Having the right drill bits on hand is critical, whether you’re a weekend warrior, or a professional carpenter or contractor. Considering the sheer volume of different bits on the market, this is easier said than done, and it gets even more complicated once you realize that not all measurements correspond to standard bit sizes.
Today, we’ll cover a drill bit size chart, so you can ensure you always have the right tool for the job.
How Many Drill Bits are There?
Maybe a better question would be how much time you have!
All kidding aside, when it comes to drill bits, there’s a seemingly endless array of different sizes. Of course, some bits have specialized applications and aren’t relevant for most basic work around the house.
A typical set of drill bits includes somewhere between 12 and 30 bits. As a rule of thumb, any set that contains 20 or more bits should be more than enough for most craftsmen.
Here are the most common sizes for a standard (fractional) bit set:
| 1/16 | 5/32 | 1/4 | 11/32 | 7/16 |
| 5/64 | 11/64 | 17/64 | 23/64 | 29/64 |
| 3/32 | 3/16 | 9/32 | 3/8 | 15/32 |
| 7/64 | 13/64 | 19/64 | 25/64 | 31/64 |
| 1/8 | 7/32 | 5/16 | 13/32 | 1/2 |
| 9/64 | 15/64 | 21/64 | 27/64 |
Keep in mind that there are hundreds of more bits beyond the ones that we’ve covered here. However, if you have bits in these sizes, you’re well on your way to having every drill bit you’ll ever need.
Matching Bits to Screws
For new construction, it’s essential to know which drill bit corresponds to which screw size. Most standard screws are sized by number, from 1-12, and each of those numbers corresponds to a different drill bit size.
| Screw Size | Bit Size |
| #1 | 5/64 |
| #2 | 3/32 |
| #3 | 7/64 |
| #4 | 1/8 |
| #5 | 1/8 |
| #6 | 9/64 |
| #7 | 5/32 |
| #8 | 11/64 |
| #9 | 11/64 |
| #10 | 3/16 |
| #11 | 3/16 |
| #12 | 7/32 |
The Issue with Standard Drill Bits
So far, everything has been relatively straightforward and easy to understand. However, there’s a curveball coming. Just because your drill bits are sized in fractions doesn’t mean the rest of the world is. You’re regularly going to encounter fasteners or hole sizes that are sized metrically, usually in millimeters.
So, what do you do when you need to make conversions from standard to metric? There are two different ways to tackle this issue. If you’re a regular Einstein, you can do the math yourself. Or, if you prefer to avoid doing math altogether, a pocket bit gauge is worth its weight in gold.
Doing the Conversions Yourself
If you’re interested in doing bit conversions yourself, all you’ll need is a calculator and these formulas:
- For conversions from millimeters to inches: multiply the number by .039
- For conversions from inches to millimeters: multiply the number by 25.4
Using a Bit Chart
Sure, you could sit there doing the math anytime you need to make a conversion. Or, you could save yourself time by referring to a bit gauge when it’s time to convert. These handy gauges are worth their weight in gold, and most of them will fit in your pocket or wallet.
Bit gauges are made from either plastic or metal and feature a series of holes that correspond to different bit sizes, along with their standard size, and metric conversions.
Best Drill Bit Size Charts
Rather than send you to the store armed with nothing but the cash in your pocket, we’ve taken a look at tons of different size charts and bit gauges for you to choose from. Each of these gauges will provide you everything you need to do conversions on the spot.
Morse Plastic Wall Chart
This chart is a must for any shop, as it has literally everything you could ever need to know, in one convenient place. This chart provides conversions for standard bits to their decimal conversions, numbered bits to their decimal conversions, and metric bits to their decimal conversions.
There’s also recommended tap sizes for unified and metric threads, recommended diameters for pipe taps, and a handy list of formulas for doing your own conversions.
Pros
- Heavy duty construction
- Includes practically every conversion you’ll ever need
- Perfect for hanging on the shop wall
Cons
- Not portable
- Doesn’t include a bit gauge
Irwin Steel Drill Gauge
Irwin is one of the most reputable manufacturers of cutting tools, and their solid steel bit gauge is built to last forever. This compact gauge is perfect for stashing in your pocket or your toolbox, and it includes conversions for 29 standard size bits from 1/16-½.”
The gauge is black, and the stamped markings are all etched in white, so it’s easy to see all of the markings, even in low lighting.
Pros
- Easy to read
- Will last forever
- Includes a bit gauge
Cons
- Doesn’t include conversions for non-standard bits
Woodstock 3-Piece Bit Gauge
This bit gauge from Woodstock includes three different gauges, so you’re covered whether you’re using standard, numbered, or lettered bits. This comprehensive kit is perfect for anyone who regularly works with bits or holes outside of the standard kit.
Made from solid steel, this bit gauge set will stand up to the test of time, and it should be the last set you ever need. However, there’s no contrast between the steel itself and the stamped markings, so they’re difficult to read at a distance.
Pros
- Solid steel construction
- 3-piece set includes every conversion you’ll ever need
Cons
- Difficult to read
- Not as tightly toleranced as other sets
Final Word
Having the right bit for the job is critical, and it’s one of the factors that separates seasoned professionals from the chumps who are just trying their best. But, with so many bits and conversions to account for, ensuring you have the right bit for the job can get tricky.
Thankfully, drill bit size charts and gauges can take all the guesswork out of a job, ensuring that you’re always pairing the right tool to the task.
