Convert length or distance between nanometres, micrometres, millimetres, centimetres, metres, kilometres, inches, feet, yards, miles.
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Length & Distance
Convert length and distance between metric and imperial units
Enter a value and choose a unit to see all equivalents at once — nanometres, micrometres, millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles.
Common conversion shortcuts
This keeps the broad length-converter workflow fast for the common search intents: cm to inches, metres to feet, feet to metres, and kilometres to miles.
Result
3.28084 ft
1 m equals 3.28084 ft. That length equals 100 cm, 3.28084 ft, 0.000621 mi, and 0.00054 nmi.
Metres
1
Feet
3.28084
Miles
0.000621
Feet + inches
3 ft 3.4 in
Metric
Nanometres1,000,000,000 nm
Micrometres1,000,000 µm
Millimetres1,000 mm
Centimetres100 cm
Metres1 m
Kilometres0.001 km
Imperial
Inches39.3701 in
Feet3.28084 ft
Yards1.09361 yd
Miles0.000621 mi
Popular conversions for this length
These pairs cover the most common length-converter searches, so you can read the broad all-units sheet and the high-intent comparisons from the same run.
Pair
Left side
Right side
Typical use
Centimetres ↔ inches
100 cm
39.3701 in
Useful for screens, products, and body measurements.
Metres ↔ feet
1 m
3.28084 ft
Useful for room sizes, building dimensions, and altitude references.
Kilometres ↔ miles
0.001 km
0.000621 mi
Useful for road distance, running, and route planning.
Nautical miles ↔ kilometres
0.00054 nmi
0.001 km
Useful for aviation and marine distance checks.
Full conversion sheet
Metric, imperial, and nautical outputs stay together here, with a note on where each unit is usually most useful.
Unit
Value
Group
Typical use
Nanometres
1,000,000,000 nm
Metric
Optics, chip features, wavelengths, and microscopic measurements.
Micrometres
1,000,000 µm
Metric
Microscopy, machining tolerances, and fine material thickness.
Millimetres
1,000 mm
Metric
Precision drawings, manufacturing, and small-part measurements.
Centimetres
100 cm
Metric
Household dimensions, body measurements, and product sizing.
Metres
1 m
Metric
Room, building, and everyday object dimensions.
Kilometres
0.001 km
Metric
Road distance, route planning, and race lengths.
Inches
39.3701 in
Imperial
Screens, consumer products, and US sizing.
Feet
3.28084 ft
Imperial
Room height, construction, and altitude references.
Yards
1.09361 yd
Imperial
Sport fields, golf, and fabric measurement.
Miles
0.000621 mi
Imperial
Road travel and route planning in imperial contexts.
Length unit conversion: metres, feet, miles, and all the in-between explained
A length converter lets you switch any distance or dimension between metric and imperial units instantly. This page also explains the main assumptions behind the length unit conversion result, highlights the supporting figures shown by the calculator, and helps the reader use the estimate without overstating what a quick online tool can prove.
Metric and imperial length units compared
The metric system builds every length unit around powers of ten. One centimetre is one hundredth of a metre; one kilometre is one thousand metres. That makes arithmetic straightforward: moving between metric units is just multiplication or division by 10, 100, or 1,000. The imperial system works differently, using historically defined units that share no consistent ratio — 12 inches in a foot, 3 feet in a yard, 1,760 yards in a mile — which is precisely why a converter is so useful.
In practice, most countries use metric for almost everything, while the United States continues to use imperial for everyday distances (miles, feet, inches) and a handful of other countries use imperial for particular contexts such as aviation altitude in feet or body height in feet and inches. A free online length converter bridges those two systems without any mental arithmetic.
The exact conversion factors used by this converter
Every conversion in this tool is derived from a single base unit: the metre. The tool converts the input into metres first and then divides by the target unit factor to reach the final value. All factors here are exact definitions rather than approximations, as set out in international measurement standards.
One inch is defined as exactly 2.54 centimetres — a definition that has been internationally agreed since 1959. Every other imperial unit follows from that: one foot is 12 inches, giving exactly 0.3048 metres; one yard is 3 feet, giving 0.9144 metres; one international mile is 1,760 yards, giving 1,609.344 metres exactly. The smaller metric units follow SI prefixes: one micrometre is one-millionth of a metre and one nanometre is one-billionth of a metre.
1 inch = 2.54 cm (exact)
The internationally defined relationship between the inch and the centimetre, agreed in 1959.
1 foot = 12 inches = 0.3048 m (exact)
The exact metric equivalent of one foot, derived from the inch definition.
1 mile = 1,760 yards = 1,609.344 m (exact)
The exact metric equivalent of one international mile.
1 nautical mile = 1,852 m (exact)
The international nautical mile, used in aviation and marine navigation.
1 µm = 0.000001 m and 1 nm = 0.000000001 m
SI-prefix relationships used for microscopy, wavelengths, chip features, and other small-scale measurements.
When each unit is most useful
Nanometres and micrometres are used when ordinary millimetres are too large to describe the thing being measured: optics, wavelengths, microscopy, semiconductor features, coatings, machining tolerances, and fine material thickness. Millimetres are used in precision manufacturing, engineering drawings, small-scale craft, and medical contexts where fine measurement matters. Centimetres appear in everyday measurement tasks in metric countries — clothing sizes, room dimensions, human height. Metres cover most everyday distances from the length of a room to the height of a building. Kilometres handle longer distances: road distances, city separations, marathon race lengths.
