Tapping Drill Size Chart & Clearance Holes.
Welcome to our tapping sizes and clearance holes chart, essential for everyone in the field of precision engineering needing to tap holes for metric and imperial threads or provide a through hole for a fastener.
This handy tap drill size chart is designed to provide you with detailed, practical information to ensure the accuracy and effectiveness of your threaded assemblies.
Here, you’ll find an extensive database of standard tapping drill sizes, alongside their corresponding clearance holes for metric and imperial units, tailored to facilitate the selection and use of screws and bolts in various applications.
Whether you're drafting a project, in the midst of procurement, or performing hands-on assembly, this guide aims to support your engineering needs with clarity and precision.
Tip From Our Engineers
“While accurate, these drill and tap sizes are given in their closest measurement in millimetres (mm). They should be taken as a recommendation. We advise you to test tapping and threading on a waste piece of material before committing these measurements to a threaded hole in your workpiece.”
Patrick Faulkner
Lead Engineer
Metric Tap Drill Sizes
Tapping drill sizes for metric threads involves knowing if you need standard/coarse threads, which are usually the go-to, or fine threads, which are usually more prevalent in precise projects. Once you know the thread size, you can find the tap hole size needed below.
| Thread Size |
Standard/Coarse Tap Drill Diameter |
Fine Tap Drill Diameter (mm) |
Clearance Hole Drill Diameter (mm) |
|---|---|---|---|
| M1 | 0.75 | 0.80 | 1.3 |
| M1.1 | 0.85 |
0.90 |
1.4 |
| M1.2 | 0.95 | 1.00 | 1.5 |
| M1.4 | 1.10 | 1.20 | 1.8 |
| M1.6 | 1.25 | 1.40 | 2.0 |
| M1.8 | 1.45 | 1.60 | 2.3 |
| M2 | 1.60 | 1.75 | 2.6 |
| M2.2 | 1.75 | 1.95 | 2.9 |
| M2.5 | 2.05 | 2.15 | 3.1 |
| M3 | 2.50 | 2.65 | 3.6 |
| M3.5 | 2.90 | 3.15 | 4.2 |
| M4 | 3.30 | 3.50 | 4.8 |
| M4.5 | 3.80 | 4.00 | 5.3 |
| M5 | 4.20 | 4.50 | 5.8 |
| M6 | 5.00 | 5.25 | 7.0 |
| M7 | 6.00 | 6.25 | 8.0 |
| M8 | 6.80 | 7.00 | 10.0 |
| M9 | 7.80 | 8.00 | 11.0 |
| M10 | 8.50 | 8.80 | 12.0 |
| M11 | 9.50 | 10.00 | 13.5 |
| M12 | 10.20 | 10.50 | 15.0 |
| M14 | 12.00 | 12.50 | 17.0 |
| M16 | 14.00 | 14.50 | 19.0 |
| M18 | 15.50 | 16.00 | 22.0 |
| M20 | 17.50 | 18.00 | 24.0 |
| M22 | 19.50 | 20.00 | 26.0 |
| M24 | 21.00 | 22.00 | 28.0 |
| M27 | 24.00 | 25.00 | 33.0 |
| M30 | 26.50 | 28.00 | 35.0 |
| M33 | 29.50 | 31.00 | 38 |
| M36 | 32.00 | 33.00 | 41 |
| M39 | 35.00 | 36.00 | 44 |
| M42 | 37.50 | 38.00 | 47 |
| M45 | 40.50 | 41.00 | 50 |
| M48 | 43.00 | 44.00 | 53 |
| M52 | 47.00 | 48.00 | 57 |
| M56 | 50.50 | 52.00 | 61 |
| M60 | 54.50 | 56.00 | 65 |
| M64 | 58.00 | 60.00 | 69 |
| M68 | 62.00 | 64.00 | 73 |
Imperial Tap Drill Sizes
Tapping drill sizes for imperial threads requires identifying whether you need Unified National Coarse (UNC) threads, commonly used for general purposes, or Unified National Fine (UNF) threads, which are preferred for more precise engineering projects. After determining the specific thread size, you can find the corresponding tap hole size needed in the data provided below.
