Convert Square Centimeters to Square Inches

Formula

in² = cm² × 0.1550003100006

or in² = cm² ÷ 6.4516

Derivation from SI units:

• 1 cm² = (0.01 m)² = 10⁻⁴ m²
• 1 in² = (0.0254 m)² = 6.4516 × 10⁻⁴ m² = 6.4516 cm²
• 1 cm² = 0.0001 m² ÷ 0.00064516 m² per in² = 0.1550003100006 in²

Both units are defined exactly, so the factor is exact. Square Centimeter definition: square centimeter; Square Inch definition: square inch.

Worked examples

1. The ASTM D737 test area of 38.3 cm² is 5.936511873 in².
   38.3 cm² × 0.15500031 = 5.936511873 in²
2. The ISO 9237 test area of 20 cm² is 3.1000062 in².
   20 cm² × 0.15500031 = 3.1000062 in²

Where it's used

Test areas, gasket and sample sizes in cm² are converted to in² when US methods, fixtures or customers are involved.

Square Centimeter to other area units

Frequently asked questions

Sources

• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 2 with SI prefix centi.
• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "square inch (in²)".

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.