What size is a Number 4 drill bit? (#4 drill bit size)

What size is a #4 drill bit?

Numbered drill bit gauge sizes range in ascending order from 80 (smallest) to 1 (largest). Thus, drill bit #4 is on the larger side of your standard drill set. Here we will give you drill bit #4 in decimal inches, drill bit #4 in fractional inches, and drill bit #4 in decimal millimeters (mm).

The purpose of this page is to give you an alternate drill bit (approximate equivalent) to drill bit gauge size Number 4 (#4).

We start by displaying drill bit Number 4 in decimal inches as follows:

#4 drill bit = 0.2090 inches

0.2090 decimal as a fraction is 209/1000. However, standard fractional drill bits come in intervals of 1/64 inches. Therefore, there are no standard fractional drill bits that are the exact 209/1000 fraction that the #4 drill bit is. To find the closest gauge wire #4 drill bit equivalent in fractional inches, we round 209/1000 up and down to 1/64 accuracy to get the following:

≈ 13/64 inches rounded down
#4 drill bit = 209/1000 inches
≈ 7/32 inches rounded up

Caution: Due to rounding, a 13/64 drill bit will make the hole smaller than a #4 drill bit and a 7/32 drill bit will make the hole larger than a #4 drill bit. Below we converted the fractions to decimals so you can compare more easily:

13/64 = 0.203125 inches
#4 = 0.2090 inches
7/32 = 0.21875 inches

There are 25.4 millimeters (mm) in an inch. Thus, to convert a #4 drill bit to millimeters, you simply multiply the decimal inches by 25.4 like so:

0.2090 inches x 25.4
= 5.3086 mm

Drill Bit Size Chart
For additional information about what drill bit to use, you may also want to take a look at the Drill Bit Size Chart which includes fractional inch drill bits, gauge wire drill bits, and metric drill bits sorted by size.

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