| Thread Size |
UNC Pitch (TPI) |
UNC Tap Drill Diameter |
UNF Pitch (TPI) |
UNF Tap Drill Diameter (decimal inch / mm) |
Clearance Hole Drill Diameter (mm) |
|---|---|---|---|---|---|
| #0 | - | - | 80 | 0.0468" / 1.19 | 0.07" / 1.78 |
| #1 - 64 | 64 | .0575" / 1.45 | 72 | 0.0595" / 1.51 | 0.081" / 2.06 |
| #2 - 56 | 56 | .0700" / 1.8 | 64 | 0.0700" / 1.78 | 0.096" / 2.44 |
| #3 - 48 | 48 | .0785" / 2 | 56 | 0.0820" / 2.08 | 0.11" / 2.79 |
| #4 - 40 | 40 | 0.089" /2.26 | 48 | 0.0935" / 2.37 | 0.1285" / 3.26 |
| #5 - 40 | 40 | 0.1015" / 2.58 | 44 | 0.1040" / 2.64 | 0.136" / 3.45 |
| #6 - 32 | 32 | 0.1065" / 2.7 | 40 | 0.1130" / 2.87 | 0.1495" / 3.80 |
| #8 - 32 | 32 | 0.136" / 3.45 | 36 | 0.1360" / 3.45 | 0.177" / 4.50 |
| #10 - 24 | 24 | 0.147" / 3.73 | 36 | 0.1590" / 4.04 | 0.201" / 5.11 |
| #12 - 24 | 24 | 0.177" / 4.5 | 28 | 0.1820" / 4.62 | 0.228" / 5.79 |
| 1/4" - 20 | 20 | 0.2010" /5.1 | 28 | 0.2130" / 5.41 | 0.257" / 6.53 |
| 5/16" - 18 | 18 | 0.2570" / 6.53 | 24 | 0.2720" / 6.91 | 0.266" / 6.76 |
| 3/8" - 16 | 16 | 0.3125" / 7.94 | 24 | 0.3320" / 8.43 | 0.322" / 8.18 |
| 7/16" - 14 | 14 | 0.368" / 9.35 | 20 | 0.3906" / 9.92 | 0.397" / 10.08 |
| 1/2" - 13 | 13 | 0.4219" / 10.72 | 20 | 0.4531" / 11.51 | 0.5312" / 13.49 |
| 9/16" - 12 | 12 | 0.4844" / 12.3 | 18 | 0.5156" / 13.1 | 0.5938" / 15.08 |
| 5/8" - 11 | 11 | 0.5312" / 13.49 | 18 | 0.5781" /14.68 | 0.6562" / 16.67 |
| 3/4" - 10 | 10 | 0.6562" / 16.67 | 16 | 0.6875" / 17.46 | 0.7812" / 19.84 |
| 7/8" - 9 | 9 | 0.7656" / 19.45 | 14 | 0.8125" / 20.64 | 0.9062" / 23.02 |
| 1" - 8 | 8 | 0.8750" / 22.23 | 12 | 0.9375" / 23.81 | 1.0313" / 26.20 |
FAQs
Q: What size drill bit do I need to tap?
A: To determine the correct drill bit size for tapping and threading, identify the thread size you intend to tap and then refer to the drill for tap chart above that matches the thread and tap to the drill size. This ensures the tapped hole will accommodate the thread properly.
Q: How do I choose a drill tap?
A: Choosing the right drill tap involves knowing the size (metric or imperial) and type of thread required (coarse or fine). Select a tap that corresponds to the desired thread size, paying close attention to the material the type of tap is rated for, ensuring it can handle the job without breaking.
Q: How do I know what size tap I have?
A: To identify a tap size, examine the markings on the tap's shank, which typically indicate the thread type and size. If the markings are worn off, you can measure the tap’s outer major diameter at the thread peaks and compare it with a thread size chart.
Q: How do I know what size drill I have?
A: You can determine the size of a drill bit by measuring its diameter with a caliper or referring to any visible markings on the bit itself.