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Length Conversion | Millimeter (mm) → Centimeter (cm)

Input Length | mm

Output Length | cm

Length Conversion

Convert between units of length across four systems: metric, imperial, nautical, and traditional surveying units. The range runs from the angstrom, used to measure atoms, up to the kilometer and the mile. Enter a value in one unit and the equivalent appears immediately in the unit you select. Everything is calculated in your browser.

Supported Units

Metric System

Name	Description	Conversions
Angstrom (Å)	The Angstrom (Å) is a unit of length commonly used to measure very small distances, particularly in the fields of physics, chemistry and materials science. It is equal to 1 x 10^-10 meters (0.1 nanometers), making it useful for describing atomic and molecular scales, such as the size of atoms, wavelengths of light, or the spacing between atoms in a crystal. Conversions: 1 Å = 0.1 nm = 1 x 10^-10 meters Common Uses: Atomic and Molecular Measurements Describes the size of atoms and the bond lengths between them. X-ray Crystallography Used to express the resolution of X-ray diffraction patterns. Wavelengths of Light Commonly used to measure the wavelengths of ultraviolet light.	1 Å = 1e-1 nm 1 Å = 1e-4 µm 1 Å = 1e-7 mm 1 Å = 1e-8 cm 1 Å = 1e-9 dm 1 Å = 1e-10 m 1 Å = 1e-13 km 1 Å = 3.937008e-9 in 1 Å = 3.28084e-10 ft 1 Å = 1.093613e-10 yd 1 Å = 6.213712e-14 mi 1 Å = 5.399568e-14 nmi 1 Å = 5.468066e-11 fm 1 Å = 4.97097e-10 Link 1 Å = 4.97097e-12 Chain
Nanometer (nm)	The Nanometer (nm) is a unit of length equal to one billionth of a meter (1 nm = 1 x 10^-9 meters). It is commonly used to measure very small distances, especially in fields like nanotechnology, physics, biology and materials science. Conversions: 1 nm = 1 x 10^-9 meters Common Uses: Wavelengths of Light Used to measure the wavelengths of visible and ultraviolet light (e.g., visible light ranges from about 400 nm to 700 nm). Nanotechnology Describes the scale of nanomaterials and devices, such as carbon nanotubes and semiconductor components. Biology Used to measure the size of molecules and cellular structures.	1 nm = 1e+1 Å 1 nm = 1e-3 µm 1 nm = 1e-6 mm 1 nm = 1e-7 cm 1 nm = 1e-8 dm 1 nm = 1e-9 m 1 nm = 1e-12 km 1 nm = 3.937008e-8 in 1 nm = 3.28084e-9 ft 1 nm = 1.093613e-9 yd 1 nm = 6.213712e-13 mi 1 nm = 5.399568e-13 nmi 1 nm = 5.468066e-10 fm 1 nm = 4.97097e-9 Link 1 nm = 4.97097e-11 Chain
Micrometer (µm)	The Micrometer (µm) is a unit of length equal to one millionth of a meter (1 µm = 10^-6 meters). It is commonly used to measure small objects or distances, particularly in biology, materials science and engineering. Conversions: 1 µm = 10^-6 meters Common Uses: Biology Measures the size of cells, bacteria and microscopic organisms. Materials Science Used to describe the thickness of materials like paper, coatings and films. Engineering Common in precision machining to measure tolerances and the diameter of small components.	1 µm = 1e+4 Å 1 µm = 1e+3 nm 1 µm = 1e-3 mm 1 µm = 1e-4 cm 1 µm = 1e-5 dm 1 µm = 1e-6 m 1 µm = 1e-9 km 1 µm = 3.937008e-5 in 1 µm = 3.28084e-6 ft 1 µm = 1.093613e-6 yd 1 µm = 6.213712e-10 mi 1 µm = 5.399568e-10 nmi 1 µm = 5.468066e-7 fm 1 µm = 4.97097e-6 Link 1 µm = 4.97097e-8 Chain
Millimeter (mm)	The Millimeter (mm) is a unit of length in the metric system, equal to one thousandth of a meter (1 mm = 10^-3 meters). It is commonly used for measuring small objects and dimensions in everyday life, engineering and science. Conversions: 1 mm = 10^-3 meters Common Uses: Everyday Measurements Used to measure small lengths, such as the thickness of a coin, the width of a pencil or the height of small objects. Engineering and Manufacturing Measures precise dimensions in machining, construction and design. Scientific Measurements Used in laboratory measurements and biological studies, like the size of cells or microorganisms.	1 mm = 1e+7 Å 1 mm = 1e+6 nm 1 mm = 1e+3 µm 1 mm = 1e-1 cm 1 mm = 1e-2 dm 1 mm = 1e-3 m 1 mm = 1e-6 km 1 mm = 3.937008e-2 in 1 mm = 3.28084e-3 ft 1 mm = 1.093613e-3 yd 1 mm = 6.213712e-7 mi 1 mm = 5.399568e-7 nmi 1 mm = 5.468066e-4 fm 1 mm = 4.97097e-3 Link 1 mm = 4.97097e-5 Chain
