How to use this inches converter
Enter the inch measurement, confirm Inches in the From menu, and choose the required destination unit. The result updates immediately. You can switch either menu for a reverse calculation, such as centimeters to inches, without opening another page or manually inverting a rounded factor.
How the calculation works
One international inch is defined as exactly 2.54 centimeters, which is also exactly 25.4 millimeters. This definition links customary length measurements to the SI meter and is more reliable than a shortened mental estimate such as 2.5 centimeters per inch.
Twelve inches make one foot and 36 inches make one yard. For mixed feet-and-inches notation, convert the feet portion to inches first, add the remaining inches, and then convert the total. For example, 5 feet 8 inches becomes 5 × 12 + 8 = 68 inches.
Conversion changes the unit, not the quality of the measurement. Manufacturing tolerances, ruler markings, screen dimensions, and nominal product sizes can all limit accuracy even when the arithmetic factor is exact.
Formulas
Inches to centimeters
Inches to millimeters
Inches to feet
Worked examples
Convert 10 inches to centimeters
10 × 2.54 = exactly 25.4 centimeters.
Convert 68 inches to feet
68 ÷ 12 = 5.666666…, equivalent to 5 feet 8 inches when expressed in mixed notation.
Convert 0.5 inch to millimeters
0.5 × 25.4 = exactly 12.7 millimeters.
Common uses
Product and component dimensions
Convert displays, hardware, furniture, paper, and small components between inches and metric units. Check whether a product dimension is nominal, diagonal, or measured along a particular axis.
Crafts and household projects
Translate ruler and pattern measurements when instructions and tools use different systems. Preserve fractional-inch tolerances rather than rounding early to a convenient metric value.
Technical comparison
Compare an inch-based specification with millimeter or centimeter documentation using the exact 25.4-millimeter relationship.
Accuracy and limitations
The inch-to-centimeter and inch-to-millimeter relationships are exact. The result display may round a nonterminating reverse conversion for readability.
Manufacturing tolerances, screen bezels, fabric stretch, tool accuracy, and nominal sizes are separate from the mathematical conversion and must be evaluated from the source specification.
Frequently asked questions
How many centimeters are in an inch?
One international inch equals exactly 2.54 centimeters.
How many millimeters are in an inch?
One inch equals exactly 25.4 millimeters.
How do I convert feet and inches together?
Multiply the feet by 12, add the remaining inches, and convert that total inch value.
Are screen inches an area measurement?
No. A screen size in inches normally describes a diagonal length, not its width, height, or area.
Why can the result contain many decimals?
Some unit ratios do not terminate cleanly in decimal notation. Round only to the precision appropriate for the source measurement.
Is this converter free and private?
Yes. It is free to use, requires no account, and performs the calculation in your browser.