Unit Converter for Weight, Length and Temperature
Convert common weight, length and temperature units. Negative weights and lengths and temperatures below absolute zero are rejected.
Quick answer. Convert by multiplying the value by the factor from the starting unit to the base unit, then dividing by the factor from the target unit to the base unit.
How conversion works
Weight converts through kilograms and length converts through meters. Each unit has a fixed multiplier to the base unit.
Temperature uses formulas rather than multipliers. Fahrenheit equals Celsius multiplied by 9 divided by 5, plus 32.
Worked example
1 mile is 1,609.344 meters, which is 1.609344 kilometers.
100 degrees Fahrenheit equals (100 minus 32) multiplied by 5 divided by 9, which is 37.78 degrees Celsius.
Common mistakes
Mixing pounds and kilograms. 1 kilogram is about 2.2046 pounds, not 2.
Entering a negative weight or length. Physical weight and length cannot be negative.
Metric and imperial systems
Most of the world uses the metric system. The United States uses customary units, and the United Kingdom uses imperial units for many everyday measures. Converting between them is common for travel, cooking and building.
The conversion factors used here are exact for the pound, the foot, the inch and the mile. Results are shown to six significant figures.
Worked example with length
Five kilometres divided by 1.609344 gives 3.10686 miles, rounded to six significant figures.
Converting in the other direction, 3.10686 miles multiplied by 1.609344 gives back 5 kilometres.
Temperature is different
Temperature scales have different zero points, so the calculator uses formulas instead of multiplication. Kelvin starts at absolute zero, so it cannot be negative.
Questions
Why is a negative weight rejected?
A physical weight or length cannot be negative. Temperature in Celsius and Fahrenheit can be negative.
Why is Kelvin rejected below zero?
Zero Kelvin is absolute zero. No temperature can be lower.
How many kilograms are in a pound?
One pound is exactly 0.45359237 kilograms.
How do I convert Celsius to Fahrenheit?
Multiply Celsius by 9, divide by 5, then add 32.
Last updated: 2026-10-08. Conversion factors follow standard SI and imperial definitions, for example 1 pound equals 0.45359237 kilograms exactly. Conversion factors checked against published definitions.