While Drilling is the process of making holes in a material (wood, masonry, metal, etc.), Tapping is the process of creating threads inside those holes for inserting screws. In the previous guide, we saw Drill Sizes Chart for various standards. But if you want to properly insert screws in the holes, then you need a Tap Drill Chart. So, in this guide, let us take a quick look at different Tap Drill Charts based on different standards.
So What Is Drill And Tap?
The combination of Drills and Drill Bits allow you to make holes in wood, bricks, concrete, metal and other materials. If you want to insert screws or bolts into these holes, then you need proper threaded walls on the holes. This is where a ‘Tap’ comes into play.
It is a tool that can create screw threads in holes created by drills. The process of creating threads in drill holes is known as Tapping.
Tap Drill Chart
Just like other sizes, even Drill Taps Sizes are available in both metric and imperial. We will take a look at different tap drill charts based on the drill to tap sizes.
Number Size Tap Drill Chart
| Tap Size | Drill Size | Decimal Value (in) |
| 0 – 80 | 3/64” | 0.0469 |
| 1 – 64 | #53 | 0.0595 |
| 1 – 72 | #53 | 0.0595 |
| 2 – 56 | #50 | 0.07 |
| 2 – 64 | #50 | 0.07 |
| 3 – 48 | #47 | 0.0785 |
| 3 – 56 | #46 | 0.081 |
| 4 – 40 | #43 | 0.089 |
| 4 – 48 | #42 | 0.0935 |
| 5 – 40 | #38 | 0.1015 |
| 5 – 44 | #37 | 0.104 |
| 6 – 32 | #36 | 0.1065 |
| 6 – 40 | #33 | 0.113 |
| 8 – 32 | #29 | 0.136 |
| 8 – 36 | #29 | 0.136 |
| 10 – 24 | #26 | 0.147 |
| 10 – 32 | #21 | 0.159 |
| 12 – 24 | #16 | 0.177 |
| 12 – 28 | #15 | 0.18 |
| 14 – 20 | #10 | 0.1935 |
| 14 – 24 | #7 | 0.201 |
Metric Tap Drill Chart
| Tap Size | Drill Size (mm) | Decimal Value (in) |
| M1.6 × 0.35 | 1.25 | 0.0492 |
| M1.8 × 0.35 | 1.45 | 0.0571 |
| M2 × 0.4 | 1.6 | 0.063 |
| M2.2 × 0.45 | 1.75 | 0.0689 |
| M2.5 × 0.45 | 2.05 | 0.0807 |
| M3 × 0.5 | 2.5 | 0.0984 |
| M3.5 × 0.6 | 2.9 | 0.1142 |
| M4 × 0.7 | 3.3 | 0.1299 |
| M4.5 × 0.75 | 3.7 | 0.1476 |
| M5 × 0.8 | 4.2 | 0.1654 |
| M6 × 1.0 | 5 | 0.1969 |
| M7 × 1.0 | 6 | 0.2362 |
| M8 × 1.25 | 6.7 | 0.2638 |
| M8 × 1.0 | 7 | 0.2756 |
| M10 × 1.5 | 8.5 | 0.3346 |
| M10 × 1.25 | 8.7 | 0.3425 |
| M12 × 1.75 | 10.2 | 0.4016 |
| M12 × 1.25 | 10.8 | 0.4252 |
| M14 × 2.0 | 12 | 0.4224 |
| M16 × 2.0 | 14 | 0.5512 |
| M16 × 1.5 | 14.5 | 0.5906 |
| M18 × 2.5 | 15.5 | 0.6102 |
| M18 × 1.5 | 16.5 | 0.6496 |
| M20 × 2.5 | 17.5 | 0.689 |
| M20 × 1.5 | 18.5 | 0.7283 |
| M22 × 2.5 | 19.5 | 0.7677 |
| M22 × 1.5 | 20.5 | 0.8071 |
| M24 × 3.0 | 21 | 0.8268 |
| M24 × 2.0 | 22 | 0.8661 |
| M27 × 3.0 | 24 | 0.9449 |
| M27 × 2.0 | 25 | 0.9843 |
| M30 × 3.5 | 26.5 | 1.0433 |
| M30 × 2.0 | 28 | 1.1024 |
| M33 × 3.5 | 29.5 | 1.1614 |
| M33 × 2.0 | 31 | 1.2205 |
| M36 × 4.0 | 32 | 1.2598 |
| M36 × 3.0 | 33 | 1.2992 |
| M39 × 4.0 | 35 | 1.378 |
| M39 × 3.0 | 36 | 1.4173 |
Fractional Inch Tap Drill Sizes
| Tap Size (in) | Drill Size | Decimal Value (in) |
| 1/4 – 20 | #7 | 0.201 |
| 1/4 – 28 | #3 | 0.213 |
| 5/16 – 18 | F | 0.257 |
| 5/16 – 24 | I | 0.272 |
| 3/8 – 16 | 5/16 | 0.3125 |
| 3/8 – 24 | Q | 0.332 |
| 7/16 – 14 | U | 0.368 |
| 7/16 – 20 | 25/64 | 0.3906 |
| 1/2 – 13 | 27/67 | 0.4219 |
| 1/2 – 20 | 29/64 | 0.4531 |
| 9/16 – 12 | 31/64 | 0.4844 |
| 9/16 – 18 | 33/64 | 0.5156 |
| 5/8 – 11 | 14/32 | 0.5312 |
| 5/8 – 18 | 37/64 | 0.5781 |
| 3/4 – 10 | 21/32 | 0.6562 |
| 3/4 – 16 | 11/16 | 0.6875 |
| 7/8 – 9 | 49/64 | 0.7656 |
| 7/8 – 14 | 13/16 | 0.8125 |
| 1 – 8 | 7/8 | 0.875 |
