What this unit converter does
Eight independent conversion dimensions in one tool: length, weight, area, volume, speed, time, data, and energy. Each dimension has its own unit list and exact conversion factors. Pick a dimension at the top, choose the from and to units, type a value, and the result updates in real time. The swap arrow exchanges from and to in place. The comparison panel below shows the input value rendered in every other unit of the same dimension.
Dimensions and units covered
Length (mm, cm, m, km, in, ft, yd, mi) covers everyday measurement, construction, and navigation. Weight (mg, g, kg, t, oz, lb, st) covers grocery scales, gym, shipping, and UK body weight in stones. Area (mm2 to mi2, plus hectare and acre) covers real estate, agriculture, and floor plans. Volume (ml, L, m3, US/UK gallons, cups, pints, quarts) handles cooking, fuel economy, and engineering. Speed (m/s, km/h, mph, knot, ft/s) covers driving, sailing, and aviation. Time (ms to Julian year) handles intervals and timestamps. Data (decimal KB/MB/GB and binary KiB/MiB/GiB) avoids the common storage-marketing confusion. Energy (J, kJ, cal, kcal, Wh, kWh, BTU) covers food calories, electricity bills, and HVAC sizing.
Metric vs imperial - quick guide
Most of the world uses metric (meters, kilograms, liters, Celsius). The US, UK (partially), and a few others retain imperial units. UK uses imperial pints in pubs but metric for fuel, mixed for body weight (stones for personal, kg for sports). Saudi Arabia, UAE, Qatar, and other Gulf states are fully metric for official measures, but US imperial creeps in via American products, recipes, and gym equipment. When converting recipes from US cookbooks, watch for US gallon (3.785 L) vs UK gallon (4.546 L) - 20% larger. Cars sold in the US use mpg (miles per US gallon); UK uses mpg too but with the UK gallon.
Rounding and precision notes
All factors here are exact where the standard defines them (international yard = 0.9144 m exactly, international pound = 0.45359237 kg exactly, US gallon = 3.785411784 L exactly). Time year is the Julian year (365.25 days, used in astronomy) - the average Gregorian year (365.2425 days) is fractionally shorter but the difference rarely matters. Month is approximated as 30.4375 days (year / 12). Display rounding: 4 decimal places for values 1 and above, 8 for sub-1 values, 2 for large values - then trailing zeros are trimmed. For exact engineering work, use the dimension's most precise unit and a downstream calculator.
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