1,698 units across 74 categories — length, weight, temperature, volume, engineering and science. Type what you need in plain language.
Enter a value and units, for example "10 cm to inches".
Every converter is grouped by what it measures, from everyday lengths to specialist engineering and laboratory units.
The conversions people look up most, each with its own page, formula and reference table.
Choose a category or search by unit name, symbol or measurement type — 74 converters covering 1,698 units.
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Real-life sizes and kitchen measurements that don't fit a simple formula — each of these uses a density, a sizing chart, or a national standard, so the tool shows which basis it used.
Beyond unit conversion, for when the numbers aren't units.
The cases where a bare number is not enough — two different gallons, a terabyte that is not a terabyte, and the rounding rules behind every result.
Every conversion factor comes from published standards, not guesswork, and the same data drives both the calculator and the explanations you read. Results are computed on your device — your numbers never leave your browser and nothing is stored on a server.
Converting a measurement means expressing the same quantity in a different unit — 12 inches and 30.48 centimeters are the same length written two ways. Every conversion multiplies by a factor that says how the two units relate, so nothing about the quantity itself changes, only its label.
The metric system scales by tens (millimeter → meter → kilometer), which makes mental math easy. US customary and imperial units carry historical ratios — 12 inches to a foot, 16 ounces to a pound — and although the two families look independent, since 1959 the inch, pound, and their relatives have been defined exactly in metric terms. Read the full comparison →
Some factors are exact by definition: 1 in = 2.54 cm, 1 lb = 0.45359237 kg. Others are inherently approximate — a "cup of flour" depends on how it is packed, and a month has no fixed number of days. UnitFlip marks ingredient- and convention-dependent results so you know which kind you're getting. Why a cup has no fixed weight →
Results are computed in full double precision and displayed to 8 significant figures by default, with trailing zeros trimmed and scientific notation for extreme magnitudes. You can switch any converter to fixed decimal places when you need a specific rounding — see our methodology for details, or the guide on significant figures and rounding.