Square Centimeter to Square Inch Conversion Calculator: Free Online Tool

Convert square centimeters to square inches with our free online area converter.

From:

Square Centimeter

To:

Square Inch

How to Use the Calculator:

Enter the value you want to convert in the 'From' field (Square Centimeter).
The converted value in Square Inch will appear automatically in the 'To' field.
Use the dropdown menus to select different units within the Area category.
Click the swap button (⇌) to reverse the conversion direction.

How to Convert Square Centimeter to Square Inch

Converting Square Centimeter to Square Inch involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

1 Square Centimeter = 0.155 square inches

Example Calculation:

Convert 10 square centimeters: 10 × 0.155 = 1.550003 square inches

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

What is a Square Centimeter and a Square Inch?

The square centimeter (symbol: cm² or sometimes sq cm) is a unit of area in the International System of Units (SI). It represents the area of a square whose sides measure exactly one centimeter in length.

One square centimeter is equal to:

1/10,000 of a square meter (m²)
100 square millimeters (mm²)
Approximately 0.155 square inches (in²)

It is a derived SI unit, formed by squaring the SI base unit of length, the meter (via the centimeter).

The Square Inch (symbol: in² or sq in) is a unit of area in both the British Imperial and United States customary systems of measurement. It is defined as the area of a square whose sides each measure exactly one inch in length.

Mathematically: 1 in² = 1 inch × 1 inch

It is related to other imperial/US customary area units:

1 square foot (ft²) = 144 in² (since 1 ft = 12 in)
1 square yard (yd²) = 1,296 in² (since 1 yd = 3 ft = 36 in)

In terms of metric units, based on the international inch defined as exactly 25.4 millimeters (mm):

1 in² = (25.4 mm)² = 645.16 mm²
1 in² = (2.54 cm)² = 6.4516 cm²
1 in² = (0.0254 m)² = 0.00064516 m²

Note: The Square Centimeter is part of the metric (SI) system, primarily used globally in science and trade. The Square Inch belongs to the imperial/US customary system.

History of the Square Centimeter and Square Inch

Metric System Origins: The concept of the square centimeter naturally arose with the establishment of the metric system during the late 18th century in France. As the centimeter (one-hundredth of a meter) was defined as a convenient subunit of length, the square centimeter became the corresponding unit for small areas.
SI Adoption: With the formalization of the International System of Units (SI) in the mid-20th century, the square meter (m²) was established as the coherent derived unit for area. The square centimeter (cm²), as a direct subdivision (1 cm² = 10⁻⁴ m²), is an accepted SI unit commonly used for measuring smaller areas where the square meter would be impractically large.

Origin: The square inch originates from the inch, a fundamental unit of length in the English (later British Imperial and US customary) systems. The concept of measuring area based on squaring a length unit dates back to ancient measurement practices.
Evolution of the Inch: The precise length of the inch itself varied significantly over centuries and by location before the 20th century. Early definitions were often based on barleycorns or thumb widths.
Standardization (International Inch): In 1959, the United States and countries of the Commonwealth of Nations agreed upon the definition of the international yard as exactly 0.9144 meters. This agreement consequently defined the international inch as exactly 25.4 millimeters (mm). This standardization fixed the exact metric equivalent of the square inch as 6.4516 square centimeters (cm²).
Continued Use: Despite widespread global metrication, the square inch remains a common unit in the United States, and to a lesser extent in the United Kingdom and Canada, particularly in certain trades and industries.

Common Uses for square centimeters and square inches

Explore the typical applications for both Square Centimeter (metric) and Square Inch (imperial/US) to understand their common contexts.

Common Uses for square centimeters

The square centimeter is frequently used for measuring relatively small surface areas across various fields:

Science: Measuring the surface area of small biological samples (like leaves or petri dishes), cross-sectional areas in physics and materials science, and quantifying reaction surfaces in chemistry.
Medical Imaging: Commonly used to report the area of skin lesions, wounds, organ cross-sections, or regions of interest in MRI, CT, or ultrasound scans.
Education: A fundamental unit in teaching geometry, area calculation, and understanding metric conversions in schools.
Manufacturing & Design: Specifying the area of small components, electronic parts (like integrated circuits), adhesive patches, or surface coating requirements.
Photography: Sometimes used informally to refer to the approximate size of smaller image sensors.
Retail & Labeling: Used on packaging to indicate the size of small items like stickers, patches, or fabric samples.

