5/64 Inch to MM

Fractional inch to millimeters

5/64 inch (5/64β€³)
1.984375 mm
= 0.198437 cm Β· 0.078125 inch decimal Β· 1 inch = 25.4 mm exactly
πŸ’‘ Standard fractional drill bit size. 1/64 in is also the finest graduation printed on a US tape measure.
Also written as

5/64 to mm Β· 5/64 in mm Β· 5/64" in mm Β· 5/64 inch in mm Β· 5/64 inches to millimeters Β· 5/64 en mm Β· 0.078125 inch to mm

All of these mean the same measurement. The double-prime mark (β€³) 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
2 mm
5/64β€³ = 1.984375 mm Β· difference 0.0156 mm
Metric drills step in 0.5 mm, so a fractional inch size rarely lands exactly on one. A 0.0156 mm gap is usually invisible in a clearance hole but changes the fit on a press fit or a tapped hole.
Nearby fractional inches
FractionmmcmDecimal
3/64β€³1.190625 mm0.119063 cm0.046875β€³
1/16β€³1.5875 mm0.15875 cm0.0625β€³
5/64β€³1.984375 mm0.198437 cm0.078125β€³
3/32β€³2.38125 mm0.238125 cm0.09375β€³
7/64β€³2.778125 mm0.277813 cm0.109375β€³
5/64β€³ is 5/64 of an inch β€” the 5th mark from zero on a tape measure graduated in sixty-fourths.
FAQ
How many mm is 5/64 inch?
5/64 inch equals 1.984375 mm. One inch is defined as exactly 25.4 mm, so the result is 25.4 Γ— 5 Γ· 64.
What is 5/64 inch in decimal?
5/64 inch is 0.078125 inch in decimal, which is 1.984375 mm or 0.198437 cm.
Which metric size is closest to 5/64 inch?
2 mm is the closest common metric size, a difference of 0.0156 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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5/64 inch to mm

5/64 inch is 25.4 Γ— 5 Γ· 64 = 1.984375 mm, or 0.198437 cm. In decimal inches it is 0.078125β€³. Because the inch is defined as exactly 25.4 millimeters, fractional inch values convert without rounding.

Where this size shows up

Standard fractional drill bit size. 1/64 in is also the finest graduation printed on a US tape measure.

Matching it to metric

The nearest metric drill size is 2 mm, a difference of 0.0156 mm. Whether that matters depends on the job: a clearance hole tolerates it, a press fit or a tapped hole does not. For hex fasteners the same logic applies to socket sizes β€” a socket even a few tenths oversize will round the corners of the head.

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