Converting Millimeters to Fractional Inches

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<h3>Converting Millimeters to Fractional Inches</h3>

Converting millimeters (mm) to fractional inches is a matter of rounding to the nearest 16th of an inch, since this is how far inches are broken down on rulers. The conversion factor between inches and mm is 25.4.

Step 1

Measure or identify the length in mm for the object of interest.



Step 2

Divide the amount in Step 1 by 25.4 to get the inches in decimal form.

Step 3

Take the decimal portion of the result of Step 2 and multiply it by 16. The point is to determine the nearest 16th of an inch on a ruler.

For example, 120 mm divided by 25.4 yields 4.7244 inches. Multiplying the 0.7244 by 16 gives 11.591. Round this to 12/16, or 3/4. The result, therefore, is 4 3/4 inches.

TL;DR (Too Long; Didn’t Read)

If you’re making the conversion from mm to fractional inches for tools, you’ll probably want to use 32 instead of 16. Following the exact same calculations but using 32 instead of 16, the answer for the example would become 4 23/32 inches. Wire width conversion could entail converting to the nearest 64th of an inch.



Dave Pennells

By Dave Pennells

Dave Pennells, MS, has contributed his expertise as a career consultant and training specialist across various fields for over 15 years. At City University of Seattle, he offers personal career counseling and conducts workshops focused on practical job search techniques, resume creation, and interview skills. With a Master of Science in Counseling, Pennells specializes in career consulting, conducting career assessments, guiding career transitions, and providing outplacement services. Her professional experience spans multiple sectors, including banking, retail, airlines, non-profit organizations, and the aerospace industry. Additionally, since 2001, he has been actively involved with the Career Development Association of Australia.