Unit Converter: Practical Guide

Convert common length, weight, temperature, area and volume measurements using fixed conversion factors. Switch categories, reverse units and compare metric and US units.

What can you convert?

Use the category selector to choose Length, Weight, Temperature, Area, or Volume. Then choose a source unit, destination unit and numeric quantity. The result updates instantly. The tool includes common metric and imperial/US units, but it does not cover every specialized unit or compound quantity such as speed, density or fuel economy.

How linear unit conversion works

For length, weight, area and volume, the engine stores a known factor that converts a unit into a shared base unit. It converts the original quantity into that base and divides by the target unit’s factor:

Converted value = input × source factor ÷ destination factor

For example, a kilometer contains 1,000 meters, and a mile contains exactly 1,609.344 meters. Therefore 1 kilometer ≈ 0.621371 miles.

Common length and weight examples

• 5 km to miles: approximately 3.106856 miles.
• 1 inch to centimeters: exactly 2.54 cm.
• 1 foot to meters: exactly 0.3048 m.
• 1 kilogram to pounds: approximately 2.204623 lb.
• 1 pound to kilograms: exactly 0.45359237 kg.

Display rounding can differ from the internal factor precision. Use enough decimal places for scientific or engineering work.

Temperature conversions need an offset

Temperature scales do not simply multiply by a constant. For Celsius to Fahrenheit, use °F = (°C × 9/5) + 32. For Fahrenheit to Celsius, use °C = (°F − 32) × 5/9. For Celsius to Kelvin, use K = °C + 273.15. Thus 0°C = 32°F = 273.15 K. Kelvin is an absolute scale; physically meaningful temperatures should not be below 0 K.

Area and volume conversions

Area scales with the square of a length factor, whereas volume scales with the cube. One square foot equals exactly 0.09290304 square meters; one hectare equals 10,000 square meters. For liquid volume, the engine labels US gallons and US fluid ounces explicitly. A US gallon is 3.785411784 liters, which is not equal to an imperial gallon.

Using a converter accurately

Make sure source and destination units describe the same physical dimension. Do not use length conversion factors to convert area or vice versa. For international purchases and recipes, distinguish US customary volume units from UK imperial units. Results are provided for convenience; high-precision engineering, medical or legal work may require a specialist standard and documented rounding.

Frequently asked questions

The expandable FAQ section above addresses common usage and interpretation questions. Check the calculator inputs, formula and limitations before using results for important decisions.