0.00001 km, because one hundred thousand centimetres make one kilometre. The pattern holds at every size: 5 cm is 0.00005 km, 50 cm is 0.0005 km, 250 cm is 0.0025 km, 1,000 cm is 0.01 km and 10,000 cm is 0.1 km. The conversion moves the decimal point five places to the left; the displayed result may round longer inputs to twelve significant digits.

What is the formula for cm to km?

Kilometres = centimetres / 100,000, and centimetres = kilometres × 100,000 in the other direction. Centi means a hundredth of a metre and kilo means a thousand metres, so the gap between the two prefixes is 100 × 1,000, which is 100,000 exactly. Nothing in that number is an approximation, so 500,000 cm comes back as 5 with nothing trailing after the decimal point.

How many centimetres are in a kilometre?

Exactly 100,000. Half a kilometre is 50,000 cm, 0.4 km is 40,000 cm and 1.5 km is 150,000 cm. A statute mile is 1,609.344 m by definition, which is 160,934.4 cm, and the converter reads that back as 1.609344 km.

Can I convert kilometres back to centimetres on this page?

Yes. Press the Swap units button between the two boxes and the pair reverses without a reload: type 1 and the answer is 100,000 cm, and 0.4 km reads as 40,000 cm. Both unit menus stay open too, so the same number will go from centimetres to millimetres, metres, inches, feet or miles without leaving the page.

Does dividing by 100,000 also work for square centimetres?

No, and this is where the mistake usually happens. Area squares the ratio, so one square kilometre is 100,000² square centimetres, which is 10,000,000,000 cm², and one square centimetre is 0.0000000001 km². Use the Area category chip above the converter for that: square centimetres and square kilometres are both in its list, along with square metres, hectares, acres, square feet and square miles.

Why does the page open on cm and km when I last converted something else?

This focused page opens on Centimetre and Kilometre, while preserving the main converter’s saved unit pair. When storage is usable, a saved value and uncommon-unit preference can travel between pages. Its suffix must still match the current From unit. Valid deliberate scalar edits can save those fields after a short delay; invalid or incomplete drafts do not overwrite the saved record. Unusable or conflicting records are kept with an explanation until you use Forget saved settings, which keeps the current conversion on screen.

How precise is the answer, and can I copy it?

The converter divides the decimal-rational input by the exact factor 100,000, then rounds the displayed output to twelve significant digits with trailing zeros dropped. Thus 100,000 cm displays as 1 km, and 100 cm in the Mile row as 0.000621371192237 mi. Copy result and row buttons copy that rounded number without grouping commas; Copy complete conversion also identifies the input, units and conventions. Clipboard refusal leaves a selectable current summary. The From box accepts a single decimal or scientific number and a matching unit suffix, with properly grouped thousands; decimal commas, fractions and compound measurements are refused.

What is the same distance in metres, feet or miles?

The list under the answer already has it, because the converter works out every common length unit at once rather than one target at a time. Type 100 in the From box and it reads 0.001 km in the headline, 1 m for metres, 1,000 mm for millimetres, 39.3700787402 in for inches, 3.28083989501 ft for feet and 1.09361329834 yd for yards. Seven rarer length units, including micrometres, furlongs, light years and parsecs, sit behind the Show 7 more switch in the readout.

CM to KM Converter

A kilometre is exactly 100,000 centimetres, so centimetres to kilometres is one division: km = cm / 100,000. In decimal that is the point moving five places to the left, which is why 1 cm is 0.00001 km, 100 cm is 0.001 km, 10,000 cm is 0.1 km and 100,000 cm is 1 km. Both units are defined from the metre, a centimetre as a hundredth of it and a kilometre as a thousand of them, so the ratio is exact rather than measured. Displayed answers round to twelve significant digits, and results smaller than a millionth of a kilometre switch to exponential notation, so 0.1 cm reads 0.000001 while 0.05 cm reads 5e-7. This page opens the converter with Centimetre in the From box and Kilometre in the To box, whatever pair you converted last, and lists the same distance in millimetres, metres, inches, feet, yards, miles and nautical miles under the answer.

From

To0.00001

Category: Length

Base unit: meter

Uncommon units: Show 7 more

Feet, yards and miles use international definitions. A light year uses a 365.25-day Julian year; the parsec coefficient is approximate.

Results round to 12 significant digits using the listed unit definitions. Input must have a finite numeric magnitude and at most 512 significant digits. Type a single decimal or scientific number; a matching From unit suffix is accepted. Commas and grouped spaces separate thousands; decimal commas, fractions and compound measurements are refused.

