Unit conversion appears in shopping, travel, engineering and everyday instructions. Always keep the unit next to its number to avoid a misleading result.
Kilograms and grams
One kilogram equals exactly 1,000 grams. An item weighing 2.5 kilograms therefore weighs 2,500 grams. A metric tonne contains 1,000 kilograms.
Miles and kilometers
One international mile is exactly 1.609344 kilometers, so five miles equals 8.04672 kilometers. A nautical mile is different: it equals 1.852 kilometers.
Liters and milliliters
One liter equals 1,000 milliliters. Be careful with gallons: the US liquid gallon and imperial gallon are not the same unit.
Temperature
Temperature conversions require an offset as well as a factor. To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. For example, 100°C equals 212°F.
Good practice
- Choose source and target units explicitly.
- Check decimal separators.
- Keep enough precision for the task.
- Distinguish exact conversion factors from rounded approximations.