CodeKitHubWhat Is This Tool?
A unit converter translates a measurement from one unit system to another — kilometers to miles, pounds to kilograms, Fahrenheit to Celsius. The need is constant: recipes from other countries, shipping weights, weather abroad, real-estate areas, sports speeds and imported product specs all arrive in unfamiliar units.
Most conversions are a precise multiplication (1 inch is exactly 25.4 mm by definition). Temperature is the exception — Celsius, Fahrenheit and Kelvin have different zero points, so the formula involves an offset, which this tool applies correctly.
The exact metric definitions of the imperial units come from a specific treaty: the 1959 International Yard and Pound Agreement between the United States, the United Kingdom and Commonwealth countries, whose values are still the legal definitions in force today.
Why Use It?
- Six categories on one page: length, weight, temperature, area, volume, speed.
- Live conversion as you type, plus a full table of all units in the category.
- Exact standard factors (1 lb = 0.45359237 kg by definition, not a rounded 0.45).
- Includes regional units: Chinese jin (斤) and mu (亩), US cups and gallons.
- Free, instant, works offline once loaded.
How to Use
- Pick the category (length, weight, temperature…).
- Choose the unit you're converting from and enter the value.
- Choose the target unit — the result shows instantly.
- Check the table below for the same value in every other unit.
Example
Input
10 kilometers → milesOutput
6.21371192 milesThe table simultaneously shows 10 km as meters, feet, yards and inches — no repeated lookups.
Common Unit Conversions Chart
A quick-reference table for the conversions people look up most, so you don't have to type a value just to check a common one.
- Length: 1 inch = 2.54 cm · 1 foot = 30.48 cm · 1 meter = 3.28084 ft · 1 mile = 1.60934 km · 1 km = 0.62137 mi
- Weight: 1 pound = 0.45359237 kg · 1 kg = 2.20462 lb · 1 ounce = 28.3495 g · 1 stone = 6.35029 kg
- Temperature: 0°C = 32°F = 273.15 K · 20°C = 68°F · 37°C = 98.6°F (body temp) · 100°C = 212°F
- Volume: 1 US gallon = 3.78541 L · 1 liter = 0.264172 US gal · 1 US cup = 236.588 mL (customary cup; the US legal cup used on nutrition labels is 240 mL) · 1 fl oz = 29.5735 mL
- Area: 1 acre = 4046.86 m² · 1 hectare = 2.47105 acres · 1 sq ft = 0.092903 m²
- Speed: 60 mph = 96.5606 km/h · 100 km/h = 62.1371 mph · 1 knot = 1.852 km/h
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
°F = °C × 9/5 + 32. So 20°C = 68°F. Quick mental check: 0°C = 32°F (freezing), 100°C = 212°F (boiling), and −40° is where the two scales meet.
Are the conversion factors exact?
Yes, where definitions exist: the inch (25.4 mm), pound (0.45359237 kg), mile and gallon have been defined exactly in metric terms since 1959. The tool uses those exact factors, so precision is limited only by display rounding.
Why do UK and US gallons differ?
History — the US kept an older wine gallon (3.785 L) while the UK adopted a larger imperial gallon (4.546 L) in 1824. This tool uses US liquid measures for gallon, pint and cup, which is what most online recipes mean.
What are jin (斤) and mu (亩)?
Traditional Chinese units still in daily use: 1 jin = exactly 500 g (used in markets for food), and 1 mu ≈ 666.67 m² (used for land area). They're included because hundreds of millions of people convert them regularly.
Why does my converted value show many decimal places?
The tool shows up to 8 significant decimals so it's usable for technical work. For everyday purposes, just round — 6.2137 miles is "about 6.2 miles".