1 cm in every length unit

Millimetermm
10
Meterm
0.01
Kilometerkm
0.00001
Inchin
0.393700787402
Footft
0.0328083989501
Yardyd
0.0109361329834
Milemi
0.00000621371192237
Nautical milenmi
0.00000539956803456

Selectable complete conversion

Unit Converter — Length
Input: 1 (Centimeter, cm)
Result: 0.00001 km (Kilometer)
Displayed values round to 12 significant digits.
Feet, yards and miles use international definitions. A light year uses a 365.25-day Julian year; the parsec coefficient is approximate.
All other units:
Nanometer (nm): 10000000
Micrometer (µm): 10000
Millimeter (mm): 10
Meter (m): 0.01
Kilometer (km): 0.00001
Inch (in): 0.393700787402
Foot (ft): 0.0328083989501
Yard (yd): 0.0109361329834
Mile (mi): 0.00000621371192237
Nautical mile (nmi): 0.00000539956803456
Thou (mil): 393.700787402
Furlong (fur): 0.000049709695379
Astronomical unit (AU): 6.68458712227e-14
Light year (ly): 1.05700083402e-18
Parsec (pc): 3.24077928944e-19

Common questions

How many km is 1 cm?: 0.00001 km, because one hundred thousand centimetres make one kilometre. The pattern holds at every size: 5 cm is 0.00005 km, 50 cm is 0.0005 km, 250 cm is 0.0025 km, 1,000 cm is 0.01 km and 10,000 cm is 0.1 km. The conversion moves the decimal point five places to the left; the displayed result may round longer inputs to twelve significant digits.
What is the formula for cm to km?: Kilometres = centimetres / 100,000, and centimetres = kilometres × 100,000 in the other direction. Centi means a hundredth of a metre and kilo means a thousand metres, so the gap between the two prefixes is 100 × 1,000, which is 100,000 exactly. Nothing in that number is an approximation, so 500,000 cm comes back as 5 with nothing trailing after the decimal point.
How many centimetres are in a kilometre?: Exactly 100,000. Half a kilometre is 50,000 cm, 0.4 km is 40,000 cm and 1.5 km is 150,000 cm. A statute mile is 1,609.344 m by definition, which is 160,934.4 cm, and the converter reads that back as 1.609344 km.
Can I convert kilometres back to centimetres on this page?: Yes. Press the Swap units button between the two boxes and the pair reverses without a reload: type 1 and the answer is 100,000 cm, and 0.4 km reads as 40,000 cm. Both unit menus stay open too, so the same number will go from centimetres to millimetres, metres, inches, feet or miles without leaving the page.
Does dividing by 100,000 also work for square centimetres?: No, and this is where the mistake usually happens. Area squares the ratio, so one square kilometre is 100,000² square centimetres, which is 10,000,000,000 cm², and one square centimetre is 0.0000000001 km². Use the Area category chip above the converter for that: square centimetres and square kilometres are both in its list, along with square metres, hectares, acres, square feet and square miles.
Why does the page open on cm and km when I last converted something else?: This focused page opens on Centimetre and Kilometre, while preserving the main converter’s saved unit pair. When storage is usable, a saved value and uncommon-unit preference can travel between pages. Its suffix must still match the current From unit. Valid deliberate scalar edits can save those fields after a short delay; invalid or incomplete drafts do not overwrite the saved record. Unusable or conflicting records are kept with an explanation until you use Forget saved settings, which keeps the current conversion on screen.
How precise is the answer, and can I copy it?: The converter divides the decimal-rational input by the exact factor 100,000, then rounds the displayed output to twelve significant digits with trailing zeros dropped. Thus 100,000 cm displays as 1 km, and 100 cm in the Mile row as 0.000621371192237 mi. Copy result and row buttons copy that rounded number without grouping commas; Copy complete conversion also identifies the input, units and conventions. Clipboard refusal leaves a selectable current summary. The From box accepts a single decimal or scientific number and a matching unit suffix, with properly grouped thousands; decimal commas, fractions and compound measurements are refused.
What is the same distance in metres, feet or miles?: The list under the answer already has it, because the converter works out every common length unit at once rather than one target at a time. Type 100 in the From box and it reads 0.001 km in the headline, 1 m for metres, 1,000 mm for millimetres, 39.3700787402 in for inches, 3.28083989501 ft for feet and 1.09361329834 yd for yards. Seven rarer length units, including micrometres, furlongs, light years and parsecs, sit behind the Show 7 more switch in the readout.

Results round to 12 significant digits using the listed unit conventions. Many factors are exact definitions; psi and parsec use rounded coefficients. Temperature includes scale offsets. Days and weeks are fixed-duration units, and unit conversion does not determine calendar dates, ambient pressure or a software label’s convention.