What is foot?
A foot is a unit of length in imperial and US customary systems equal to 12 inches. It is commonly used in construction, architecture, body height measurements, and aviation for altitude references.
Real-world uses
Feet are the primary unit for building dimensions, room sizes, and ceiling heights in the United States. Aviation uses feet for altitude worldwide (e.g., cruising at 35,000 ft). Human height in the US and UK is commonly expressed in feet and inches.
History
The foot has been used since ancient civilizations, with varying lengths based on the local king's foot. The modern international foot was defined in 1959 as exactly 0.3048 metres, replacing slightly different US and British survey definitions.
Common mistakes
Using an apostrophe for feet (6') and confusing it with the prime symbol. Also, people often round 1 foot to 30 cm instead of the correct 30.48 cm, leading to cumulative errors in construction.
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.
When is this conversion used?
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 foot = 12 inch
1 inch = 0.0254 metre
How to convert foot to inch
To convert foot to inch, multiply the value by 12.
To convert inch back to foot, multiply by 0.08333333.
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: foot to inch
| foot | inch |
|---|---|
| 0.1 | 1.2 |
| 0.5 | 6 |
| 1 | 12 |
| 2 | 24 |
| 5 | 60 |
| 10 | 120 |
| 25 | 300 |
| 50 | 600 |
| 100 | 1,200 |
| 250 | 3,000 |
| 500 | 6,000 |
| 1,000 | 12,000 |
Common values
| foot | inch | |
|---|---|---|
| Height of a door | 6.88976378 foot | 82.67716535 inch |
| Basketball court length | 91.86351706 foot | 1,102.36220472 inch |
| Football field (soccer) | 344.48818898 foot | 4,133.85826772 inch |
| Marathon distance | 138,435.03937008 foot | 1,661,220.47244094 inch |
| Altitude of a cruising airplane | 35,000 foot | 420,000 inch |