| 1 – 12 | 59/64 | 0.9219 |
| 1-1/8 – 7 | 63/64 | 0.9844 |
| 1-1/8 – 12 | 1-3/64 | 1.0469 |
| 1-1/4 – 7 | 1-7/64 | 1.1094 |
| 1-1/4 – 12 | 1-11/64 | 1.1719 |
| 1-3/8 – 6 | 1-7/32 | 1.2188 |
| 1-3/8 – 12 | 1-19/64 | 1.2969 |
| 1-1/2 – 6 | 1-11/32 | 1.3438 |
| 1-1/2 – 12 | 1-27/64 | 1.4219 |
Unified National Coarse Tap Drill Sizes
| Tap Size | Drill Size | Decimal Value (in) |
| 1 – 64 | #53 | 0.0595 |
| 2 – 56 | #50 | 0.07 |
| 3 – 48 | #47 | 0.0785 |
| 4 – 40 | #43 | 0.089 |
| 5 – 40 | #38 | 0.1015 |
| 6 – 32 | #36 | 0.1065 |
| 8 – 32 | #29 | 0.136 |
| 10 – 24 | #26 | 0.147 |
| 12 – 24 | #16 | 0.177 |
| 1/4 – 20 | #7 | 0.201 |
| 5/16 – 18 | F | 0.257 |
| 3/8 – 16 | 5/16 | 0.3125 |
| 7/16 – 14 | U | 0.368 |
| 1/2 – 13 | 27/64 | 0.368 |
| 9/16 – 12 | 31/64 | 0.4844 |
| 5/8 – 11 | 17/32 | 0.5312 |
| 3/4 – 10 | 21/32 | 0.6562 |
| 7/8 – 9 | 49/64 | 0.7656 |
| 1 – 8 | 7/8 | 0.875 |
| 1-1/8 – 7 | 63/34 | 0.9844 |
| 1-1/4 – 7 | 1-7/64 | 1.1094 |
| 1-3/8 – 6 | 1-1/64 | 1.2188 |
| 1-1/2 – 6 | 1-11/54 | 1.3438 |
Unified National Fine Tap Drill Sizes
| Tap Size | Drill Size | Decimal Value (in) |
| 0 – 80 | 3/64” | 0.0469 |
| 1 – 72 | #53 | 0.0595 |
| 2 – 64 | #50 | 0.07 |
| 3 – 56 | #46 | 0.081 |
| 4 – 48 | #42 | 0.0935 |
| 5 – 44 | #37 | 0.104 |
| 6 – 40 | #33 | 0.113 |
| 8 – 36 | #29 | 0.136 |
| 10 – 32 | #21 | 0.159 |
| 12 – 28 | #15 | 0.18 |
| 1/4 – 28 | #3 | 0.213 |
| 5/16 – 24 | I | 0.272 |
| 3/8 – 24 | Q | 0.332 |
| 7/16 – 20 | 25/64 | 0.3906 |
| 1/2 – 20 | 29/64 | 0.4531 |
| 9/16 – 18 | 33/64 | 0.5156 |
| 5/8 – 18 | 37/64 | 0.5781 |
| 3/4 – 16 | 11/16 | 0.6875 |
| 7/8 – 14 | 13/16 | 0.8125 |
| 1 – 12 | 59/64 | 0.9219 |
| 1-1/8 – 12 | 1-3/64 | 1.0469 |
| 1-1/4 – 12 | 1-11/64 | 1.1719 |
| 1-3/8 – 12 | 1-19/64 | 1.2969 |
| 1-1/2 – 12 | 1-27/64 | 1.4219 |
National Standard Tap Drill Sizes
| Tap Size | Drill Size |
| 5/32 – 32 | 1/8 |
| 5/32 – 36 | #30 |
| 3/16 – 24 | #26 |
| 3/16 – 32 | #22 |
| 7/32 – 24 | #16 |
| 7/32 – 32 | #12 |
| 1/4 – 32 | 7/32 |
| 1/4 – 40 | #1 |
| 5/16 – 32 | 9/32 |
| 11/16 – 16 | 5/8 |
| 1 – 14 | 15/16 |
National Pipe Thread Tap Drill Sizes
| Tap Size | Drill Size |
| 1/8 – 27 | Q |
| 1/4 – 18 | 7/16 |
| 3/8 – 18 | 9/16 |
| 1/2 – 14 | 23/32 |
| 3/4 – 14 | 59/64 |
| 1 – 11-1/2 | 1-5/32 |
| 1-1/4 – 11-1/2 | 1-1/2 |
| 1-1/2 – 11-1/2 | 1-47/64 |
| 2 – 11-1/2 | 2-7/32 |
FAQs:
For a 3/4-inch tap, you typically need a hole size of around 0.6875 inches (17.46 mm) for 10 threads per inch (TPI) and about 0.7031 inches (17.86 mm) for 16 TPI.
The rule of thumb for tap drill size is to subtract the thread pitch from the major diameter, typically resulting in a hole size slightly smaller than the desired thread.
To tap a 3/4″-16 hole, you should use a drill bit that measures 11/16 inches or about 17.46 mm in diameter. This provides the correct clearance for the tap.
The correct tap drill size for a 3/4″-14 NPT (National Pipe Taper) thread is typically 59/64 inch or about 23.42 millimeters. This allows for proper thread engagement.
Conclusion
To wrap up, a tap drill chart is a must-have tool for machinists and engineers. It helps ensure accurate thread creation and better tap performance. Using this chart can greatly improve the precision of your drilling projects, leading to better-fitting and longer-lasting threaded components. The key to successful tapping is choosing the correct drill size based on the chart for the screw size and material hardness. Use this tool to boost the precision and efficiency of your machining tasks.