Centimeter (cm)	The Centimeter (cm) is a unit of length in the metric system, equal to one hundredth of a meter (1 cm = 10^-2 meters). It is commonly used for everyday measurements, particularly when measuring objects or distances that are too small for meters but too large for millimeters. Conversions: 1 cm = 10^-2 meters Common Uses: Everyday Measurements Used to measure dimensions of objects like furniture, height of people and length of paper. Construction and Design Common in measuring small-scale dimensions in architecture, engineering and interior design. Science Often used in fields like biology for measuring the size of larger cells or organisms.	1 cm = 1e+8 Å 1 cm = 1e+7 nm 1 cm = 1e+4 µm 1 cm = 1e+1 mm 1 cm = 1e-1 dm 1 cm = 1e-2 m 1 cm = 1e-5 km 1 cm = 3.937008e-1 in 1 cm = 3.28084e-2 ft 1 cm = 1.093613e-2 yd 1 cm = 6.213712e-6 mi 1 cm = 5.399568e-6 nmi 1 cm = 5.468066e-3 fm 1 cm = 4.97097e-2 Link 1 cm = 4.97097e-4 Chain
Decimeter (dm)	The Decimeter (dm) is a unit of length in the metric system, equal to one tenth of a meter (1 dm = 10^-1 meters). It is less commonly used in everyday measurements but is sometimes applied in scientific and technical contexts when a more convenient size than centimeters or meters is needed. Conversions: 1 dm = 10^-1 meters Common Uses: Scientific Measurements Occasionally used in fields like physics and engineering for moderate lengths. Geography and Cartography Can be used for specific applications that require measurements between millimeters and meters. Education Sometimes used in teaching to demonstrate the scale of measurements larger than a centimeter but smaller than a meter.	1 dm = 1e+9 Å 1 dm = 1e+8 nm 1 dm = 1e+5 µm 1 dm = 1e+2 mm 1 dm = 1e+1 cm 1 dm = 1e-1 m 1 dm = 1e-4 km 1 dm = 3.937008e+0 in 1 dm = 3.28084e-1 ft 1 dm = 1.093613e-1 yd 1 dm = 6.213712e-5 mi 1 dm = 5.399568e-5 nmi 1 dm = 5.468066e-2 fm 1 dm = 4.97097e-1 Link 1 dm = 4.97097e-3 Chain
Meter (m)	The Meter (m) is the base unit of length in the International System of Units (SI). It is widely used to measure length or distance in most fields, including science, engineering and everyday life. Conversions: 1 meter (m) = 100 centimeters (cm) = 1,000 millimeters (mm) Common Uses: Everyday Measurements Measures distances, room dimensions, height of individuals and lengths of objects. Scientific and Engineering Applications Standard unit for precise measurements in physics, engineering and construction. Global Standard Used universally for international measurements, from small-scale objects to large distances like the dimensions of buildings or the length of roads.	1 m = 1e+10 Å 1 m = 1e+9 nm 1 m = 1e+6 µm 1 m = 1e+3 mm 1 m = 1e+2 cm 1 m = 1e+1 dm 1 m = 1e-3 km 1 m = 3.937008e+1 in 1 m = 3.28084e+0 ft 1 m = 1.093613e+0 yd 1 m = 6.213712e-4 mi 1 m = 5.399568e-4 nmi 1 m = 5.468066e-1 fm 1 m = 4.97097e+0 Link 1 m = 4.97097e-2 Chain
Kilometer (km)	The Kilometer (km) is a unit of length in the metric system, equal to 1,000 meters (1 km = 1,000 m). It is commonly used to measure longer distances, such as those between cities, along roads or across countries. Conversions: 1 km = 1,000 meters (m) Common Uses: Travel and Transportation Measures distances on roads, highways and between locations (e.g., the distance between cities or landmarks). Geography Used for measuring large-scale distances in maps and geographical studies. Sports Commonly used in events like running, cycling and motorsports (e.g., a 5 km race).	1 km = 1e+13 Å 1 km = 1e+12 nm 1 km = 1e+9 µm 1 km = 1e+6 mm 1 km = 1e+5 cm 1 km = 1e+4 dm 1 km = 1e+3 m 1 km = 3.937008e+4 in 1 km = 3.28084e+3 ft 1 km = 1.093613e+3 yd 1 km = 6.213712e-1 mi 1 km = 5.399568e-1 nmi 1 km = 5.468066e+2 fm 1 km = 4.97097e+3 Link 1 km = 4.97097e+1 Chain

