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 micrometre?
A micrometre, also called a micron, is a unit of length equal to one millionth of a metre. It is used in microscopy, semiconductor fabrication, and the measurement of fine particles and biological cells.
Real-world uses
Micrometres (microns) are used to measure biological cells, bacteria, semiconductor chip features, and fine particle sizes in air quality monitoring. Paint film thickness, fibre diameters, and precision machining tolerances are also specified in µm.
History
The micrometre was formalized with SI prefix standardization in the 20th century. The term "micron" was officially revoked by the SI in 1967 in favour of "micrometre," though "micron" persists informally in many industries.
Common mistakes
Using the symbol "u" instead of the correct "µ" (Greek mu). Also, confusing micrometres with nanometres—a human hair is about 70 µm wide, not 70 nm.
When is this conversion used?
Converting between inch and micrometre 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. Screen sizes, paper dimensions, and clothing measurements often require converting between centimetres and inches, especially when shopping internationally.
Worked examples
1 inch = 25,400 micrometre
1 micrometre = 0.000001 metre
How to convert inch to micrometre
To convert inch to micrometre, multiply the value by 25,400.
To convert micrometre back to inch, multiply by 0.00003937.
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 micrometre
| inch | micrometre |
|---|---|
| 0.1 | 2,540 |
| 0.5 | 12,700 |
| 1 | 25,400 |
| 2 | 50,800 |
| 5 | 127,000 |
| 10 | 254,000 |
| 25 | 635,000 |
| 50 | 1,270,000 |
| 100 | 2,540,000 |
| 250 | 6,350,000 |
| 500 | 12,700,000 |
| 1,000 | 25,400,000 |
Common values
| inch | micrometre | |
|---|---|---|
| Height of a door | 82.67716535 inch | 2,100,000 micrometre |
| Basketball court length | 1,102.36220472 inch | 28,000,000 micrometre |
| Football field (soccer) | 4,133.85826772 inch | 105,000,000 micrometre |
| Marathon distance | 1,661,220.47244094 inch | 4.219500e+10 micrometre |
| Altitude of a cruising airplane | 420,000 inch | 1.066800e+10 micrometre |