.png)
Ultimate Tap Drill Size & Conversion Chart for Industrial & Manufacturing Applications
- Kelly Industrial
- 4 days ago
- 2 min read
Updated: 3 days ago
Nothing disrupts production faster than stripped threads, broken taps, or scrap parts caused by incorrect drill sizing. In industrial machining and manufacturing environments, even minor errors in tap drill selection can lead to downtime, tool breakage, and costly rework.
This guide serves as a one-stop reference for machinists, manufacturers, and procurement teams, providing accurate tap drill sizes for standard Imperial (SAE) and Metric threads. It also includes a master conversion table to quickly switch between fractions, decimals, and millimeters—ideal for mixed-unit production environments.
Imperial / SAE Tap & Drill Sizes
How to Use This Chart:
Match the tap size and thread pitch (TPI) to the recommended drill size to ensure proper thread engagement. Always verify thread class and material before drilling.
Course Thread
Tap Size | Drill Size | Tap Size | Drill Size |
4-40 | No. 43 | 5/16 | ‘F’ |
5-40 | No. 38 | 3/8-16 | 5/16 |
6-32 | No. 36 | 7/16-14 | ‘U’ |
8-32 | No. 29 | 1/2-13 | 27/64 |
10-24 | No. 25 | 9/16-12 | 31/64 |
12-24 | No. 16 | 5/8-11 | 17/32 |
1/4-20 | No. 7 | 3/4-10 | 21/32 |
Fine Thread
Tap Size | Drill Size | Tap Size | Drill Size |
5-44 | No. 36 | 3/8-24 | ‘Q’ |
6-40 | No. 29 | 7/16-20 | 25/64 |
8-36 | No. 25 | 1/2-20 | 29/64 |
10-32 | No. 16 | 9/16-18 | 33/64 |
12-28 | No. 7 | 5/8-18 | 37/64 |
1/4-28 | No. 3 | 3/4-16 | 11/16 |
5/16-24 | ‘I’ | 7/8-14 | 13/16 |
Metric Tap & Drill Sizes
Metric taps are identified by their nominal diameter (e.g., M10) and their pitch (the distance between threads in mm). Warning: Always verify the pitch before drilling, especially with M10 and M12 sizes, which have multiple common variations.
Course Pitch
Tap Size | Pitch (mm) | Drill Size (mm) | Tap Size | Pitch (mm) | Drill Size (mm) |
M2 | 0.4 | 1.6 | M11 | 1.5 | 9.5 |
M3 | 0.5 | 2.5 | M12 | 1.75 | 10.2 |
M4 | 0.7 | 3.3 | M14 | 2.0 | 12.0 |
M5 | 0.8 | 4.2 | M16 | 2.0 | 14.0 |
M6 | 1.0 | 5.0 | M18 | 2.5 | 15.5 |
M7 | 1.0 | 6.0 | M20 | 2.5 | 17.5 |
M8 | 1.25 | 6.75 | M22 | 2.5 | 19.5 |
M9 | 1.25 | 7.75 | M24 | 3.0 | 21.0 |
M10 | 1.5 | 8.5 |
Fine Pitch
Tap Size | Pitch (mm) | Drill Size (mm) | Tap Size | Pitch (mm) | Drill Size (mm) |
M8 | 1.0 | 7.0 | M18 | 1.5 | 16.5 |
M10 | 1.25 | 8.75 | M20 | 2.0 | 18.0 |
M12 | 1.5 | 10.5 | M22 | 2.0 | 20.0 |
M14 | 1.5 | 12.5 | M24 | 2.0 | 22.0 |
M16 | 1.5 | 14.5 |
BONUS
Master Conversion Chart (Inches to MM)
Don't have the exact numbered drill bit listed above? Use this conversion chart to find the closest fractional or metric equivalent in your toolbox. This table covers the essential "anchor" sizes in 1/16" increments.
Upgrade Your Shop Precision
For a complete workshop reference that goes beyond standard sizes, we’ve compiled a full technical guide designed for machine shops, OEMs, and industrial maintenance teams. This extended version includes wire gauge drill sizes, alternate thread pitches, and clearance hole specifications used in production machining.
Comments