21/64 Inch to MM
Fractional inch to millimeters
21/64 inch (21/64β³)
8.334375 mm
= 0.833437 cm Β· 0.328125 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
21/64 to mm Β· 21/64 in mm Β· 21/64" in mm Β· 21/64 inch in mm Β· 21/64 inches to millimeters Β· 21/64 en mm Β· 0.328125 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
8.5 mm
21/64β³ = 8.334375 mm Β· difference 0.1656 mm
Metric drills step in 0.5 mm, so a fractional inch size rarely lands exactly on one. A 0.1656 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 |
|---|---|---|---|
| 19/64β³ | 7.540625 mm | 0.754063 cm | 0.296875β³ |
| 5/16β³ | 7.9375 mm | 0.79375 cm | 0.3125β³ |
| 21/64β³ | 8.334375 mm | 0.833437 cm | 0.328125β³ |
| 11/32β³ | 8.73125 mm | 0.873125 cm | 0.34375β³ |
| 23/64β³ | 9.128125 mm | 0.912813 cm | 0.359375β³ |
21/64β³ is 21/64 of an inch β the 21st mark from zero on a tape measure graduated in sixty-fourths.
FAQ
How many mm is 21/64 inch?
21/64 inch equals 8.334375 mm. One inch is defined as exactly 25.4 mm, so the result is 25.4 Γ 21 Γ· 64.
What is 21/64 inch in decimal?
21/64 inch is 0.328125 inch in decimal, which is 8.334375 mm or 0.833437 cm.
Which metric size is closest to 21/64 inch?
8.5 mm is the closest common metric size, a difference of 0.1656 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.
Advertisement (AdSense)