Length Converters
Convert length and distance between meters, feet, inches, kilometers, miles, yards, and 50+ units. Used worldwide in construction, engineering, navigation, and everyday measurements. See also our CM to Inches, Meters to Feet, and KM to Miles converters.
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Popular Length Converters:
What is a Length Converter?
A length converter is a tool that converts measurements between different units of length and distance such as meters, feet, inches, kilometers, and miles. It is essential for international trade, construction, science, and everyday tasks where different measurement systems are used.
History of Length Measurement
Length measurement dates back to ancient civilizations who used body parts like the cubit (forearm length) and foot as units. The metric system was established in France in 1799, defining the meter as one ten-millionth of the distance from the equator to the North Pole. Today, the International System of Units (SI) defines the meter based on the speed of light.
About This Length Converter
This length converter supports over 50 units including meters, kilometers, centimeters, millimeters, miles, yards, feet, inches, nautical miles, light years, and more. It handles both metric (SI) and imperial/US customary units with high precision for scientific, engineering, and everyday use.
Understanding Length and Distance Measurement
Length is one of the most fundamental physical quantities — it describes how far apart two points are in space. From measuring fabric for a dress to calculating the distance between cities, length conversion is something people encounter daily. The challenge is that two major measurement systems coexist worldwide: the metric system (used by most countries) and the imperial/US customary system (used primarily in the United States, Liberia, and Myanmar).
The metric system builds all length units from a single base — the meter — using decimal prefixes. One kilometer is exactly 1,000 meters, one centimeter is exactly 0.01 meters, and so on. This regularity makes metric-to-metric conversions straightforward: just shift the decimal point. The imperial system, by contrast, uses irregular relationships: 12 inches in a foot, 3 feet in a yard, 1,760 yards in a mile. Converting between imperial units requires memorizing these specific factors, and converting between metric and imperial requires knowing the defined bridge values (1 inch = 25.4 mm exactly).
How to Convert Between Length Units (Step-by-Step)
Every length conversion follows the same basic principle: multiply your value by a conversion factor. The conversion factor tells you how many of the target unit equal one of the source unit. Here is the general method:
- Identify the source unit (what you have) and the target unit (what you need).
- Find the conversion factor between the two units. For example, 1 meter = 3.28084 feet, so the factor from meters to feet is 3.28084.
- Multiply your value by the conversion factor: result = value × factor.
- If the factor is not directly available, chain through a common unit. For example, to convert miles to centimeters: miles → meters (×1609.344) → centimeters (×100).
- Double-check your answer makes sense — converting to a smaller unit should give a larger number, and vice versa.
Essential Length Conversion Formulas
These are the most frequently used conversion relationships. All factors below are exact or rounded to 6 significant figures:
- 1 inch = 2.54 centimeters (exact, by definition)
- 1 foot = 12 inches = 30.48 centimeters (exact)
- 1 yard = 3 feet = 0.9144 meters (exact)
- 1 mile = 5,280 feet = 1,609.344 meters (exact)
- 1 kilometer = 1,000 meters = 0.621371 miles
- 1 meter = 100 centimeters = 3.28084 feet
- 1 nautical mile = 1,852 meters = 1.15078 statute miles
- 1 micrometer (micron) = 0.001 millimeters = 0.0000394 inches
Worked Examples — Length Conversions
Example 1: A room measures 4.5 meters in length. How long is that in feet and inches?
Solution:
We know 1 meter = 3.28084 feet.
Multiply: 4.5 × 3.28084 = 14.76378 feet.
The whole part is 14 feet. The decimal 0.76378 feet needs converting to inches.
0.76378 × 12 = 9.17 inches.
Answer: 4.5 meters = 14 feet 9.17 inches (approximately 14 ft 9 in).
Example 2: A marathon is 26.2 miles. What is that distance in kilometers?
Solution:
We know 1 mile = 1.609344 kilometers.
Multiply: 26.2 × 1.609344 = 42.165 km.
Answer: 26.2 miles = 42.165 kilometers. (The official marathon distance is 42.195 km.)
Example 3: A machinist needs to drill a hole 3/8 inch in diameter. What is that in millimeters?
Solution:
First convert the fraction: 3/8 = 0.375 inches.
We know 1 inch = 25.4 millimeters (exact).
Multiply: 0.375 × 25.4 = 9.525 mm.
Answer: 3/8 inch = 9.525 mm exactly.
Example 4: An international shipping container is 6.058 meters long. Express this in feet.
