Converters

Length Converter

Convert between metric and imperial length units — millimeters, centimeters, meters, kilometers, inches, feet, yards and miles — with a full conversion table.

Converters · Length ConverterRuns in your browser

From

0.393701

1 cm = 0.393701 in

Unit	1 cm =
Millimeters	10 mm
Centimeters	1 cm
Meters	0.01 m
Kilometers	0.00001 km
Inches	0.393701 in
Feet	0.032808 ft
Yards	0.010936 yd
Miles	0.000006 mi
Nautical miles	0.000005 nmi

How to use the length converter

Type the measurement into the From box. The field accepts decimals and negative values, and starts at 1.
Pick the unit you are converting from in the dropdown underneath it — centimeters are selected by default.
Choose the target unit on the right; inches are preselected, so cm → in works without touching anything.
Read the bold result, then scroll to the table to see the same length in all nine units at once.
Hit the swap button between the two columns to reverse the direction without retyping the number.

The nine units and how they are defined

Every conversion on this page passes through the meter. The four metric units are plain powers of ten, and the five non-metric ones carry exact definitions: since the 1959 international yard and pound agreement an inch is exactly 0.0254 m, a foot is 12 inches, a yard is 3 feet and a statute mile is 1,760 yards, which is 1,609.344 m. The nautical mile was fixed at exactly 1,852 m by international agreement in 1929. The converter stores these exact factors, so nothing is rounded before the final display.

Unit	Symbol	Meters
Millimeters	mm	0.001
Centimeters	cm	0.01
Meters	m	1
Kilometers	km	1,000
Inches	in	0.0254
Feet	ft	0.3048
Yards	yd	0.9144
Miles	mi	1,609.344
Nautical miles	nmi	1,852

Units offered in the dropdowns and their value in meters.

How the conversion is calculated

The arithmetic is one multiplication and one division: the value is multiplied by the meter factor of the source unit and divided by the meter factor of the target unit. Take 5 km to miles. Multiplying 5 by 1,000 gives 5,000 m; dividing 5,000 by 1,609.344 gives 3.10686, which the widget prints as 3.1069. A small example works the same way: 0.5 mm is 0.0005 m, and 0.0005 ÷ 0.0254 = 0.019685 inches.

Because the same raw input feeds every row of the table, the nine values underneath the result are mutually consistent; they are not derived from the rounded headline figure.

How many decimals the result shows

Results are trimmed for readability according to their size, and trailing zeros are dropped. Thousands separators and the decimal mark follow your browser's language setting, so a German browser shows 1.609,34 where an English one shows 1,609.34.

Anything smaller than 0.0000005 collapses to 0 on screen: half a millimeter in miles is 0.00000031, and the table simply prints 0. Convert a larger quantity (500 mm instead of 0.5 mm) and move the decimal point yourself.
The rounding is only cosmetic. Internally the figure keeps full double-precision accuracy, so a chain of conversions is not degraded by the display.

Size of the result	Decimals kept	Example
100 or more	2	1 mi = 1,609.34 m
Between 1 and 100	4	1 nmi = 1.1508 mi
Less than 1	6	1 ft = 0.000305 km

Display precision applied by the converter.

Decimal feet, not feet and inches

The converter returns each unit as a single decimal number. A height of 1.75 m therefore comes out as 5.7415 ft rather than 5 ft 9 in. To split it, keep the whole feet (5) and multiply the remainder by 12: 0.7415 × 12 = 8.9 in, so roughly 5 ft 9 in. The same trick turns decimal miles into miles and yards (multiply the fraction by 1,760).

Units you will not find in the list include microns, furlongs, chains, fathoms and light-years. For those, convert to meters here and apply the missing factor by hand (a fathom is exactly 1.8288 m, a furlong 201.168 m).

Situations where the full table helps

Reading foreign product listings: a 55 cm carry-on comes back as 21.65 in, 1.8045 ft and 0.6015 yd in one pass.
Sailing and flying: 20 nautical miles is 37.04 km or 23.016 statute miles, and the table shows both without a second lookup.
DIY and 3D printing: 3 mm wall thickness is 0.1181 in, handy when a drawing mixes units.
Negative inputs are accepted, which is useful for differences such as a −15 mm tolerance (−0.5906 in).

Frequently asked questions

How many centimeters are in an inch?

There are exactly 2.54 centimeters in one inch. To convert inches to centimeters, multiply by 2.54; to go the other way, divide by 2.54.

How do I convert kilometers to miles?

Multiply the number of kilometers by 0.621371 to get miles. For example, 10 km × 0.621371 ≈ 6.21 miles.

Why does the converter give decimal feet instead of feet and inches?

Each unit is reported as one number. Multiply the fractional part of the feet value by 12 to recover the inches: 5.7415 ft is 5 ft plus 0.7415 × 12 ≈ 8.9 in.

What is the difference between a mile and a nautical mile?

A statute mile is 1,609.344 m; a nautical mile is 1,852 m, originally one minute of latitude. One nautical mile is about 1.1508 statute miles, and the table lists both.

Does rounding in the display affect the stored value?

No. Only the printed number is trimmed (2, 4 or 6 decimals depending on size). The calculation itself uses the exact factors and full floating-point precision.

Can I convert a negative or zero length?

Yes. Zero gives 0 in every row, and negative numbers convert normally, which is useful for offsets and tolerances. There is no validation beyond requiring a finite number.

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