25/64 Inch to MM
Fractional inch to millimeters
25/64 inch (25/64β³)
9.921875 mm
= 0.992188 cm Β· 0.390625 inch decimal Β· 1 inch = 25.4 mm exactly
π‘ Standard fractional drill bit size. 1/64 in is also the finest graduation printed on a US tape measure.
Also written as
25/64 to mm Β· 25/64 in mm Β· 25/64" in mm Β· 25/64 inch in mm Β· 25/64 inches to millimeters Β· 25/64 en mm Β· 0.390625 inch to mm
All of these mean the same measurement. The double-prime mark (β³) and the plain quote (") both stand for inches, and en mm is simply the French and Spanish wording of the same question.
Closest metric drill size
10 mm
25/64β³ = 9.921875 mm Β· difference 0.0781 mm
Metric drills step in 0.5 mm, so a fractional inch size rarely lands exactly on one. A 0.0781 mm gap is usually invisible in a clearance hole but changes the fit on a press fit or a tapped hole.
Nearby fractional inches
| Fraction | mm | cm | Decimal |
|---|---|---|---|
| 23/64β³ | 9.128125 mm | 0.912813 cm | 0.359375β³ |
| 3/8β³ | 9.525 mm | 0.9525 cm | 0.375β³ |
| 25/64β³ | 9.921875 mm | 0.992188 cm | 0.390625β³ |
| 13/32β³ | 10.31875 mm | 1.031875 cm | 0.40625β³ |
| 27/64β³ | 10.715625 mm | 1.071562 cm | 0.421875β³ |
25/64β³ is 25/64 of an inch β the 25th mark from zero on a tape measure graduated in sixty-fourths.
FAQ
How many mm is 25/64 inch?
25/64 inch equals 9.921875 mm. One inch is defined as exactly 25.4 mm, so the result is 25.4 Γ 25 Γ· 64.
What is 25/64 inch in decimal?
25/64 inch is 0.390625 inch in decimal, which is 9.921875 mm or 0.992188 cm.
Which metric size is closest to 25/64 inch?
10 mm is the closest common metric size, a difference of 0.0781 mm. Fractional-inch and metric fasteners are not interchangeable when the gap is more than about 0.2 mm.
Why is the value exact?
The international yard and pound agreement of 1959 fixed the inch at exactly 25.4 mm, so fractional inch conversions terminate rather than repeat.
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