Solution:
We know 1 meter = 3.28084 feet.
Multiply: 6.058 × 3.28084 = 19.875 feet.
This confirms the standard 20-foot container specification.
Answer: 6.058 meters ≈ 19.875 feet (standard 20-ft shipping container).
Example 5: A bacterium is 2 micrometers long. How many nanometers is that?
Solution:
1 micrometer = 1,000 nanometers (micro = 10⁻⁶, nano = 10⁻⁹, difference = 10³).
Multiply: 2 × 1,000 = 2,000 nanometers.
Answer: 2 micrometers = 2,000 nanometers.
Quick Reference — Common Length Conversions
This table covers the most frequently looked-up length conversions. Bookmark this page for instant access.
| From | To |
|---|---|
| 1 inch | 2.54 cm |
| 1 foot | 30.48 cm |
| 1 yard | 0.9144 m |
| 1 mile | 1.609344 km |
| 1 meter | 3.28084 ft |
| 1 kilometer | 0.621371 mi |
| 1 centimeter | 0.3937 in |
| 1 millimeter | 0.03937 in |
| 1 nautical mile | 1.852 km |
| 1 light year | 9.461 × 10¹² km |
| 1 angstrom | 0.1 nm |
| 1 fathom | 1.8288 m |
| 1 furlong | 201.168 m |
| 1 league | 4.828 km |
Metric vs Imperial: Understanding the Two Length Systems
The metric system (formally the International System of Units, SI) was created during the French Revolution to replace the chaotic local measurement systems used across Europe. Its genius is simplicity: a single base unit (the meter) combined with decimal prefixes. Moving between kilometers, meters, centimeters, and millimeters requires only shifting a decimal point — no memorization of irregular factors needed.
The imperial and US customary systems evolved from English medieval units based on body parts (the foot), agricultural practices (the furlong = one furrow length), and Roman heritage (the mile from mille passus = 1,000 paces). While these units feel intuitive to those raised with them, their irregular relationships (12 inches per foot, 3 feet per yard, 5,280 feet per mile) make mental arithmetic difficult.
The bridge between systems is the inch–centimeter relationship: 1 inch = 2.54 centimeters exactly. This was internationally agreed in 1959 and forms the basis for all metric–imperial length conversions. From this single definition, every other cross-system conversion factor can be derived mathematically.
Where Length Conversion Matters
Construction & Architecture
Building plans may use metric in one country and imperial in another. A Canadian architect sending plans to a US contractor must convert all dimensions. A single error in conversion can mean doors that do not fit or walls that are the wrong height.
International Shipping & Trade
Shipping containers are measured in feet (20-ft and 40-ft standards), but cargo dimensions may be specified in meters. Calculating whether goods fit requires accurate conversion. Customs forms in different countries may require different units.
Athletics & Sports
Track events use meters (100m, 400m, 1500m) but American football uses yards, and road races may be advertised in either miles or kilometers. Athletes training internationally must convert pace and distance constantly.
Manufacturing & Machining
Precision parts may be specified in millimeters (metric countries) or thousandths of an inch (US/UK). A tolerance of ±0.05 mm requires knowing that equals ±0.002 inches. Getting this wrong means scrapped parts or failed assemblies.
Science & Engineering
Scientific papers use SI units exclusively, but engineering in the US often uses feet, pounds, and BTU. Space missions have failed due to metric–imperial confusion (NASA Mars Climate Orbiter, 1999 — thrust data in pound-seconds was read as newton-seconds).
Travel & Navigation
Road signs show kilometers in most countries but miles in the US, UK, and Myanmar. Nautical and aviation navigation uses nautical miles (1 NM = 1 minute of latitude). Pilots and sailors must convert between these systems fluently.
Common Mistakes in Length Conversion
The most frequent error is confusing the direction of multiplication. If 1 meter = 3.28 feet, then to convert feet to meters you divide by 3.28 (not multiply). A helpful rule: if you are converting to a larger unit, the number should get smaller. Another common mistake is mixing up statute miles and nautical miles — they differ by about 15%. Finally, in machining, people sometimes confuse millimeters and thousandths of an inch (mils): 1 mil = 0.0254 mm, not 1 mm.
The Metric Prefix System
The beauty of the metric system lies in its prefixes. Each prefix represents a power of 10: tera (10¹²), giga (10⁹), mega (10⁶), kilo (10³), base (10⁰), centi (10⁻²), milli (10⁻³), micro (10⁻⁶), nano (10⁻⁹), pico (10⁻¹²). For length, this means 1 kilometer = 1,000 meters = 100,000 centimeters = 1,000,000 millimeters. To convert between any two metric length units, simply count how many powers of 10 separate them and move the decimal point accordingly.
