US Fastener Sizes and Conversion Charts
Understanding US Fastener Sizes
Fasteners come in various sizes and measurements, which can be confusing when trying to select the right one for your project. Knowing the decimal equivalent for a US screw size is very helpful, especially when using digital calipers to measure screw sizes or when you need to drill a hole to match a screw size. This guide provides conversion charts to help you find the correct fastener size.
US Screw Size Conversion Chart
The following chart converts US screw sizes to their decimal (inch) and metric (millimeter) equivalents, as well as the nearest fractional size.
| Screw Size | Inch Decimal | Nearest Fraction | Metric Equivalent |
|---|---|---|---|
| #0 | 0.060 in. | 1/16" | 1.52 mm |
| #1 | 0.073 in. | 5/64" | 1.85 mm |
| #2 | 0.086 in. | 3/32" | 2.18 mm |
| #3 | 0.099 in. | 7/64" | 2.51 mm |
| #4 | 0.112 in. | 7/64" | 2.84 mm |
| #5 | 0.125 in. | 1/8" | 3.18 mm |
| #6 | 0.138 in. | 9/64" | 3.51 mm |
| #8 | 0.164 in. | 5/32" | 4.17 mm |
| #10 | 0.190 in. | 3/16" | 4.83 mm |
| #12 | 0.216 in. | 7/32" | 5.49 mm |
| #14 | 0.250 in. | 1/4" | 6.35 mm |
US Fraction to Metric mm Equivalent Chart
This chart converts common US fractional sizes to their metric equivalents up to 4 inches.
| US | Metric | US | Metric | |
|---|---|---|---|---|
| 1/16" | 1.59 mm | 1-3/8" | 34.93 mm | |
| 1/8" | 3.18 mm | 1-1/2" | 38.10 mm | |
| 3/16" | 4.76 mm | 1-5/8" | 41.28 mm | |
| 1/4" | 6.35 mm | 1-3/4" | 44.45 mm | |
| 5/16" | 7.94 mm | 1-7/8" | 47.63 mm | |
| 3/8" | 9.53 mm | 2" | 50.80 mm | |
| 7/16" | 11.11 mm | 2-1/4" | 57.15 mm | |
| 1/2" | 12.70 mm | 2-1/2" | 63.50 mm | |
| 9/16" | 14.29 mm | 2-3/4" | 69.85 mm | |
| 5/8" | 15.88 mm | 3" | 76.20 mm | |
| 11/16" | 17.46 mm | 3-1/4" | 82.55 mm | |
| 3/4" | 19.05 mm | 3-1/2" | 88.90 mm | |
| 7/8" | 22.23 mm | 3-3/4" | 95.25 mm | |
| 1" | 25.40 mm | 4" | 101.6 mm | |
| 1-1/4" | 31.75 mm |
Frequently Asked Questions
- Why are there different screw size standards?
Different screw size standards exist because they were developed to meet specific regional or industry requirements. The US uses the Imperial system while most of the world uses the Metric system.
- How do I measure screw size accurately?
To measure screw size accurately, use a digital caliper to measure the diameter and length. Refer to conversion charts to find the equivalent sizes if needed.
- What do the numbers on screws mean?
The numbers on screws (such as #6, #8, etc.) refer to the diameter of the screw. Higher numbers indicate larger diameters.
- Can I use a screw size chart for bolts as well?
Yes, you can use a screw size chart for bolts as they follow similar sizing standards. However, ensure to check if the specific application has any special requirements.
- What are the most common types of fasteners used in construction?
- How do fastener sizes affect load-bearing capacity?
- Why is it important to match screw sizes with pilot hole sizes?
- What are some considerations when selecting fasteners for outdoor applications?
- How do I determine the thread pitch of a fastener?