Common Uses for square inches

The square inch is primarily used for measuring relatively small areas, especially in specific fields:

Engineering and Manufacturing (US/UK): Specifying the cross-sectional area of wires, beams, or pipes; surface area of small mechanical parts; material stress calculations (often in conjunction with psi - pounds per square inch).
Electronics: Measuring the surface area of components like microchips or circuit boards.
Material Science: Quantifying the area of material samples for testing (e.g., fabric swatches, paper sheets).
Printing and Graphic Design (US): Sometimes used for small image dimensions or layout areas, although points and picas are also common.
Pressure Measurement: Implicitly used as the denominator in the widely used unit of pressure, pounds per square inch (psi).
Retail (Specific Goods): Occasionally used for pricing small, specialized items sold by area (e.g., certain textiles, craft supplies).
Crafts and Hobbies: Measuring small patches of fabric, paper dimensions, or design elements in quilting, scrapbooking, etc.

It is generally too small for measuring room dimensions (square feet are used) or land (acres or square miles are used).

Frequently Asked Questions

Questions About Square Centimeter (cm²)

How small is a square centimeter visually?

One square centimeter is the area of a square 1 cm by 1 cm. This is roughly:

The size of the nail on an adult human index finger.
Slightly smaller than a standard US postage stamp.
About the size of one face of a standard six-sided die.

How many square millimeters (mm²) are in a square centimeter (cm²)?

There are exactly 100 square millimeters (mm²) in one square centimeter (cm²). This is because 1 cm = 10 mm, so 1 cm² = (10 mm) × (10 mm) = 100 mm².

How many square centimeters (cm²) are in a square meter (m²)?

There are exactly 10,000 square centimeters (cm²) in one square meter (m²). This is because 1 m = 100 cm, so 1 m² = (100 cm) × (100 cm) = 10,000 cm².

How do you convert square centimeters (cm²) to square inches (in²)?

To convert square centimeters to square inches, multiply the value in cm² by approximately 0.155. For example, 10 cm² is roughly 1.55 in². Conversely, 1 square inch is approximately 6.4516 square centimeters.

Is the square centimeter (cm²) an SI unit?

Yes, the square centimeter (cm²) is a derived unit of area within the International System of Units (SI). While the coherent SI unit for area is the square meter (m²), the cm² (equal to 10⁻⁴ m²) is formed using an accepted SI prefix (centi-) and is widely used for convenience when measuring smaller areas.

When is cm² used instead of m²?

Square centimeters (cm²) are preferred when measuring areas significantly smaller than one square meter, where using m² would result in very small decimal numbers (e.g., 0.005 m²). It offers a more convenient scale for objects like small electronic components, biological samples, or details in medical images.

About Square Inch (in²)

How many square inches are in one square foot?

There are exactly 144 square inches in one square foot. This is because 1 square foot is the area of a square with 12-inch sides (12 inches × 12 inches = 144 in²).

How do you convert square inches to square centimeters?

To convert square inches to square centimeters, multiply the area in square inches by 6.4516.

Conversion formula: Area [cm²] = Area [in²] × 6.4516
Example: 10 in² = 10 × 6.4516 cm² = 64.516 cm²

Is the square inch the same as "inches squared"?

Yes, the terms "square inch" (in²) and "inches squared" refer to the same unit of area.

Is the square inch an SI unit?

No, the square inch is not part of the International System of Units (SI). It belongs to the British Imperial and US customary systems. The corresponding SI units for area are the square meter (m²) and its derived units like the square centimeter (cm²) and square millimeter (mm²).

Why is psi (pounds per square inch) so common?

Pounds per square inch (psi) became a standard unit for measuring pressure (force per unit area) in many English-speaking countries, particularly in engineering and industrial applications, due to the established use of the pound for force and the inch for dimensions within the Imperial and US customary systems. While the SI unit for pressure is the Pascal (Pa), psi remains deeply ingrained in many technical fields in the US.

Conversion Table: Square Centimeter to Square Inch

Square Centimeter (cm²)	Square Inch (in²)
1	0.155
5	0.775
10	1.55
25	3.875
50	7.75
100	15.5
500	77.5
1,000	155

All Area Conversions

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