Unit Converter
Convert between 60+ units across length, weight, temperature, volume, area, speed, time, and data storage.
All calculations run in your browser
Convert between units across length, weight, temperature (with the Celsius / Fahrenheit / Kelvin formulas applied properly, not just a linear scale), volume, area, speed, time, and digital storage. Pick a category, type a value, and every other unit in that category updates at once. Useful for cooking recipes from another country, engineering specs in mixed units, or sanity-checking that nautical-mile field on a form. Math runs in your tab.
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How to Convert Units of Measurement
Unit Converter implements each conversion as a pure JavaScript multiplication or affine transformation against a base unit per category. Length normalizes to meters, weight to kilograms, volume to liters, area to square meters, speed to meters-per-second, time to seconds, and data storage to bits. The conversion factors are hardcoded constants from the SI brochure and NIST handbook, so a meter-to-foot conversion uses 3.28084, not a runtime lookup.
Temperature is the exception — it requires affine (offset) transformations because the zero points of Celsius, Fahrenheit, and Kelvin are different. Celsius to Fahrenheit uses (C × 9/5) + 32; Celsius to Kelvin uses C + 273.15. The tool special-cases temperature math rather than using a single base-unit factor approach.
All math uses standard JavaScript Number arithmetic, which is IEEE 754 double-precision floating point. This gives about 15-17 significant decimal digits of accuracy — sufficient for any practical engineering or cooking conversion. Some conversions like 1 inch = 2.54 cm are exact under the 1959 international yard agreement; others like miles to nautical miles introduce a small rounding error far below practical relevance.
Data storage units have a notorious gotcha: kilobyte, megabyte, gigabyte, and terabyte are ambiguous. Decimal (SI) interpretation defines 1 KB = 1000 bytes; binary (IEC) interpretation defines 1 KiB = 1024 bytes. Hard drive manufacturers use decimal; RAM manufacturers and operating systems often use binary. This tool exposes both decimal (KB/MB/GB/TB) and binary (KiB/MiB/GiB/TiB) units explicitly so you can pick the right interpretation for your context.
Volume conversions hide another trap: a US fluid ounce (29.5735 mL) differs from a UK/Imperial fluid ounce (28.4131 mL) by about 4%, and a US cup (236.588 mL) differs from a metric cup (250 mL) and an Imperial cup (284.131 mL). For recipes, always check whether the source uses US or metric measurements — this tool labels them distinctly.
The 'All conversions' panel computes every target unit in the selected category in a single render pass. Because each conversion is a single multiplication or affine transform, all 60+ unit conversions complete in well under a millisecond — fast enough to run on every keystroke.
Everything is computed locally; no value you enter is logged, transmitted, or persisted. The tool is a pure-function calculator that runs on your machine and only your machine tab.
Common Use Cases
01
International travel
Convert miles to km, Fahrenheit to Celsius, and pounds to kg before driving, hiking, or cooking abroad.
02
Cooking and baking
Convert cups to mL and ounces to grams when following recipes from a different measurement system.
03
Science and engineering
Convert between SI units and imperial for technical reports, lab work, or aerospace specs that mix systems.
04
Data storage planning
Convert between bytes, KB, MB, GB, TB and the binary KiB/MiB/GiB/TiB for IT capacity planning.
Frequently Asked Questions
Length, weight/mass, temperature, volume, area, speed, time, and digital storage — 8 categories covering 60+ individual units. Each category has a base unit (meter, kilogram, etc.) that all conversions route through.
JavaScript IEEE 754 doubles give 15-17 significant digits, well beyond practical needs. Temperature uses exact affine formulas (e.g., (C × 9/5) + 32), and other categories use NIST/SI conversion constants like 1 inch = 2.54 cm exactly.
It exchanges the From and To unit selectors, recomputing the result with the same input value. Useful for quickly checking 'X miles = Y km' followed by 'Y km = X miles' as a sanity check.
Yes — the All Conversions panel computes every other unit in the selected category from your input. Each conversion is a single multiplication, so the full panel updates instantly on every keystroke.
Decimal kilobyte (KB) = 1,000 bytes (SI); binary kibibyte (KiB) = 1,024 bytes (IEC). Storage manufacturers use decimal (a 1 TB hard drive is 10^12 bytes), while operating systems often report binary (Windows shows it as roughly 931 GiB). This tool lists both — KB/MB/GB/TB for decimal and KiB/MiB/GiB/TiB for binary — so you can match your context.
Both US and Imperial (UK) fluid ounces are listed separately, since they differ by about 4%. Always check your recipe's origin — a US recipe's 'fl oz' is 29.5735 mL, a British one is 28.4131 mL.
The category is labeled weight but uses mass units (kg, g, lb, oz). On Earth, mass and weight are interchangeable for everyday use; for physics problems involving force, multiply by g (9.80665 m/s^2) to get newtons.
Currency conversion requires live exchange rates that change minute-by-minute. Hardcoding rates would be misleading. Use a dedicated FX tool with a live data feed for currency math.
Yes. The input accepts JavaScript number formats including scientific notation like 1.5e3 (= 1500) or 2.5e-6 (= 0.0000025). The result is formatted with up to 8 significant figures by default.
No. All conversion math runs in pure functions in your browser. The values you enter are not logged, not analytics-tracked, and not persisted across page reloads.
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