Inches remain the dominant unit in the United States and Canada for construction, screen sizes, tyre widths, and body height. Feet are used for building dimensions, ceiling heights, and altitude in aviation. Yards survive mainly in American football, golf, and fabric measurement. Miles are the standard road-distance unit in the UK and the United States. Nautical miles are the standard for marine and aviation distance, equal to one minute of latitude on the Earth's surface.
Screen sizes are measured diagonally in inches across most of the world.
Aviation altitude is almost universally reported in feet regardless of metric adoption.
GPS coordinates use decimal degrees, but route distances use km or miles by region.
Running races (5K, 10K, half-marathon, marathon) use metric even in the United States.
Using this length converter for common tasks
To convert centimetres to inches, enter the value in centimetres, choose centimetres as the source unit, and set inches as the target unit — the equivalent appears in the headline while the full table remains available below. The converter is useful for any everyday unit switch: checking whether a product listed in inches will fit a space measured in centimetres, converting a road distance from miles to kilometres before a trip, or understanding a height given in feet and inches as a centimetre measurement.
For tasks that require very high precision such as engineering tolerances, use the scientific-notation output this converter provides for very small or very large values. For everyday tasks like room planning, the regular decimal output is precise enough.
Enter 1 and choose miles as the source unit. The converter first turns 1 mile into the exact metre definition of 1,609.344 m, then divides by the target unit factors. That gives 1.609344 km, 5,280 ft, and 1,760 yd without needing separate calculations.
This is why grouped output is useful. A route, product specification, or planning note often needs more than one target unit at the same time, and seeing kilometres, feet, and nautical miles together is faster than running several separate conversions.
Direct from-to answers plus a full unit sheet
Many length conversion searches are direct pairs: cm to inches, inches to cm, meters to feet, feet to meters, km to miles, or miles to km. The target-unit selector answers that pair immediately, while the swap control reverses the conversion without retyping the number.
The full conversion sheet is still useful because real tasks rarely stay in one pair. A product dimension might need inches for a vendor spec, centimetres for a shelf label, and metres for a room plan. A route length might be read as miles, kilometres, and nautical miles depending on whether the context is road travel, maps, or navigation.
Common length conversion searches
Most people search for a length converter because they need one of the same few conversions: feet to cm, cm to feet and inches, miles to km, inches to metres, or metres to feet. Showing every equivalent at once makes it easier to compare metric and imperial values without repeating the calculation or guessing at rounded conversions.
That is especially useful when a number has to match a product spec, planning document, or construction measurement exactly. Using the exact definitions for inch, foot, yard, mile, and nautical mile keeps the conversion stable whether you are working on body height, room dimensions, travel distances, or navigation notes.
Further reading
NIST — Unit Conversion — NIST reference page for exact unit-conversion relationships and SI use.
When a general length converter is the right tool
A general length converter is best when the question is broadly about unit translation rather than a specialist workflow. It works well for product dimensions, room sizes, route lengths, material cut lists, package measurements, map distances, and quick checks between metric and imperial units.
If the intent is specifically human height, a height converter is often more useful because it can show a feet-and-inches composite built for forms and body-measurement contexts. If the intent is specifically marine or aviation navigation, a nautical-distance converter is often better because it keeps route legs anchored to nautical-mile conventions. This page owns the broader length converter intent: one input, one grouped sheet, and the common cm/in, m/ft, and km/mi comparisons most people actually need.
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54 centimetres. This is an internationally defined exact value, not an approximation. One inch equals 2.54 cm, so one centimetre equals approximately 0.3937 inches.
How many kilometres are in a mile?
Exactly 1.609344 kilometres. One mile equals 1,760 yards, each yard being 0.9144 metres, giving a total of 1,609.344 metres or 1.609344 kilometres.
What is a nautical mile and how does it compare to a regular mile?
A nautical mile is 1,852 metres, defined as one minute of arc along a meridian of the Earth. One nautical mile is approximately 1.15078 statute (land) miles or about 1.852 kilometres. It is the standard distance unit for marine navigation and aviation.
How do I convert feet and inches to centimetres?
Convert the feet to inches first, add the remaining inches, then multiply the total inches by 2.54. The converter handles that workflow automatically and shows the metric equivalents together.
Why does the converter show nautical miles too?
Nautical miles are a standard navigation unit used in aviation and marine contexts. Including them makes the converter more useful for route planning and chart-based distance work.
How many feet are in a metre?
Exactly 3.280839895 feet. Because one foot is defined as exactly 0.3048 metres, dividing 1 by 0.3048 gives the exact metre-to-foot relationship.
What is 6 feet in metres?
Six feet equals 1.8288 metres exactly, because 6 × 0.3048 = 1.8288. The same value is 182.88 centimetres.
Is a general length converter the same as a height converter?
Not quite. A general length converter is built for broad unit translation across distance and dimension work. A height converter is better when the intent is body height, because it usually surfaces feet-and-inches composite output and form-ready rounding more directly.
Can I convert micrometres or nanometres with this length converter?
Yes. The converter supports micrometres (µm) and nanometres (nm) as metric length units. These are useful for microscopy, wavelengths, coatings, chip features, and other very small measurements where millimetres or centimetres would be too coarse.
What is the fastest way to convert cm to inches or km to miles?
Use the common-pair shortcuts above the input. They preselect the source and target units for high-frequency searches such as cm to inches, inches to cm, metres to feet, feet to metres, km to miles, and miles to km, while still showing the broader conversion table.
