What is inch?
An inch is a unit of length in imperial and US customary systems equal to 1/12 of a foot. It is widely used for screen sizes, display resolutions, pipe diameters, and small-scale measurements in everyday contexts.
Real-world uses
Inches are used throughout the United States, Canada (partially), and the UK for screen sizes, pipe diameters, lumber dimensions, and screw/bolt specifications. Display sizes for monitors, TVs, and phones are universally quoted in diagonal inches.
History
The inch has ancient origins, traditionally defined as the width of a man's thumb or three barleycorns laid end to end. It was standardized internationally in 1959 as exactly 25.4 mm, reconciling slight differences between British and American definitions.
Common mistakes
Assuming inch fractions are decimal—1/8 inch is 0.125 inches, not 0.18. Also, confusing nominal lumber sizes (a "2x4" is actually 1.5 × 3.5 inches) with actual inch measurements.
What is metre?
The metre is the SI base unit of length. It is used globally in science, engineering, geography, and everyday measurement as the standard reference for distance.
Real-world uses
The metre is the standard unit for everyday measurements worldwide, from room dimensions and furniture sizes to athletic track events like the 100 m sprint. Engineers, architects, and scientists use it as the fundamental length reference in the SI system.
History
Originally defined in 1793 during the French Revolution as one ten-millionth of the distance from the North Pole to the equator along a meridian through Paris. Since 1983, it is defined by the speed of light in vacuum.
Common mistakes
Confusing "meter" (the measuring device) with "metre" (the unit of length) in British English. Also, people sometimes incorrectly assume 1 metre equals exactly 3 feet; it is actually about 3.281 feet.
When is this conversion used?
Converting between inch and metre is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. This conversion is frequently needed in construction, architecture, and real estate where building codes may specify dimensions in one system while materials are sold in another. Screen sizes, paper dimensions, and clothing measurements often require converting between centimetres and inches, especially when shopping internationally.
Worked examples
1 inch = 0.0254 metre
1 metre = 1 metre
How to convert inch to metre
To convert inch to metre, multiply the value by 0.0254.
To convert metre back to inch, multiply by 39.37007874.
Measurement standards
The metre is one of seven SI base units, maintained by the International Bureau of Weights and Measures (BIPM). Since 2019, it is defined by fixing the numerical value of the speed of light in vacuum to exactly 299,792,458 metres per second.
Did you know?
A human hair is roughly 70 micrometres wide, while a single gold atom measures about 0.144 nanometres in diameter — meaning you could line up nearly half a million atoms across the width of one hair.
Quick reference: inch to metre
| inch | metre |
|---|---|
| 0.1 | 0.00254 |
| 0.5 | 0.0127 |
| 1 | 0.0254 |
| 2 | 0.0508 |
| 5 | 0.127 |
| 10 | 0.254 |
| 25 | 0.635 |
| 50 | 1.27 |
| 100 | 2.54 |
| 250 | 6.35 |
| 500 | 12.7 |
| 1,000 | 25.4 |
Common values
| inch | metre | |
|---|---|---|
| Height of a door | 82.67716535 inch | 2.1 metre |
| Basketball court length | 1,102.36220472 inch | 28 metre |
| Football field (soccer) | 4,133.85826772 inch | 105 metre |
| Marathon distance | 1,661,220.47244094 inch | 42,195 metre |
| Altitude of a cruising airplane | 420,000 inch | 10,668 metre |