Convert linear distance across SI and metric, imperial and US customary, navigation, scientific, and astronomical units.
Centimeter to Inch
ExactCategory meaning
Length is the one-dimensional distance between two points. Use this guide to choose among everyday, road, navigation, microscopic, and astronomical units without confusing linear length with area or volume.
Calculation method
Length units use fixed scale factors. A value can be expressed in meters, the SI base unit of length, and then rescaled into the target unit. Zero remains zero in every length unit, and reversing a conversion uses the reciprocal of the same relationship.
Where a standard defines an exact relationship—such as the international inch to the meter—the converter preserves that exact relationship and treats display rounding separately.
The standards listed on this page establish each unit’s relationship to the meter. The same reviewed relationships power the live converter, calculated examples, and reference values; display settings change only how the result is shown, never the underlying calculation.
About the converter’s methodologyChoose the right unit
Start with the measurement context, then select the symbol shown by the source. Every family below contains units compatible within this category.
Millimeters, centimeters, meters, inches, feet, and yards cover product sizes, drawings, rooms, construction, and other human-scale measurements.
Millimeter Centimeter Meter Inch Foot
See all 7 unitsKilometers and statute miles describe ordinary travel, while chains and furlongs remain useful in specific land contexts and nautical miles belong to navigation.
Kilometer Mile Nautical Mile Fathom
See all 9 unitsPicometers, nanometers, micrometers, and ångströms express dimensions that are inconveniently small in meters.
See all 4 unitsAstronomical units, light-travel distances, and parsec multiples describe scales from the Solar System to galaxies and cosmology.
Astronomical Unit Light Year Parsec
See all 10 unitsChoose a common direction and start with the units already selected.
Calculated examples
Each example is calculated from the same unit definitions used by the interactive converter, so the worked values stay consistent with the result above.
1 in = 2.54 cm
5 km ≈ 3.1068559612 mi
1 nmi = 1852 m
Avoid common mistakes
A mile used for road distance and a nautical mile used in navigation are different units. Select the one stated by the source rather than treating “mile” as interchangeable.
Defined relationships such as inch to centimeter are exact. Astronomical units involving evaluated constants retain their catalog accuracy disclosure instead of implying unlimited precision.
A meter, square meter, and cubic meter describe different quantities. Squaring or cubing a length conversion requires the matching Area or Volume category.
Unit field guide
These profiles focus on decisions that affect a real conversion: what the unit represents, where it appears, when to select it, and which similarly named quantity can produce the wrong result.
The meter is the SI base unit of length. Since 1983, it has been defined from the fixed numerical value of the speed of light in vacuum, making it the reference through which the other units in this guide are related.
The international inch is an imperial and US customary unit of length defined as exactly 25.4 millimeters. Twelve inches make one international foot, and thirty-six make one international yard.
1 in = 0.0254 m
A centimeter is one hundredth of a meter. It is a decimal metric unit, so ten millimeters make one centimeter and one hundred centimeters make one meter.
1 cm = 0.01 m
The international nautical mile is a navigation unit defined as exactly 1,852 meters. Its length differs from the statute mile used for ordinary land distance.
1 nmi = 1852 m
Compatible catalog
Every unit below measures linear length, so any two can be converted directly. The groups help you find a unit by the scale and setting in which it is commonly used.
Millimeter
Metric unit used for small dimensions, tolerances, and technical drawings.
mmCentimeter
Metric unit commonly used for body measurements and everyday dimensions.
cmMeter
SI base unit of length and the reference unit for this category.
mInch
International inch, defined as exactly 2.54 centimeters.
inFoot
International foot used in imperial and US customary measurements.
ftYard
Three international feet; common in fabric, sport, and land measurement.
ydMil / Thou
One thousandth of an inch, also called a thou; used for material thicknesses and manufacturing tolerances.
milPicometer
One trillionth of a meter; used for atomic-scale distances and bond lengths.
pmNanometer
One billionth of a meter; common for wavelengths, semiconductor features, and nanoscale structures.
nmMicrometer
One millionth of a meter, also called a micron; used for cells, particles, coatings, and fine tolerances.
µmÅngström
A tenth of a nanometer; traditionally used for atomic dimensions and electromagnetic wavelengths.
ÅAstronomical Unit
Distance unit used primarily within the Solar System.
auLight Second
Distance traveled by light in vacuum in one second.
light-sLight Minute
Distance traveled by light in vacuum in one minute.
light-minLight Hour
Distance traveled by light in vacuum in one hour.
light-hLight Day
Distance traveled by light in vacuum in one day.
light-dayLight Year
Distance traveled by light in vacuum during one Julian year.
lyParsec
Astronomical distance unit based on parallax geometry.
pcKiloparsec
One thousand parsecs; often used for distances within and around galaxies.
kpcMegaparsec
One million parsecs; commonly used for distances between galaxies.
MpcGigaparsec
One billion parsecs; used for very large cosmological distances.
GpcLength conversion helps when drawings, specifications, routes, or scientific observations use a different distance unit from the required result.
Helpful answers
The catalog includes compatible SI and other metric units, imperial and US customary units, navigation units, and selected astronomical distance units.
Yes. One international inch is defined as exactly 2.54 centimeters, so the relationship itself introduces no approximation.
The meter is the SI base unit of length and the reference unit for this category. Other supported length units are related to it by a fixed scale factor.
No. The international nautical mile is exactly 1,852 meters and is used in marine and aviation navigation. The statute mile used for ordinary land distance is a different length.
No. Length, area, and volume are different quantities. Area requires the length factor to be squared, and volume requires it to be cubed, so use the matching converter category.
No. A light-year is a length: the distance light travels in vacuum during one Julian year. The word “year” identifies the travel interval used to define that distance.
An exact relationship can produce a repeating decimal in one direction. The definition remains exact, but a screen must display a finite number of digits; round the final result to suit the source measurement and task.
