Unit Converter
Convert between US and metric units in four categories — length, weight, volume and temperature. Every conversion shows its steps through the base unit, using exact legal factors (an inch is exactly 2.54 cm).
How conversions work
Length, weight and volume convert through a base unit (meter, kilogram, liter): multiply into the base, divide out to the target. The factors are exact by definition — since 1959, 1 in = 2.54 cm and 1 lb = 453.59237 g exactly.
Temperature is different: the scales have shifted zero points, so it's a formula, not a factor — °F = °C × 9⁄5 + 32, and Kelvin is Celsius plus 273.15. That's why 0°C is 32°F, not 0°F.
Worked examples
Example 1: feet to meters
A 12 ft ceiling in meters.
- A foot is exactly 0.3048 m by definition.1 ft = 0.3048 m
- Multiply.12 × 0.3048 = 3.6576
3.66 meters.
Example 2: pounds to kilograms
A 150 lb person in kg.
- A pound is exactly 0.45359237 kg by definition.1 lb = 0.45359237 kg
- Multiply.150 × 0.45359237 = 68.04
68.0 kg.
Example 3: oven temperature
A recipe says 180°C — what's that in Fahrenheit?
- Multiply by 9/5.180 × 1.8 = 324
- Add 32.324 + 32 = 356°F
356°F — set the oven to 350°F, the nearest standard mark.
FAQ
Are the conversion factors exact?+
For length, weight and US liquid volume — yes, they're exact by international definition (1 in = 2.54 cm, 1 lb = 453.59237 g, 1 gal = 231 in³). Rounding only enters in the displayed 6 decimal places.
Why is a US gallon different from a UK gallon?+
The US kept the old wine gallon (3.785 L); the UK redefined the imperial gallon as 4.546 L in 1824. This converter uses US liquid measures — cups, pints, quarts and gallons are all the US versions.
Is a fluid ounce the same as an ounce?+
No — a fluid ounce measures volume (≈29.6 mL), an ounce measures weight (≈28.3 g). They coincide only for water-like liquids, which is where the name came from.
Quick mental rules?+
Miles→km: multiply by 1.6. Kg→lb: double and add 10%. Meters→feet: triple and add 10%. °C→°F: double and add 30 (fine for weather). Each is within a few percent.
Will there be more categories?+
Yes — speed, area and cooking-specific conversions are planned, plus dedicated pages for the big single pairs like kg→lbs (the programmatic X-to-Y series from our keyword map).
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