Key Takeaways
- The metric system uses decimal prefixes (kilo, centi, milli) — just move the decimal point to convert between metric units.
- The imperial system has irregular factors: 12 in/ft, 3 ft/yd, 5,280 ft/mi — memorize or look up these values.
- The bridge between systems: 1 inch = 2.54 cm exactly. All other cross-system factors derive from this.
- Converting to smaller units gives larger numbers; converting to larger units gives smaller numbers. Use this as a sanity check.
- For precision work (machining, science), always use the exact conversion factor, not a rounded approximation.
- When chaining conversions (e.g., miles → cm), multiply the factors together: 1 mile × 1609.344 m/mi × 100 cm/m = 160,934.4 cm.
Metric Conversion Factor Tables for Length Converter
| Units to convert | Multiply By The Number | Convert as Unit |
|---|---|---|
| CentiMeters (cm) | 0.03281 | Feet (ft) |
| CentiMeters (cm) | 0.3937007874 | Inches (in) |
| Cubic Meters | 35.3145 | Cubic Feet (ft) |
| KiloMeters (Km) | 0.62 | Miles (mi) |
| Meters (m) | 3.2808 | Feet (ft) |
| Meters (m) | 39.37007874 | Inches (in) |
| Meters (m) | 0.0006214 | Miles (mi) |
| Meters (m) | 1.0936 | Yards (yd) |
| MilliMeters (mm) | 0.03937007874 | Inches (in) |
| Feet (ft) | 0.3048 | Meters (m) |
| Inches (in) | 2.54 | CentiMeters (cm) |
| Inches (in) | 25.4 | MilliMeters (mm) |
| Miles (mi) | 1.609347 | KiloMeters (Km) |
| Yards (yd) | 0.9144 | Meters (m) |
Lengthconverters & it's abbreviations
| Unit | Abbreviation | Unit | Abbreviation | Unit | Abbreviation |
|---|---|---|---|---|---|
| meter | m | kilometer | km | decimeter | dm |
| centimeter | cm | millimeter | mm | micrometer | µm |
| nanometer | nm | mile | mi mi (Int) | yard | yd |
| foot | ft | inch | in | light year | ly |
| exameter | Em | petameter | Pm | terameter | Tm |
| gigameter | Gm | megameter | Mm | hectometer | hm |
| dekameter | dam | micron | µ | picometer | pm |
| femtometer | fm | attometer | am | megaparsec | Mpc |
| kiloparsec | kpc | parsec | pc | astronomical unit | AU UA |
| league (statute) | st. league | nautical league (int.) | nautical mile (UK) | NM | |
| nautical mile (international) | M NM or nmi | mile (statute) | mi mi (US) | mile (US survey) | mi |
| mile (Roman) | m.p | kiloyard | kyd | furlong | fur |
| chain | ch | rod | rd | fathom | fath |
| link | li | inch (US survey) | in | mil | mil thou |
| angstrom | A | fermi | F f | pica | p |
| point | p pt | twip | - | aln | aln |
| caliber | cl | centiinch | cin | ken | ken |
| Planck length | ℓP | Electron radius | - | Bohr radius | b a.u. |
| Earth equatorial radius | r earth | Earth polar radius | R E | Earth distance from sun | AU |
| Sun radius | - |
Frequently Asked Questions
How many centimeters are in an inch?
There are exactly 2.54 centimeters in one inch. This is a defined relationship — 1 inch is defined as exactly 25.4 millimeters (2.54 cm).
How do I convert kilometers to miles?
Multiply the number of kilometers by 0.621371 to get miles. For example, 10 km = 10 × 0.621371 = 6.21371 miles. Alternatively, divide kilometers by 1.60934.
What is the difference between a mile and a nautical mile?
A statute mile is 5,280 feet (1,609.344 meters). A nautical mile is 6,076 feet (1,852 meters) — about 15% longer. Nautical miles are used in aviation and maritime navigation because they correspond to one minute of latitude.
How many feet are in a meter?
There are approximately 3.28084 feet in one meter. Conversely, one foot equals 0.3048 meters exactly.
What is the smallest unit of length?
