1 Inches to Millimeters
1 inch is equal to 25.4 millimeters.
How to Convert 1 Inches to Millimeters
To convert 1 inch to millimeters, multiply 1 by 25.4:
Reversing the calculation: 25.4 millimeters ÷ 25.4 = 1 inches.
What Does 1 Inches Look Like?
1 inch (25.4 millimeters) is about the size of a coin. Measurements in inches are deeply embedded in US construction, where lumber, drywall, plumbing, and tile work are all cut and laid out at inch precision.
In photography, lens filters, sensor sizes, and tripod thread standards still use inches as the historical default.
For additional reference, 1 in also equals approximately 25.4 mm or 0.083 ft. Looking at the result side: In machining and CNC work, millimeters describe drill bit sizes, end mill diameters, and feature dimensions on production drawings.
Nearby Values — Inches to Millimeters
FAQ
How many millimeters is 1 inch?
1 inch = 25.4 millimeters.
How do I convert inches to millimeters?
Multiply the number of inches by 25.4. Formula: mm = in × 25.4.
Is 1 in = 25.4 mm exact?
Yes — the conversion factor (25.4) is exact by international definition, so 1 in converts to 25.4 mm without any rounding error.
What is half and double of 1 inches in millimeters?
Half of 1 inches is 0.5 in = 12.7 mm. Double is 2 in = 50.8 mm.
How do I convert 25.4 millimeters back to inches?
Divide 25.4 by 25.4, or equivalently multiply by 0.0393701. The reverse calculation returns 1 inches, confirming the original input.