Inches to CM Converter (All Length Units)

Inches to Centimeters – Exact 2.54 Factor Guide

Core idea: The inch is legally defined so that 1 in = 2.54 cm exactly. Every inch value multiplies cleanly by 2.54; reverse by dividing. No approximation required.

Formulas

• cm = in × 2.54
• in = cm ÷ 2.54
• Fractions: a/b in = (a ÷ b) × 2.54 cm
• Millimeters link: mm = in × 25.4

Quick Values

Worked Example

Example: 7.5 in → cm = 7.5 × 2.54 = 19.05 cm. Reverse: 19.05 ÷ 2.54 = 7.5 in (confirms).

Where Used

• Mechanical drawings & woodworking (fractional inches → metric hardware).
• Display sizes (monitors, phones) vs. international spec sheets (cm/mm).
• Sewing & crafts bridging imperial patterns to metric fabric dimensions.

Accuracy & Tips

• 2.54 is exact—avoid using 2.5 (≈2% short).
• Fractions: convert to decimal first (e.g., 5/8 = 0.625) then × 2.54.
• For mm fast: inches × 25 = slight low; add 0.4% (≈ +0.01 per inch).

More Examples

FAQ

• Is 1 inch really exactly 2.54 cm? Yes—defined by international agreement (1959).
• Why do some charts show 0.3937? That’s the reciprocal (1 cm in inches).
• Best precision? For everyday: 2 decimals cm. Engineering: carry 2.54 fully.

Exact factor 2.54 used; rounding only in presented tables.