The Planck length (approximately 1.616 × 10⁻³⁵ meters) is the smallest meaningful unit of length in physics. In practical use, the femtometer (10⁻¹⁵ meters) is used to measure atomic nuclei.
Complete list of Length conversion units and its conversion.
- 1 centimeter [cm] = 0.01 meter [m]
cm to m → - 1 centimeter [cm] = 10 millimeter [mm]
cm to mm → - 1 centimeter [cm] = 0.032808399 foot [ft]
cm to feet →
- 1 centimeter [cm] = 10000 micrometer [µm]
cm to micrometer → - 1 centimeter [cm] = 0.0000062137 mile [mi, mi(Int)]
cm to miles → - 1 inch [in] = 25.4 millimeter [mm]
inches to mm →
- 1 inch [in] = 0.0277777778 yard [yd]
inches to yards → - 1 inch [in] = 0.0000254 kilometer [km]
inches to km → - 1 inch [in] = 25400 micrometer [µm]
inches to micrometer →
- 1 meter [m] = 39.37007874 inch [in]
meters to inches → - 1 meter [m] = 0.001 kilometer [km]
m to km → - 1 meter [m] = 1.0936132983 yard [yd]
meters to yards →
- 1 meter [m] = 10 decimeter [dm]
m to dm → - 1 foot [ft] = 30.48 centimeter [cm]
feet to cm → - 1 foot [ft] = 0.3048 meter [m]
feet to meters →
- 1 foot [ft] = 0.0003048 kilometer [km]
feet to km → - 1 foot [ft] = 304800 micrometer [µm]
feet to micrometer → - 1 kilometer [km] = 1000 meter [m]
km to m →
- 1 kilometer [km] = 1093.6132983 yard [yd]
km to yards → - 1 kilometer [km] = 1000000 millimeter [mm]
km to mm → - 1 kilometer [km] = 39370.07874 inch [in]
km to inches →
- 1 millimeter [mm] = 0.0393700787 inch [in]
mm to inches → - 1 millimeter [mm] = 0.000001 kilometer [km]
mm to km → - 1 millimeter [mm] = 0.0010936133 yard [yd]
mm to yards →
- 1 mile [mi, mi(Int)] = 5280 foot [ft]
miles to feet → - 1 mile [mi, mi(Int)] = 1760 yard [yd]
miles to yards → - 1 mile [mi, mi(Int)] = 63360 inch [in]
miles to inches →
- 1 yard [yd] = 3 foot [ft]
yards to feet → - 1 yard [yd] = 36 inch [in]
yards to inches → - 1 yard [yd] = 91.44 centimeter [cm]
yards to cm →
- 1 micrometer [µm] = 0.000001 meter [m]
micrometer to m → - 1 micrometer [µm] = 0.001 millimeter [mm]
micrometer to mm → - 1 micrometer [µm] = 0.0001 centimeter [cm]
micrometer to cm →
- 1 nanometer [nm] = 0.001 micrometer [µm]
nm to micrometer → - 1 nanometer [nm] = 0.0000001 centimeter [cm]
nm to cm → - 1 nanometer [nm] = 0.000000001 millimeter [mm]
nm to mm →
- 1 meter [m] = 100 centimeter [cm]
meters to cm → - 1 decimeter [dm] = 0.1 meter [m]
dm to m → - 1 decimeter [dm] = 10 centimeter [cm]
dm to cm →
- 1 light year [ly] = 5878625373183.608 mile [mi, mi(Int)]
light year to miles → - 1 nautical mile (international) = 1852 meter [m]
nautical mile to m → - 1 nautical mile (international) = 1.852 kilometer [km]
nautical mile to km →
- 1 parsec [pc] = 3.2615637769 light year [ly]
parsec to light year → - 1 angstrom [A] = 1e-10 meter [m]
angstrom to m → - 1 angstrom [A] = 0.1 nanometer [nm]
angstrom to nm →
- 1 astronomical unit [AU] = 92955807.273 mile [mi, mi(Int)]
AU to miles → - 1 dekameter [dam] = 10 meter [m]
dam to m → - 1 dekameter [dam] = 1000 centimeter [cm]
dam to cm →
- 1 picometer [pm] = 0.001 nanometer [nm]
pm to nm → - 1 femtometer [fm] = 1e-15 meter [m]
fm to m → - 1 femtometer [fm] = 0.001 picometer [pm]
fm to pm →
- 1 megameter [Mm] = 1000 kilometer [km]
