Converting Between Different Measurement Systems
Measurements often need to be converted when instructions, specifications, tools, or products use a different unit system than the one you normally work with. A dimension may be given in millimeters when you need inches, a weight may be listed in kilograms when you need pounds, or a speed may be shown in kilometers per hour when you are accustomed to miles per hour.
A unit converter makes it easier to compare these values without manually looking up conversion factors and performing separate calculations.
Common Reasons to Convert Units
Unit conversions are useful for home projects, automotive work, cooking, travel, science, electronics, computing, and everyday measurements. They can also help when comparing specifications for products made or sold in different countries.
For example, you might need to convert:
millimeters or centimeters to inches
square meters to square feet
liters to gallons
kilograms to pounds
kilometers per hour to miles per hour
kilopascals or bar to PSI
kilowatts to horsepower
Celsius to Fahrenheit
hours to minutes or seconds
gigabytes to megabytes or binary storage units
Linear, Square, and Cubic Units Are Different
Length, area, and volume measure different things and therefore use different conversion factors. Length measures a single dimension, while area measures a two-dimensional surface and volume measures three-dimensional space.
For example, converting 1 foot to 12 inches does not mean that 1 square foot equals 12 square inches. A square foot contains 144 square inches because both dimensions must be converted. Likewise, cubic measurements require converting all three dimensions.
Choosing the correct conversion category is therefore just as important as choosing the correct units.
Conversion Precision
Converted measurements sometimes produce long decimal values because two measurement systems do not always divide evenly into one another. How much precision you need depends on what the measurement will be used for. Everyday estimates may only require a few decimal places, while machining, engineering, scientific work, or other precision applications may require greater accuracy.
When working from plans or specifications, avoid rounding a converted measurement more than necessary until you reach the final value you intend to use.