To convert centimeters to inches yourself, use the standard conversion factor where 1 inch equals exactly 2.54 cm:

Inches=30.52.54≈12.00787Inches equals 30.5 over 2.54 end-fraction is approximately equal to 12.00787 Common Uses

Inches=Centimeters2.54Inches equals the fraction with numerator Centimeters and denominator 2.54 end-fraction

Many standard "12-inch" frames are sized at 30.5 cm to ensure a proper fit for international metric-standard prints.

Standard watercolor paper and canvases often come in inch sizes, which translate to roughly