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Convert length, weight and temperature between metric and imperial units — meters to feet, kilograms to pounds, Celsius to Fahrenheit and more — with a swap button for instant reverse conversions. The translator for a world that refuses to agree on measurements.
Most of the world measures in metric: meters, kilograms, Celsius. The United States — plus a stubborn pocket of everyday British usage — runs on inches, pounds and Fahrenheit. Everyone else lives in the collision zone: recipes from American blogs weighed in cups and ounces, luggage limits in kilograms, a height asked for in feet and inches on a form, a weather forecast in a unit you don't think in. Conversion errors in these moments range from funny (a cake with ten times the flour) to famous — NASA lost a $125 million Mars orbiter in 1999 because one team's software output pound-force seconds while another expected newton-seconds.
This converter covers the three categories daily life actually needs. Length: millimeters through miles, including the inches-feet-yards chain. Weight: grams, kilograms, tonnes, ounces, pounds and stone. Temperature: Celsius, Fahrenheit and Kelvin — handled by formula rather than a simple ratio, because temperature scales start at different zeros, which is why it's the category everyone gets wrong by hand.
Length: You're 5 feet 10 inches and a form wants centimeters. Convert 70 inches (5×12 + 10): 177.8 cm.
Weight: Your suitcase reads 154 lb on a US scale and the airline limit is in kilograms. 154 lb = 69.9 kg — better check that limit twice.
Temperature: A recipe says bake at 350°F; your oven is Celsius. 350°F = 176.7°C — call it 175°C, Gas Mark 4. And normal body temperature, 98.6°F, is the 37°C you already knew.
Multiply by 9/5 and add 32. For example, 25°C × 9/5 = 45, + 32 = 77°F. The converter does it instantly, including Kelvin — but for a mental estimate, doubling Celsius and adding 30 gets you close (25°C → ≈80°F).
Exactly 2.54 — it's defined that way internationally, not measured approximately. A foot (12 inches) is therefore exactly 30.48 cm, and a yard exactly 0.9144 m.
Length and weight scales share a true zero, so conversions are simple multiplications. Celsius and Fahrenheit set their zeros at different points (and Kelvin at absolute zero), so converting needs an offset as well as a scale factor — add or subtract 32 as well as multiplying.
Length: millimeters, centimeters, meters, kilometers, inches, feet, yards and miles. Weight: grams, kilograms, tonnes, ounces, pounds and stone. Temperature: Celsius, Fahrenheit and Kelvin.
The conversion factors are the exact international definitions (2.54 cm per inch, 0.45359237 kg per pound), and results are shown rounded sensibly for everyday use. For engineering work, convert here and keep extra decimal places from the equation shown.
Double the kilograms, then add 10% of that doubled figure. 80 kg → 160 → +16 → 176 lb. The exact answer is 176.4 lb — close enough for luggage and gym plates.