fragment after the #. Copy share link copies that completed conversion without changing the URL again. Fragments do not create separate indexable pages.

A decimal comma entered in the form can be normalized to a decimal point. Shared links always use the same dot-based format so the same state has one spelling. Invalid numbers, unknown units, mixed dimensions and duplicate state values are rejected rather than guessed.

Use Swap when you want the reciprocal direction instead of reselecting both units. Copy result includes any calendar alternatives shown beneath the primary answer. The base page canonical and sitemap entry stay unchanged.

Time, months and years

Nanoseconds, microseconds, milliseconds, seconds, minutes, hours, days and weeks have fixed scale factors. Calendar months and years do not. A month can contain 28, 29, 30 or 31 days, while a Gregorian calendar year contains 365 or 366 days.

When a conversion includes months or years, the main result uses the Gregorian averages of 30.436875 days per month and 365.2425 days per year. Separate results show each applicable calendar length, so the average is never presented as the only possible answer.

Area, speed, storage and pressure

Area includes square metric units, square inch, square foot, square yard, the international acre, hectare and international square mile. Speed includes meters per second, kilometers per hour, miles per hour, feet per second and knots.

Digital storage keeps decimal and binary prefixes visibly separate. KB, MB, GB and TB use powers of 1000; KiB, MiB, GiB and TiB use powers of 1024. Bits and bytes are distinct, with exactly eight bits in one byte.

Pressure includes pascals, kilopascals, megapascals, bar, millibar, standard atmosphere, pounds per square inch and torr. These are pressure units, not similarly named mass units.

Temperature and absolute zero

Temperature includes degrees Celsius, degrees Fahrenheit and kelvins. These scales cannot be converted with one multiplier alone because their zero points differ. The calculator therefore applies the exact scale and offset for each unit: 0 °C equals 32 °F and 273.15 K, while −40 °C equals −40 °F.

Kelvin values cannot be negative. Inputs below absolute zero—less than −273.15 °C, −459.67 °F or 0 K—are rejected instead of returning a physically impossible absolute temperature.

Choose the right measurement system

A US liquid gallon is 3.785411784 liters, while an Imperial gallon is 4.54609 liters. Their quarts, pints and fluid ounces differ too. The unit menus therefore say US or Imperial every time. A bare gallon, pint, quart, cup or fluid ounce is not accepted as a share-link unit.

An ounce without the word fluid is an avoirdupois unit of mass. One avoirdupois pound is exactly 16 ounces. A US fluid ounce and an Imperial fluid ounce are units of volume, so neither can be converted to a mass ounce without extra information such as a material density.

Tonne means the metric unit of 1000 kilograms. The separate US short ton is 2000 pounds, and the Imperial long ton is 2240 pounds. Stone remains available as exactly 14 pounds. These names stay visible in results and shared links.

Length from micrometers to parsecs

Metric length options follow SI decimal prefixes. The micrometer is displayed as µm with the MICRO SIGN, while the form can also recognize the Greek mu character or plain um as input aliases. Shared links use the ASCII word micrometers, which avoids two visually similar Unicode spellings.

The inch, foot, yard and mile use the international definitions. A hand is four inches and is mainly used for horse height. The astronomical unit is exactly 149,597,870,700 meters. A light-year is a distance, not a time, and the parsec is defined from the astronomical unit and pi; its displayed decimal is necessarily rounded.

Precision and rounding

The calculator uses exact decimal rational arithmetic and reviewed scale-and-offset definitions rather than displaying binary floating-point noise. It works with extra internal precision, then shows at most 12 significant digits by default, removes meaningless trailing zeros and turns negative zero into zero. Halfway cases use round-half-to-even.

Exact conversion factors do not make an estimate more accurate. If you measured a board only to the nearest centimeter, a converted inch value with many decimal places would imply precision you did not measure. Keep enough digits for the task, and follow the rules or tolerances that apply to trade, engineering, medicine, laboratory work or safety-critical decisions.

Accessibility, privacy and limits

The converter uses visible labels, native controls, a keyboard-operable swap button, a named output and text errors. Result updates are announced politely without moving focus on every keystroke. The layout is designed to reflow on a narrow screen and at high zoom.

Conversions run locally after the initial server-rendered example. The tool requires no account and does not store values in cookies or local storage. Analytics, when enabled with consent, may record a coarse event and allowlisted unit IDs, but not the entered value, copied result or full fragment. Clipboard access happens only when you press Copy.

This general-purpose calculator is not a certified measuring instrument and does not replace field-specific guidance. Check the source definition, required tolerance and local rules before relying on a conversion for regulated trade or a high-consequence decision.

Measurement sources

The registry follows the BIPM SI Brochure for SI units and prefixes, NIST conversion tables for customary units, NIST time and area guidance, NIST temperature definitions, NIST’s IEC binary-prefix reference, the US Naval Observatory Gregorian calendar rules, and IAU resolutions for astronomical definitions.