Imperial System

Name	Description	Conversions
Inch (in)	The Inch (in) is a unit of length in the imperial system (also known as the U.S. customary system) commonly used in the United States and some other countries. It is equal to 1/12 of a foot or 2.54 centimeters. Conversions: 1 inch = 2.54 centimeters (cm) 1 inch = 1/12 foot Common Uses: Everyday Measurements Measures small lengths like the width of a screen, dimensions of objects and clothing sizes (e.g., waist measurements). Construction and Engineering Used to measure building materials, tools and hardware. Furniture and Design Common in interior design for specifying dimensions of furniture, windows and doors.	1 in = 2.54e+8 Å 1 in = 2.54e+7 nm 1 in = 2.54e+4 µm 1 in = 2.54e+1 mm 1 in = 2.54e+0 cm 1 in = 2.54e-1 dm 1 in = 2.54e-2 m 1 in = 2.54e-5 km 1 in = 8.333333e-2 ft 1 in = 2.777778e-2 yd 1 in = 1.578283e-5 mi 1 in = 1.37149e-5 nmi 1 in = 1.388889e-2 fm 1 in = 1.262626e-1 Link 1 in = 1.262626e-3 Chain
Foot (ft)	The Foot (ft) is a unit of length in the imperial system (also used in the U.S. customary system). It is equal to 12 inches or 0.3048 meters. Conversions: 1 foot = 12 inches 1 foot = 0.3048 meters (m) Common Uses: Everyday Measurements Used to measure height, room dimensions and distances (e.g., a person's height in feet and inches). Construction and Engineering Common in building and construction for measuring lengths, widths and heights. Design and Manufacturing Used in various industries, including carpentry, textiles and aerospace.	1 ft = 3.048e+9 Å 1 ft = 3.048e+8 nm 1 ft = 3.048e+5 µm 1 ft = 3.048e+2 mm 1 ft = 3.048e+1 cm 1 ft = 3.048e+0 dm 1 ft = 3.048e-1 m 1 ft = 3.048e-4 km 1 ft = 1.2e+1 in 1 ft = 3.333333e-1 yd 1 ft = 1.893939e-4 mi 1 ft = 1.645788e-4 nmi 1 ft = 1.666667e-1 fm 1 ft = 1.515152e+0 Link 1 ft = 1.515152e-2 Chain
Yard (yd)	The Yard (yd) is a unit of length in the imperial system and U.S. customary system, equal to 3 feet or 36 inches. It is commonly used for measuring medium-length distances. Conversions: 1 yard = 3 feet = 36 inches 1 yard = 0.9144 meters (m) Common Uses: Everyday Measurements Used to measure lengths in sports (e.g., yards in football), fabric and clothing. Construction and Engineering Used to measure distances in landscaping, building materials and land areas. Land Measurement Sometimes used in real estate or agriculture to measure plots of land.	1 yd = 9.144e+9 Å 1 yd = 9.144e+8 nm 1 yd = 9.144e+5 µm 1 yd = 9.144e+2 mm 1 yd = 9.144e+1 cm 1 yd = 9.144e+0 dm 1 yd = 9.144e-1 m 1 yd = 9.144e-4 km 1 yd = 3.6e+1 in 1 yd = 3e+0 ft 1 yd = 5.681818e-4 mi 1 yd = 4.937365e-4 nmi 1 yd = 5e-1 fm 1 yd = 4.545455e+0 Link 1 yd = 4.545455e-2 Chain
Mile (mi)	The Mile (mi) is a unit of length in the imperial system and U.S. customary system, commonly used to measure longer distances, especially in travel and geography. It is equal to 1,760 yards or 5,280 feet. Conversions: 1 mile = 1,760 yards = 5,280 feet 1 mile = 1.609344 kilometers (km) Common Uses: Travel and Transportation Measures distances between cities, along roads and in navigation. Geography Used for large-scale distance measurements, such as in mapping and land surveying. Sports Commonly used in long-distance running events (e.g., a 5-mile race).	1 mi = 1.609344e+13 Å 1 mi = 1.609344e+12 nm 1 mi = 1.609344e+9 µm 1 mi = 1.609344e+6 mm 1 mi = 1.609344e+5 cm 1 mi = 1.609344e+4 dm 1 mi = 1.609344e+3 m 1 mi = 1.609344e+0 km 1 mi = 6.336e+4 in 1 mi = 5.28e+3 ft 1 mi = 1.76e+3 yd 1 mi = 8.689762e-1 nmi 1 mi = 8.8e+2 fm 1 mi = 8e+3 Link 1 mi = 8e+1 Chain

