How to convert units
Converting units is easier than it looks: most conversions multiply the value by a fixed factor, while temperature has a special offset relationship. This guide explains the difference, how to read the conversion table, and gives a worked example matching Klar’s unit converter.
Conversion by fixed factors
Most categories (length, weight, area and volume) convert by multiplying the value by a fixed factor around a base unit: the metre for length, the kilogram for weight, the litre for volume. For example 1 km = 1000 m, and 1 kg ≈ 2.20462 lb. Both units must belong to the same category: you cannot convert kilograms (weight) into litres (volume).
Temperature is an offset, not a ratio
Temperature scales start from different zero points: Kelvin from absolute zero, Celsius and Fahrenheit from another zero. So the conversion is affine rather than a fixed ratio: 100 °C = 212 °F, 0 °C = 273.15 K, and −40 °C = −40 °F (the point where both scales meet).
A worked example
Using the calculator’s values: 1000 from m to km. The result: 1 km, and the table shows 1000 m = 1,000,000 mm, and so on for every unit in the length category.
Common mistakes
Among the mistakes: confusing the US gallon with the imperial gallon (the calculator uses the US one), trying to convert units from different categories, picking the same unit on both sides (the calculator blocks it with an error), and forgetting that Celsius and Kelvin do not convert by a fixed factor.
Key takeaways
- Most conversions = value × source-unit factor ÷ target-unit factor.
- Temperature converts by an offset: 100 °C = 212 °F.
- Both units must belong to the same category.
- The calculator shows a table of every conversion for the chosen category.
Frequently asked questions
Why can’t I convert pounds to litres?
Pounds measure weight and litres measure volume — they are different categories. Conversion is only possible between units of the same category.
Does the calculator use the US or imperial gallon?
The US gallon (3.785 l). The imperial gallon is larger (4.546 l).