Screw size chart
Three screw families, kept apart because they use different diameters, threads and holes.
The machine screw chart covers #0 to 1 inch in UNC and UNF threads. The metric chart covers M1.6 to M24. The wood screw chart covers #2 to #14 and gives pilot holes.
20 rows
| Size | Diameter (in) | Diameter (mm) | UNC | UNF |
|---|---|---|---|---|
| #0 | 0.0600 | 1.524 | - | 80 TPI, tap 3/64 |
| #1 | 0.0730 | 1.854 | 64 TPI, tap #53 | 72 TPI, tap #53 |
| #2 | 0.0860 | 2.184 | 56 TPI, tap #50 | 64 TPI, tap #50 |
| #3 | 0.0990 | 2.515 | 48 TPI, tap #47 | 56 TPI, tap #45 |
| #4 | 0.1120 | 2.845 | 40 TPI, tap #43 | 48 TPI, tap #42 |
| #5 | 0.1250 | 3.175 | 40 TPI, tap #38 | 44 TPI, tap #37 |
| #6 | 0.1380 | 3.505 | 32 TPI, tap #36 | 40 TPI, tap #33 |
| #8 | 0.1640 | 4.166 | 32 TPI, tap #29 | 36 TPI, tap #29 |
| #10 | 0.1900 | 4.826 | 24 TPI, tap #25 | 32 TPI, tap #21 |
| #12 | 0.2160 | 5.486 | 24 TPI, tap #16 | 28 TPI, tap #14 |
| 1/4 | 0.2500 | 6.35 | 20 TPI, tap #7 | 28 TPI, tap #3 |
| 5/16 | 0.3125 | 7.938 | 18 TPI, tap F | 24 TPI, tap I |
| 3/8 | 0.3750 | 9.525 | 16 TPI, tap 5/16 | 24 TPI, tap Q |
| 7/16 | 0.4375 | 11.112 | 14 TPI, tap U | 20 TPI, tap 25/64 |
| 1/2 | 0.5000 | 12.7 | 13 TPI, tap 27/64 | 20 TPI, tap 29/64 |
| 9/16 | 0.5625 | 14.288 | 12 TPI, tap 31/64 | 18 TPI, tap 33/64 |
| 5/8 | 0.6250 | 15.875 | 11 TPI, tap 17/32 | 18 TPI, tap 37/64 |
| 3/4 | 0.7500 | 19.05 | 10 TPI, tap 21/32 | 16 TPI, tap 11/16 |
| 7/8 | 0.8750 | 22.225 | 9 TPI, tap 49/64 | 14 TPI, tap 13/16 |
| 1 | 1.0000 | 25.4 | 8 TPI, tap 7/8 | 12 TPI, tap 59/64 |
Need the drill bit? Use the drill bit to screw size chart.
Choosing the right chart
Start with how the screw is labelled. A letter M followed by a number means metric. A # sign, or a fraction such as 1/4, means an inch size. If the screw has a sharp tapered point and a deep thread, it is almost certainly a wood screw. The explorer above searches one family at a time because the same number means different things in each: #8 is 0.164 in for both machine and wood screws, but the thread, the tap drill and the clearance hole all differ.
If you only have the screw in your hand, measure the outside of the thread with a caliper and use Match my screw on the drill bit page. Measure the thread crests, not the head, and expect a small error.