CM to Inches Converter
Instantly convert between centimeters, inches, and other length measurements
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1 centimeter = 0.393701 inches (exact)
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CM to Inches Conversion Reference
Conversion Formula
To convert centimeters to inches, multiply the length value by 0.393701.
Reverse Conversion
To convert inches to centimeters, multiply the length value by 2.54.
Quick Reference Guide
Comprehensive CM to Inches Conversion Table
Use this handy reference table for quick CM to Inches conversions. Ideal for everyday measurements and projects.
| Centimeters (cm) | Inches (in) | Centimeters (cm) | Inches (in) |
|---|---|---|---|
| 1 cm | 0.3937 in | 26 cm | 10.2362 in |
| 2 cm | 0.7874 in | 27 cm | 10.6299 in |
| 3 cm | 1.1811 in | 28 cm | 11.0236 in |
| 4 cm | 1.5748 in | 29 cm | 11.4173 in |
| 5 cm | 1.9685 in | 30 cm | 11.8110 in |
| 6 cm | 2.3622 in | 40 cm | 15.7480 in |
| 7 cm | 2.7559 in | 50 cm | 19.6850 in |
| 8 cm | 3.1496 in | 60 cm | 23.6220 in |
| 9 cm | 3.5433 in | 70 cm | 27.5591 in |
| 10 cm | 3.9370 in | 80 cm | 31.4961 in |
| 11 cm | 4.3307 in | 90 cm | 35.4331 in |
| 12 cm | 4.7244 in | 100 cm | 39.3701 in |
| 13 cm | 5.1181 in | 150 cm | 59.0551 in |
| 14 cm | 5.5118 in | 200 cm | 78.7402 in |
| 15 cm | 5.9055 in | 250 cm | 98.4252 in |
Understanding CM to Inches Conversion
What are Centimeters?
The centimeter (cm) is a unit of length in the metric system. One centimeter equals one-hundredth of a meter (0.01m). It's a standard unit of measurement in most countries around the world, used for everyday measurements like height, width, and small distances.
The metric system, including centimeters, is designed to work on base-10, making conversions within the system (mm to cm to m) simply a matter of moving the decimal point.
What are Inches?
The inch (in or ″) is a unit of length in the imperial and United States customary systems of measurement. One inch equals exactly 2.54 centimeters by international agreement since 1959. Inches are primarily used in the United States, Canada, and the United Kingdom.
There are 12 inches in a foot and 36 inches in a yard. Unlike the metric system, the imperial system doesn't use a base-10 scale, making conversions more complex.
Practical Examples of CM to Inches Conversion
Example 1: Paper Size
Standard A4 paper measures 21.0 × 29.7 centimeters.
Width: 21.0 cm × 0.393701 = 8.27 inches
Height: 29.7 cm × 0.393701 = 11.69 inches
This explains why A4 paper is often described as approximately 8.3 × 11.7 inches.
Example 2: TV/Monitor Size
When a TV is advertised as 55 inches, this refers to the diagonal measurement.
55 inches × 2.54 = 139.7 centimeters
So a 55-inch TV has a diagonal measurement of approximately 140 cm.
Example 3: Height Conversion
Converting a height of 175 cm to feet and inches:
175 cm × 0.393701 = 68.9 inches
68.9 inches = 5 feet 8.9 inches
So a person who is 175 cm tall is approximately 5 feet 9 inches tall.
Real-world Applications
Construction & DIY
Many building materials and tools are measured in both metric and imperial units. In countries that use the metric system, blueprints and measurements are in centimeters or meters, but tools might still use inches. Understanding conversion is crucial when:
- Working with international blueprints
- Purchasing tools and materials from different countries
- Following DIY instructions from international sources
Consumer Products
Many consumer products use both measurement systems:
- Electronics: Screen sizes typically in inches (TVs, monitors, tablets)
- Furniture: Dimensions may be provided in both systems
- Clothing: Sizing can vary between regions (inch-based or cm-based)
- Automotive: Parts and specifications often use both systems
Education
Understanding both systems and conversion between them is important in:
- Science classes, where metric is standard but imperial may be referenced
- Mathematics, especially geometry and measurement problems
- Engineering, where both systems might be used depending on industry
- International exchange programs where students encounter different systems
Healthcare
Medical professionals often need to convert between systems for:
- Patient measurements (height, circumference, wound size)
- Medical devices from different countries
- Research and publication in international journals
- Medication dosing based on body measurements
Historical Background of Measurement Systems
Historical Facts About Centimeters and Inches
- The metric system, including centimeters, was developed during the French Revolution in the late 18th century, seeking to create a rational, universal system of measurement.
- The inch has ancient origins, with variations of this unit used by many civilizations. Historically, it was defined as the width of a man's thumb.
- In 1959, the international yard and pound agreement standardized the inch at exactly 2.54 centimeters, creating a precise relationship between the two units.
- The United States is one of only three countries (alongside Liberia and Myanmar) that hasn't officially adopted the metric system for everyday use, though it's used in science, medicine, and many industries.
- The prefix "centi-" in centimeter comes from Latin and means "one-hundredth," reflecting that a centimeter is 1/100 of a meter.
- The word "inch" derives from the Latin "uncia," which meant "one-twelfth" – originally one-twelfth of a Roman foot.
Frequently Asked Questions
The conversion factor isn't a round number because the inch and centimeter were developed in different measurement systems. The relationship between them became standardized in 1959 when an international agreement defined 1 inch as exactly 2.54 centimeters. When we flip this conversion to get centimeters to inches, we get 1/2.54, which equals approximately 0.393701.
Yes! For a quick mental calculation, you can use the approximation that 1 inch is about 2.5 cm (instead of the exact 2.54 cm). This means you can:
- Divide the number of centimeters by 2.5, or
- Multiply the number of centimeters by 0.4 (which is close to 0.393701)
For example, to convert 20 cm to inches: 20 ÷ 2.5 = 8 inches (actual: 7.87 inches)
This approximation works well for everyday estimates.
The use of different measurement systems is largely due to historical and cultural factors:
- Most countries adopted the metric system (which includes centimeters) during the 19th and 20th centuries due to its decimal-based simplicity and standardization.
- The United States, United Kingdom (partially), and a few other countries continue to use imperial measurements (including inches) due to historical tradition, infrastructure, and the costs associated with changing established standards.
- The UK officially uses the metric system but still commonly uses imperial units like inches and feet in everyday contexts.
Today, international trade and science have largely standardized around the metric system, while some regional and traditional practices maintain the use of imperial units.
Several industries maintain the use of inches even in predominantly metric countries:
- Electronics: Screen sizes for TVs, monitors, and devices are typically measured in inches worldwide.
- Plumbing: Pipe diameters and fittings often use inch-based measurements internationally.
- Construction: Lumber and building materials sometimes maintain inch-based dimensions due to international standards.
- Aviation: Altitude is still often measured in feet in international aviation.
- Bicycles: Wheel sizes are commonly specified in inches globally.
This calculator uses the exact conversion factor of 0.393701 inches per centimeter (derived from the precise definition of 1 inch = 2.54 centimeters). The results are mathematically accurate to multiple decimal places.
For most everyday purposes, results are displayed with up to 6 decimal places for small values, and fewer decimals for larger values, striking a balance between precision and readability. This level of precision is more than adequate for virtually all practical applications, from construction to scientific work.