Nautical Units

Name	Description	Conversions
Nautical Mile (nmi)	The Nautical Mile (nmi) is a unit of length used primarily in maritime and aviation navigation, based on the circumference of the Earth. It is defined as 1,852 meters or about 1.15078 miles. Conversions: 1 nautical mile = 1,852 meters (m) 1 nautical mile ≈ 1.15078 miles (mi) Common Uses: Maritime and Aviation Navigation Used to measure distances between locations on the Earth's surface, especially at sea or in the air. Mapping Often used in charts and maps for global navigation, as it relates to degrees of latitude. International Standards Used universally in global navigation to ensure consistent distance measurement across different systems and countries.	1 nmi = 1.852e+13 Å 1 nmi = 1.852e+12 nm 1 nmi = 1.852e+9 µm 1 nmi = 1.852e+6 mm 1 nmi = 1.852e+5 cm 1 nmi = 1.852e+4 dm 1 nmi = 1.852e+3 m 1 nmi = 1.852e+0 km 1 nmi = 7.291339e+4 in 1 nmi = 6.076115e+3 ft 1 nmi = 2.025372e+3 yd 1 nmi = 1.150779e+0 mi 1 nmi = 1.012686e+3 fm 1 nmi = 9.206236e+3 Link 1 nmi = 9.206236e+1 Chain
Fathom (fm)	The Fathom (fm) is a unit of length used primarily in maritime contexts to measure depth of water or the height of underwater objects. It is equal to 6 feet or 1.8288 meters. Conversions: 1 nautical fathom = 6 feet (ft) 1 nautical fathom = 1.8288 meters (m) Common Uses: Maritime Navigation Used to measure the depth of water, often found on nautical charts and in sonar measurements. Fishing and Diving Common in underwater activities to measure the depth of bodies of water. Geography and Oceanography Used to describe the depth of oceans, lakes or rivers.	1 fm = 1.8288e+10 Å 1 fm = 1.8288e+9 nm 1 fm = 1.8288e+6 µm 1 fm = 1.8288e+3 mm 1 fm = 1.8288e+2 cm 1 fm = 1.8288e+1 dm 1 fm = 1.8288e+0 m 1 fm = 1.8288e-3 km 1 fm = 7.2e+1 in 1 fm = 6e+0 ft 1 fm = 2e+0 yd 1 fm = 1.136364e-3 mi 1 fm = 9.87473e-4 nmi 1 fm = 9.090909e+0 Link 1 fm = 9.090909e-2 Chain

Traditional Units

Name	Description	Conversions
Link	The Link is a unit of length used in land surveying and is defined as 1/100 of a chain. It is equal to 7.92 inches or 0.201168 meters. Conversions: 1 link = 7.92 inches = 0.201168 meters (m) Common Uses: Surveying and Land Measurement Traditionally used in land surveying, especially for measuring distances in the U.S. and the UK. Historic Applications Often used in combination with the chain (66 feet) to measure land areas for property and construction.	1 Link = 2.01168e+9 Å 1 Link = 2.01168e+8 nm 1 Link = 2.01168e+5 µm 1 Link = 2.01168e+2 mm 1 Link = 2.01168e+1 cm 1 Link = 2.01168e+0 dm 1 Link = 2.01168e-1 m 1 Link = 2.01168e-4 km 1 Link = 7.92e+0 in 1 Link = 6.6e-1 ft 1 Link = 2.2e-1 yd 1 Link = 1.25e-4 mi 1 Link = 1.08622e-4 nmi 1 Link = 1.1e-1 fm 1 Link = 1e-2 Chain
Chain	The Chain is a unit of length traditionally used in land surveying. It is equal to 66 feet or 20.1168 meters. The chain is primarily used for measuring larger distances in land measurement and surveying tasks. Conversions: 1 chain = 66 feet (ft) = 20.1168 meters (m) Common Uses: Surveying Historically, the chain was used to measure distances in land surveys, especially in the U.S. and the UK. Mapping and Property Measurement Often used to describe land plots and to mark boundaries in rural areas.	1 Chain = 2.01168e+11 Å 1 Chain = 2.01168e+10 nm 1 Chain = 2.01168e+7 µm 1 Chain = 2.01168e+4 mm 1 Chain = 2.01168e+3 cm 1 Chain = 2.01168e+2 dm 1 Chain = 2.01168e+1 m 1 Chain = 2.01168e-2 km 1 Chain = 7.92e+2 in 1 Chain = 6.6e+1 ft 1 Chain = 2.2e+1 yd 1 Chain = 1.25e-2 mi 1 Chain = 1.08622e-2 nmi 1 Chain = 1.1e+1 fm 1 Chain = 1e+2 Link