Mm to km → - 1 gigameter [Gm] = 1000000000 meter [m]
Gm to m → - 1 gigameter [Gm] = 1000000 kilometer [km]
Gm to km →
- 1 centimeter [cm] = 0.3937007874 inch [in]
cm to inches → - 1 centimeter [cm] = 0.00001 kilometer [km]
cm to km → - 1 centimeter [cm] = 0.010936133 yard [yd]
cm to yards →
- 1 inch [in] = 0.0254 meter [m]
inches to meters → - 1 inch [in] = 0.0833333333 foot [ft]
inches to feet → - 1 inch [in] = 2.54 centimeter [cm]
inches to cm →
- 1 meter [m] = 100 centimeter [cm]
m to cm → - 1 meter [m] = 1000 millimeter [mm]
m to mm → - 1 meter [m] = 3.280839895 foot [ft]
meters to feet →
- 1 meter [m] = 0.0006213712 mile [mi, mi(Int)]
meters to miles → - 1 meter [m] = 1000000 micrometer [µm]
meters to micrometers → - 1 meter [m] = 1000000000 nanometer [nm]
meters to nanometers →
- 1 foot [ft] = 12 inch [in]
feet to inches → - 1 foot [ft] = 304.8 millimeter [mm]
feet to mm → - 1 foot [ft] = 0.3333333333 yard [yd]
feet to yards →
- 1 kilometer [km] = 0.6213711922 mile [mi, mi(Int)]
km to miles → - 1 kilometer [km] = 100000 centimeter [cm]
km to cm → - 1 kilometer [km] = 3280.839895 foot [ft]
km to feet →
- 1 millimeter [mm] = 0.001 meter [m]
mm to m → - 1 millimeter [mm] = 0.1 centimeter [cm]
mm to cm → - 1 millimeter [mm] = 0.0032808399 foot [ft]
mm to feet →
- 1 millimeter [mm] = 1000 micrometer [µm]
mm to micrometer → - 1 mile [mi, mi(Int)] = 1609.344 meter [m]
miles to meters → - 1 mile [mi, mi(Int)] = 1.609344 kilometer [km]
miles to km →
- 1 mile [mi, mi(Int)] = 160934.4 centimeter [cm]
miles to cm → - 1 mile [mi, mi(Int)] = 1609344 millimeter [mm]
miles to mm → - 1 yard [yd] = 0.9144 meter [m]
yards to meters →
- 1 yard [yd] = 914.4 millimeter [mm]
yards to mm → - 1 yard [yd] = 0.0009144 kilometer [km]
yards to km → - 1 yard [yd] = 0.0005681818 mile [mi, mi(Int)]
yards to miles →
- 1 micrometer [µm] = 1000 nanometer [nm]
micrometer to nm → - 1 micrometer [µm] = 0.0000393701 inch [in]
micrometer to inches → - 1 nanometer [nm] = 1e-9 meter [m]
nm to m →
- 1 meter [m] = 1000000000 nanometer [nm]
m to nm → - 1 millimeter [mm] = 1000000 nanometer [nm]
mm to nm → - 1 centimeter [cm] = 10000000 nanometer [nm]
cm to nm →
- 1 decimeter [dm] = 100 millimeter [mm]
dm to mm → - 1 light year [ly] = 9460730472580000 meter [m]
light year to m → - 1 light year [ly] = 9460730472580 kilometer [km]
light year to km →
- 1 nautical mile (international) = 1.150779448 mile [mi, mi(Int)]
nautical mile to miles → - 1 nautical mile (international) = 6076.1154856 foot [ft]
nautical mile to feet → - 1 parsec [pc] = 3.08567758128e+16 meter [m]
parsec to m →
- 1 angstrom [A] = 1e-8 centimeter [cm]
angstrom to cm → - 1 astronomical unit [AU] = 149597870691 meter [m]
AU to m → - 1 astronomical unit [AU] = 149597870.691 kilometer [km]
AU to km →
- 1 hectometer [hm] = 100 meter [m]
hm to m → - 1 hectometer [hm] = 328.0839895 foot [ft]
hm to feet → - 1 picometer [pm] = 1e-12 meter [m]
pm to m →
- 1 attometer [am] = 1e-18 meter [m]
am to m → - 1 attometer [am] = 0.001 femtometer [fm]
am to fm → - 1 megameter [Mm] = 1000000 meter [m]
Mm to m →
- 1 terameter [Tm] = 1000000000000 meter [m]
Tm to m → - 1 terameter [Tm] = 1000000000 kilometer [km]
Tm to km →