Inches (in)
The inch is a unit of length in the imperial and US customary systems equal to exactly 2.54 centimeters.
Convert inches to any length unit
1 inch = 0.0254 meters
Quick facts
- Unit
- Inch (plural: inches)
- Symbol
- in
- Measures
- Length / Distance
- System
- Imperial & US customary
- Equals
- 0.0254 meters
- Definition
- Exactly 2.54 centimeters (1/12 of a foot), by the 1959 international agreement.
1 inch in other units
| Meters | 0.0254 m |
| Centimeters | 2.54 cm |
| Feet | 0.08333333333 ft |
| Kilometers | 0.0000254 km |
| Miles | 0.000015782828 mi |
| Millimeters | 25.4 mm |
| Yards | 0.02777777778 yd |
| Micrometers | 25,400 µm |
What is an inch?
The inch is a unit of length in the imperial and US customary systems equal to exactly 2.54 centimeters. Twelve inches make a foot and 36 inches make a yard. Its symbol is "in" or the double prime (″), as in 6″.
An inch is roughly the width of an adult thumb at the knuckle, which is where the unit comes from: in many languages the word for inch is the same as the word for thumb.
Where the inch sits among length units
The inch is number 46 of 231 on our scale of length units, ordered from smallest to largest.
What inches are used for
- Screen sizes of TVs, monitors and phones (measured diagonally)
- Height of people in the US and UK (5 feet 10 inches)
- Construction, lumber and plumbing in the US
- Wheel and tire sizes worldwide (a 17-inch wheel)
- Rainfall and snowfall in US weather reports
Inches in real life
- A US quarter is just under 1 inch (0.955 in) across
- A standard sheet of US letter paper is 8.5 × 11 inches
- A typical smartphone screen is about 6 inches diagonally
- A standard paperclip is about 1.3 inches long
- A 2×4 board actually measures 1.5 × 3.5 inches
One inch is about the length of a US quarter (diameter), or about 4.2 grains of rice laid end to end, or about 77% of the length of a paperclip, or about 51 grains of sand laid end to end.
History of the inch
The inch was defined in 14th-century England as the length of three barleycorns laid end to end. Its size varied slightly between countries until 1959, when the United States, the United Kingdom and other Commonwealth countries agreed to define it as exactly 25.4 millimeters.
Top inch conversions
Common amounts of inches
- 0.1 in
- 0.2 in
- 0.3 in
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- 1 in
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Convert inches to all 230 other units
Metric (SI)
- in to m
- in to cm
- in to km
- in to mm
- in to µm
- in to nm
- in to dm
- in to pm
- in to fm
- in to dam
- in to hm
- in to Gm
- in to Mm
Imperial & US customary
- in to ft
- in to mi
- in to yd
- in to ftm
- in to fur
- in to hh
- in to th
- in to ch
- in to lea
- in to rd
- in to cubit
- in to barleycorn
- in to li
- in to span
- in to line
- in to ell
- in to palm
- in to Ramsden's chain
- in to finger
- in to nail
- in to shaftment
US survey
Nautical
Astronomical
- in to ly
- in to au
- in to pc
- in to kpc
- in to Mpc
- in to R⊕
- in to ls
- in to light-minute
- in to LD
- in to R☉
- in to Gpc
- in to light-day
- in to light-hour
- in to RJ
- in to light-week
- in to Hubble length
- in to siriometer
Scientific & atomic
Ancient
- in to Roman mile
- in to royal cubit
- in to stadion
- in to Biblical cubit
- in to Roman foot
- in to Greek foot
- in to Roman pace
- in to parasang
- in to Egyptian common cubit
- in to Egyptian digit
- in to Egyptian palm
- in to Gallic league
- in to Greek cubit
- in to Greek finger
- in to Roman cubit
- in to Roman digit
- in to Roman inch
- in to Roman palm
- in to Roman stadium
- in to Roman step
- in to handbreadth
- in to Biblical finger
- in to Biblical parasang
- in to Biblical span
- in to Greek palm
- in to Greek span
- in to Sabbath day's journey
- in to Talmudic mil
- in to bema
- in to beru
- in to day's journey
- in to diaulos
- in to dichas
- in to hippikon
- in to iteru
- in to khet
- in to kondylos
- in to kush
- in to nindan
- in to orgyia
- in to plethron
- in to pygme
- in to reed
- in to remen
- in to shu-si
- in to ush
East & Southeast Asian
- in to 里
- in to 尺
- in to 寸
- in to 尺
- in to 里
- in to 間
- in to 寸
- in to wa
- in to 리
- in to 丈
- in to 步
- in to 分
- in to 厘
- in to 分
- in to 치
- in to 町
- in to 자
- in to 丈
- in to khuep
- in to kujirajaku
- in to nio
- in to sen
- in to sok
- in to 引
- in to yot
- in to 厘
- in to 푼
- in to 毫
- in to 忽
- in to kraphiat
- in to 毛
- in to 丝
South Asian & Middle Eastern
- in to gaj
- in to kos
- in to yojana
- in to angul
- in to farsakh
- in to hasta
- in to arsin
- in to barid
- in to danda
- in to dhira
- in to qasaba
European (pre-metric)
- in to Swedish mil
- in to versta
- in to arshin
- in to lieue
- in to ligne
- in to pied du roi
- in to sazhen
- in to toise
- in to Irish mile
- in to Prussian mile
- in to Russian mile
- in to Scottish mile
- in to pouce
- in to vershok
- in to Danish mile
- in to French point
- in to Prussian ell
- in to Prussian foot
- in to Prussian inch
- in to Prussian rod
- in to Rhineland rod
- in to Russian foot
- in to Swiss hour
- in to aln
- in to aune
- in to duim
- in to dyuym
- in to famn
- in to liniya
- in to pyad
- in to Welsh mile
- in to fjardingsvag
- in to tochka
Spanish & Portuguese
- in to Castilian vara
- in to Spanish league
- in to Texas vara
- in to pulgada
- in to Castilian foot
- in to Mexican vara
- in to braca
- in to legua
- in to Portuguese foot
- in to Portuguese vara
- in to palmo
- in to polegada
- in to Spanish pace
- in to linea
- in to linha
- in to punto
Everyday comparisons
- in to American football field
- in to marathon
- in to smoot
- in to Earth circumference
- in to Eiffel Tower height
- in to Olympic pool length
- in to banana
- in to double-decker bus
- in to soccer pitch length
- in to Mount Everest height
- in to blue whale length
- in to credit card length
- in to human hair width
- in to Burj Khalifa height
- in to Earth diameter
- in to Empire State Building height
- in to Statue of Liberty height
- in to human height
- in to giraffe height
- in to grain of rice
- in to paperclip length
- in to pencil length
- in to sheppey
- in to smartphone length
Convert to inches
Frequently asked questions
What is an inch?
The inch is a unit of length in the imperial and US customary systems equal to exactly 2.54 centimeters.
How is the inch defined?
Exactly 2.54 centimeters (1/12 of a foot), by the 1959 international agreement.
How many meters are in an inch?
One inch equals 0.0254 meters.
How many centimeters are in an inch?
One inch equals 2.54 centimeters.
How many feet are in an inch?
One inch equals 0.08333333333 feet.