Length Unit Converter â cm, mm, inches, feet, meters, miles, more
Convert between any length units instantly. Centimeters to inches, meters to feet, miles to kilometers â all conversions update in real time as you type. Free, no signup.
Quick reference table
| Value | cm | inches |
|---|
Scientific and Specialty Length Units
Beyond everyday units, several specialty measurements appear in specific fields. The nautical mile (1,852 meters) is used in aviation and maritime navigation because it corresponds to one arc-minute of latitude, simplifying navigation calculations. The astronomical unit (AU) â 149,597,870.7 km â is the average Earth-Sun distance, used to describe distances within our solar system. A light-year (9.46 Ã 10^12 km) is the distance light travels in one year, used for interstellar distances.
In printing and typography, the point (pt) equals 1/72 of an inch (0.353mm) and the pica equals 12 points (4.233mm). These units still appear in CSS, font sizes, and desktop publishing software.
Construction and Architecture
In construction, the choice between metric and Imperial depends heavily on country. US construction uses feet and inches for all dimensions. European construction uses millimeters for precision work and meters for larger dimensions. A standard US door opening is 32 inches wide (81.28 cm). Standard ceiling height is 8 feet (243.84 cm) in the US, typically 250 cm in European construction.
Length Unit Systems: Imperial vs Metric
Most of the world uses the metric system â meters, centimeters, kilometers. Three countries still use Imperial units as primary measurement: the United States, Liberia, and Myanmar. The UK uses a hybrid â officially metric but with miles on road signs and a cultural attachment to feet and inches for personal height.
The conversion between systems isn't round numbers, which is why people reach for a converter: 1 inch is exactly 2.54 centimeters (this is the internationally agreed legal definition since 1959). From this single anchor, all other Imperial-to-metric length conversions derive.
The Conversions You'll Actually Use
| Common Conversion | Result | Rounded Rule of Thumb |
|---|---|---|
| 1 inch â cm | 2.54 cm | "2.5 cm per inch" |
| 1 foot â cm | 30.48 cm | "30 cm per foot" |
| 1 meter â feet | 3.281 ft | "Just over 3 feet" |
| 1 mile â km | 1.609 km | "Multiply miles à 1.6" |
| 1 km â miles | 0.621 mi | "Multiply km à 0.6" |
| 5 feet 10 inches â cm | 177.8 cm | Common male height reference |
| 100 km/h â mph | 62.1 mph | Speed limit reference for EU/US comparison |
Centimeters vs Inches for Everyday Use
The most frequent conversion people need is between centimeters and inches â for clothing sizes, screen sizes, furniture measurements, and anything bought from international retailers. A 32-inch TV screen is 81.28 cm. A US men's size 10 shoe has an insole of approximately 28 cm. A standard A4 paper sheet is 29.7 Ã 21 cm, equivalent to 11.69 Ã 8.27 inches.
For height: 6 feet is 182.88 cm. 170 cm is 5 feet 7 inches. The converter above handles height conversion automatically â enter feet and get centimeters, or enter centimeters and get feet and inches.
Kilometers to Miles for Road Distances
The fastest mental math approximation: multiply kilometers by 0.6 to get miles, or multiply miles by 1.6 to get kilometers. This is slightly off (the real factor is 0.621) but accurate enough for most driving estimates. A 100 km trip is about 62 miles. A 26.2-mile marathon is 42.2 km.
Frequently Asked Questions
What is the exact conversion between inches and centimeters?
By international agreement since 1959, 1 inch = 2.54 centimeters exactly. This is a defined value, not an approximation. From this: 1 foot = 30.48 cm, 1 yard = 91.44 cm, 1 mile = 1,609.344 m exactly.
How do I convert height from feet/inches to centimeters?
Convert feet to inches first (multiply by 12), add the remaining inches, then multiply total inches by 2.54. Example: 5 feet 9 inches = (5Ã12)+9 = 69 inches à 2.54 = 175.26 cm. The converter above handles this automatically.
What's the difference between a nautical mile and a regular mile?
A nautical mile is 1,852 meters (1.852 km), compared to a statute mile of 1,609.344 meters. Nautical miles are used in aviation and maritime navigation because one nautical mile corresponds to one arc-minute of latitude on Earth's surface, making navigation calculations simpler.
How accurate are the conversions on this tool?
All conversions use precise factors (not rounded approximations) internally. The displayed result is rounded to 6 decimal places where applicable. For scientific or engineering purposes, verify against official standards if extreme precision is required.
Length Unit Systems: Imperial vs Metric
Most of the world uses the metric system â meters, centimeters, kilometers. Three countries still use Imperial units as primary measurement: the United States, Liberia, and Myanmar. The UK uses a hybrid â officially metric but with miles on road signs and a cultural attachment to feet and inches for personal height.
The conversion between systems isn't round numbers, which is why people reach for a converter: 1 inch is exactly 2.54 centimeters (this is the internationally agreed legal definition since 1959). From this single anchor, all other Imperial-to-metric length conversions derive.
The Conversions You'll Actually Use
| Common Conversion | Result | Rounded Rule of Thumb |
|---|---|---|
| 1 inch â cm | 2.54 cm | "2.5 cm per inch" |
| 1 foot â cm | 30.48 cm | "30 cm per foot" |
| 1 meter â feet | 3.281 ft | "Just over 3 feet" |
| 1 mile â km | 1.609 km | "Multiply miles à 1.6" |
| 1 km â miles | 0.621 mi | "Multiply km à 0.6" |
| 5 feet 10 inches â cm | 177.8 cm | Common male height reference |
| 100 km/h â mph | 62.1 mph | Speed limit reference for EU/US comparison |
Centimeters vs Inches for Everyday Use
The most frequent conversion people need is between centimeters and inches â for clothing sizes, screen sizes, furniture measurements, and anything bought from international retailers. A 32-inch TV screen is 81.28 cm. A US men's size 10 shoe has an insole of approximately 28 cm. A standard A4 paper sheet is 29.7 Ã 21 cm, equivalent to 11.69 Ã 8.27 inches.
For height: 6 feet is 182.88 cm. 170 cm is 5 feet 7 inches. The converter above handles height conversion automatically â enter feet and get centimeters, or enter centimeters and get feet and inches.
Kilometers to Miles for Road Distances
The fastest mental math approximation: multiply kilometers by 0.6 to get miles, or multiply miles by 1.6 to get kilometers. This is slightly off (the real factor is 0.621) but accurate enough for most driving estimates. A 100 km trip is about 62 miles. A 26.2-mile marathon is 42.2 km.
Frequently Asked Questions
What is the exact conversion between inches and centimeters?
By international agreement since 1959, 1 inch = 2.54 centimeters exactly. This is a defined value, not an approximation. From this: 1 foot = 30.48 cm, 1 yard = 91.44 cm, 1 mile = 1,609.344 m exactly.
How do I convert height from feet/inches to centimeters?
Convert feet to inches first (multiply by 12), add the remaining inches, then multiply total inches by 2.54. Example: 5 feet 9 inches = (5Ã12)+9 = 69 inches à 2.54 = 175.26 cm. The converter above handles this automatically.
What's the difference between a nautical mile and a regular mile?
A nautical mile is 1,852 meters (1.852 km), compared to a statute mile of 1,609.344 meters. Nautical miles are used in aviation and maritime navigation because one nautical mile corresponds to one arc-minute of latitude on Earth's surface, making navigation calculations simpler.
How accurate are the conversions on this tool?
All conversions use precise factors (not rounded approximations) internally. The displayed result is rounded to 6 decimal places where applicable. For scientific or engineering purposes, verify against official standards if extreme precision is required.