What size is a Number 15 drill bit? (#15 drill bit size)

What size is a #15 drill bit?

Numbered drill bit gauge sizes range in ascending order from 80 (smallest) to 1 (largest). Thus, drill bit #15 is on the larger side of your standard drill set. Here we will give you drill bit #15 in decimal inches, drill bit #15 in fractional inches, and drill bit #15 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 15 (#15).

We start by displaying drill bit Number 15 in decimal inches as follows:

#15 drill bit = 0.1800 inches

0.1800 decimal as a fraction is 9/50. However, standard fractional drill bits come in intervals of 1/64 inches. Therefore, there are no standard fractional drill bits that are the exact 9/50 fraction that the #15 drill bit is. To find the closest gauge wire #15 drill bit equivalent in fractional inches, we round 9/50 up and down to 1/64 accuracy to get the following:

≈ 11/64 inches rounded down
#15 drill bit = 9/50 inches
≈ 3/16 inches rounded up

Caution: Due to rounding, a 11/64 drill bit will make the hole smaller than a #15 drill bit and a 3/16 drill bit will make the hole larger than a #15 drill bit. Below we converted the fractions to decimals so you can compare more easily:

11/64 = 0.171875 inches
#15 = 0.1800 inches
3/16 = 0.1875 inches

There are 25.4 millimeters (mm) in an inch. Thus, to convert a #15 drill bit to millimeters, you simply multiply the decimal inches by 25.4 like so:

0.1800 inches x 25.4
= 4.5720 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.

Gauge Number Drill Bit Size
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