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How to use the unit converter, and units worth knowing
Foreign recipes, imported specifications, property listings, bathroom scales — an unfamiliar unit makes the number meaningless. This converter handles length, weight, area, volume, temperature and speed in one place.
How to use it
Pick a category, enter a value and a unit, and the equivalents appear at once. Everything recalculates as you type, which makes it easy to move back and forth until the scale feels intuitive.
Traditional Japanese units you will still meet
The Measurement Act restricts these in trade and certification, but several survive by custom. One tsubo is about 3.306 square metres (the area of two tatami mats); one jo (tatami) is about 1.653 square metres, though sizes differ regionally between Kyoma, Chukyoma and Edoma. One sun is about 3.03 cm, one shaku about 30.3 cm, one to is 18.039 L and one go is 180.39 mL. Property adverts quoting tsubo, and sake sold by the go, are both remnants of this system.
Imperial and US customary
One inch is exactly 2.54 cm by definition; a foot is 30.48 cm, a yard 0.9144 m and a mile 1.609 km. For weight, a pound is 453.6 g and an ounce 28.35 g — handy for foreign scales and cabin-baggage limits (often 7 kg, about 15.4 lb).
Temperature shifts as well as scales
Temperature behaves differently from every other unit here, because the zero points differ. Fahrenheit = Celsius × 9/5 + 32, so you multiply and then offset. 0°C is 32°F, 100°C is 212°F, and −40°C equals −40°F — the single point where the two scales meet. Body temperature at 37°C is 98.6°F.
Calories and joules
The kcal on a nutrition label and the joule used in physics are related by 1 kcal = 4.184 kJ. Packaging outside Japan usually leads with kJ, so 2,000 kcal appears as about 8,370 kJ. For dietary calculations, see the calorie calculator.
Watch the rounding
Most conversions do not divide evenly, so displayed values are rounded. Where precision matters — engineering drawings, dosing, trade — check the unrounded value and the significant figures. Errors compound quickly when conversions are chained.
Frequently asked questions
Which units are supported?+
Are the inch and foot factors accurate?+
How is temperature converted?+
Temperature is not proportional, so a dedicated formula is used.
Is my input stored?+
How is tsubo (a Japanese area unit) converted?+
Tatami is not included because its size varies by region.
・Length: 1 inch = 25.4 mm (definition) / 1 ft = 0.3048 m / 1 yd = 0.9144 m / 1 mile = 1609.344 m
・Weight: 1 lb = 0.45359237 kg (definition) / 1 oz = 1/16 lb
・Temperature: F = C × 9/5 + 32 / K = C + 273.15
・Area: 1 tsubo = 400/121 m² / 1 acre = 4046.8564224 m² / 1 ha = 10000 m²
・Bureau International des Poids et Mesures (BIPM). The International System of Units (SI)
・International Yard and Pound Agreement (1959): fixed 1 yard = 0.9144 m and 1 pound = 0.45359237 kg by definition
・Measurement Act and Order for Enforcement of the Measurement Act (Japan): prescribe the legal units for trade and certification
This site does not represent any official body and does not guarantee the accuracy or completeness of the conversions. For trade or metrology where accuracy matters, please rely on certified measuring instruments and official references.