Unit Converter — US & Metric, Converted Instantly
Convert miles to kilometers, feet and inches to centimeters, pounds to kilograms, Fahrenheit to Celsius, gallons to liters and more. Built for the units Americans use every day — type a value and the answer updates as you type.
Try a common conversion
How It Works
Every conversion uses the official international definitions of each unit — the same factors used by NIST — so a result here matches what you would get from a scale, a tape measure, or a recipe conversion chart.
Pick a category & units
Choose Distance, Length, Weight, Temperature, or Volume, then pick your “from” and “to” units. US imperial units are listed first by default. Use the swap button to reverse the direction instantly.
Type your value
The result updates as you type — no button to press and no page reload. The exact formula and conversion factor are shown under the result so you can check the math yourself.
Read the result
You get the precise result plus a version rounded to two decimals — the way speed limits, luggage weights, and weather reports are normally written.
The math behind it: length and distance convert through meters (1 mile = 1,609.344 m, 1 foot = 0.3048 m, 1 inch = 0.0254 m). Weight converts through kilograms (1 lb = 0.45359237 kg, 1 oz = 28.349523125 g). Volume converts through liters using US measures (1 US gallon = 3.78541 L, 1 US cup = 236.588 ml). Temperature uses °C = (°F − 32) × 5/9. Because everything runs in your browser, no value you enter ever leaves your device.
Popular US to Metric Conversions
The conversions Americans look up most — verified against the factors above. Tap any preset above the table in the converter to run one live.
| Conversion | Factor | Example | Result |
|---|---|---|---|
| Miles → Kilometers | × 1.60934 | 10 miles | 16.09 km |
| Pounds → Kilograms | × 0.453592 | 180 lb | 81.65 kg |
| Fahrenheit → Celsius | (°F − 32) × 5/9 | 68°F | 20°C |
| US Gallons → Liters | × 3.78541 | 5 gallons | 18.93 liters |
| Feet → Centimeters | × 30.48 | 6 ft | 182.88 cm |
| Inches → Centimeters | × 2.54 | 12 in | 30.48 cm |
| Ounces → Grams | × 28.3495 | 16 oz | 453.59 g |
| US Cups → Milliliters | × 236.588 | 2 cups | 473.18 ml |
| Kilometers → Miles | × 0.621371 | 5 km | 3.11 miles |
| Kilograms → Pounds | × 2.20462 | 70 kg | 154.32 lb |
Frequently Asked Questions
Quick answers to the unit questions people in the US ask most.
How do I convert miles to kilometers?
Multiply the miles by 1.60934. For example, 10 miles × 1.60934 = 16.09 km (rounded to two decimals). To convert back from kilometers to miles, divide by 1.60934 — or just use the swap button above.
How many kilograms is 180 pounds?
180 pounds is 81.65 kg. Multiply pounds by 0.453592 to get kilograms: 180 × 0.453592 = 81.65 kg (rounded to two decimals). This is the conversion used for luggage limits and body weight outside the US.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9. For example, 68°F: (68 − 32) × 5/9 = 20°C exactly — a mild spring day. To go the other way, multiply Celsius by 9/5 and add 32. Handy anchors: 32°F = 0°C (freezing) and 98.6°F = 37°C (body temperature).
How many liters are in a US gallon?
One US gallon is 3.78541 liters, so 5 gallons = 18.93 liters (rounded to two decimals). Watch out: a US gallon is not the same as a UK imperial gallon, which is larger at 4.54609 liters. This converter always uses US gallons.
How many centimeters are in a foot?
One foot is exactly 30.48 centimeters, so a person who is 6 ft tall is 182.88 cm. One inch is exactly 2.54 cm — useful for screen sizes, which are sold in inches almost everywhere.
Is this unit converter free, and is my data saved?
Yes — it is completely free, with no sign-up and no limits. Conversions run instantly in your browser, and nothing you enter is saved, stored, or sent to a server.
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