Unit Converter
Select the category (length, weight, volume, or temperature), enter a value, and convert between metric and imperial units instantly.
Conversion uses standard conversion factors: 1 inch = 2.54 cm, 1 lb = 0.453592 kg, 1 gallon = 3.78541 liters, etc.
Conversion Factors Used
Length: - 1 inch = 2.54 cm (exact) - 1 foot = 30.48 cm (exact) - 1 yard = 0.9144 m (exact) - 1 mile = 1.60934 km - 1 millimetre = 0.03937 inch - 1 centimetre = 0.3937 inch - 1 metre = 3.28084 feet - 1 kilometre = 0.621371 miles
Weight: - 1 pound = 0.453592 kg - 1 ounce = 28.3495 g - 1 kilogram = 2.20462 lb - 1 stone = 14 lb = 6.35029 kg
Volume: - 1 gallon = 3.78541 litres (US liquid gallon) - 1 quart = 0.946353 litres - 1 pint = 0.473176 litres - 1 cup = 236.588 ml - 1 litre = 0.264172 gallons
Temperature (exact formulas): - °F to °C: (°F - 32) × 5⁄9 - °C to °F: (°C × 9⁄5) + 32 - Kelvin = Celsius + 273.15
Worked Examples
Example 1: Convert 10 inches to centimetres: → 10 × 2.54 = 25.4 cm
Example 2: Convert 5 pounds to kilograms: → 5 × 0.453592 = 2.26796 kg ≈ 2.27 kg
Example 3: Convert 3 gallons to litres: → 3 × 3.78541 = 11.35623 litres ≈ 11.36 litres
Example 4: Convert 68 °F to Celsius: → (68 - 32) × 5⁄9 = 36 × 5⁄9 = 20 °C
Important Notes
1. Temperature conversions use exact formulas (not simple multiplication factors). 2. Weight and volume conversions use rounded factors for display precision (typically 5-6 decimal places). 3. For scientific or trading purposes, always use official conversion standards. 4. The US gallon (3.785 L) is different from the UK imperial gallon (4.546 L) - this calculator uses US gallons.
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Open calculator →Frequently Asked Questions
Why do my conversions show more decimal places than expected?
Conversion factors have inherent precision. For everyday use, rounding to 2-3 decimal places is usually sufficient. For engineering or scientific work, use the full precision shown.
Is the temperature conversion exact?
Yes. The Fahrenheit-to-Celsius and Celsius-to-Fahrenheit formulas are exact mathematical conversions. The Kelvin scale is defined as Celsius + 273.15 exactly.
Should I use US or imperial gallons?
This calculator uses US gallons (3.785 litres). If you need UK imperial gallons (4.546 litres), adjust the result accordingly or specify which you are using.
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