The Four Systems

Metric

Every metric unit is a power of ten away from the meter, which is what makes the system easy to work in: converting is a matter of moving the decimal point rather than remembering a conversion factor. The meter is defined by fixing the speed of light at exactly 299,792,458 meters per second, so it is tied to a constant of nature rather than to a physical object.

Imperial and US customary

Inches, feet, yards, and miles remain in everyday use in the United States and, for some purposes, the United Kingdom. The factors between them are irregular — 12 inches to a foot, 3 feet to a yard, 1,760 yards to a mile — which is precisely why a converter is useful. Since 1959 the inch has been defined as exactly 25.4 millimeters, so imperial and metric values now relate by an exact figure rather than an approximation.

Nautical

The nautical mile is 1,852 meters and corresponds to one minute of arc of latitude, which is what makes it natural for navigation: a degree of latitude is 60 nautical miles anywhere on Earth. The fathom, six feet, is the traditional unit of water depth. Note that a nautical mile is longer than a statute mile — roughly 1.15 times — so the two are not interchangeable on a chart.

Traditional surveying

The link and the chain come from Gunter's chain, a surveying instrument of 66 feet divided into 100 links. It looks arbitrary until you notice that ten square chains make exactly one acre, which is why land records in Britain, the United States, and much of the Commonwealth were kept in chains for centuries. Old deeds and property surveys are still written this way.

Worked Examples

A person 5 feet 10 inches tall — that is 70 inches, which converts to 177.8 centimeters exactly, since an inch is exactly 25.4 mm.
A 26.2 mile marathon — about 42.195 kilometers, the official distance.
A ship at 12 knots for 3 hours — 36 nautical miles, which is roughly 41.4 statute miles or 66.7 kilometers.
A visible light wavelength of 550 nanometers — 5,500 angstroms, the unit conventionally used in spectroscopy.
A plot of land 3 chains wide — 198 feet, or 66 yards.

Common Uses

Reading international specifications — component dimensions and technical drawings that arrive in the other system.
Travel and navigation — converting road distances, altitudes, and chart distances.
Construction and DIY — reconciling materials sold in metric sizes with plans drawn in feet and inches.
Science and engineering — moving between micrometers, nanometers, and angstroms at small scales.
Property and land records — interpreting older deeds written in chains and links.
Sport — comparing race distances recorded in miles and kilometers.

Things Worth Knowing

A mile is not a nautical mile. The difference is about 15%, which is more than enough to matter over any real distance.
US survey feet differ slightly from international feet. The gap is roughly two parts per million — irrelevant for a room, significant across a state. The US officially retired the survey foot in 2022.
Precision is not the same as accuracy. Converting a measurement rounded to the nearest foot into four-decimal-place centimeters does not make it more exact; the uncertainty of the original measurement carries through.
Watch the abbreviations. A lowercase "m" is a meter, "mi" is a mile, and "mm" is a millimeter — three quantities that differ by many orders of magnitude.

Frequently Asked Questions

How many centimeters are in an inch?

Exactly 2.54. This is a defined value rather than a measured one, agreed internationally in 1959, so the conversion is exact in both directions.

Why is a nautical mile longer than a mile?

Because it is defined geographically rather than historically. One nautical mile is one minute of latitude, which makes distance and position directly related on a chart. A statute mile descends from the Roman mille passus, a thousand paces, with no connection to the size of the Earth.

What is an angstrom used for?

Atomic and molecular distances. One angstrom is 0.1 nanometers, which happens to be about the diameter of a hydrogen atom, so bond lengths and crystal spacings come out as convenient small numbers.

Is a UK mile the same as a US mile?

Yes. Both are 1,609.344 meters. The systems diverge for units of volume, such as pints and gallons, but not for length.

Are the results rounded?

Results are computed at full floating-point precision and displayed to a practical number of digits. For everyday work the displayed value is exact enough; for metrology, apply the tolerance of your original measurement.