When searching for the best micro screws for your next project, you may run into the issue of not knowing which size you need. To ensure you’re choosing the right screw measurements, check out our screw size conversion table so your project will go off without a hitch.
U.S. Screw Size Conversion Chart
Below, you’ll find our chart displaying the different U.S. screw sizes, with their accompanying measurements in decimal inches, fractional inches, metric sizing, and common TPI range.
| U.S. Screw Size | Decimal Inches | Fractional Inches | Metric (mm) | Common TPI Range |
|---|---|---|---|---|
| #0 | 0.060" | 1/16" | 1.52 mm | 80 |
| #1 | 0.073" | 5/64" | 1.85 mm | 64, 72 |
| #2 | 0.086" | 3/32" | 2.18 mm | 56, 64 |
| #3 | 0.099" | 7/64" | 2.51 mm | 48, 56 |
| #4 | 0.112" | 7/64" | 2.84 mm | 40, 48 |
| #5 | 0.125" | 1/8" | 3.18 mm | 40, 44 |
| #6 | 0.138" | 9/64" | 3.51 mm | 32, 40 |
| #8 | 0.164" | 5/32" | 4.17 mm | 32, 36 |
| #10 | 0.190" | 3/16" | 4.83 mm | 24, 32 |
| #12 | 0.216" | 7/32" | 5.49 mm | 24, 28 |
| 1/4" | 0.250" | 1/4" | 6.35 mm | 20, 28, 80 |
| 5/16" | 0.3125" | 5/16" | 7.94 mm | 18, 24 |
| 3/8" | 0.375" | 3/8" | 9.53 mm | 16, 24 |
| 7/16" | 0.4375" | 7/16" | 11.11 mm | 14, 20 |
| 1/2" | 0.500" | 1/2" | 12.70 mm | 13, 20 |
FAQs About Understanding U.S. Fastener Sizes
What do U.S. screw sizes actually measure?
U.S. screw sizes measure the diameter and threads per inch (TPI), representing the thread count. For example, a ¼-80 fine adjustment screw means the screw has a ¼ inch diameter, and 80 threads per inch.
If I have an existing screw that I want more of, how can I go about measuring it accurately?
If you’re looking to measure an existing screw, you can use a digital caliper. This device will measure the screw’s diameter and length. You can also contact our team for assistance and we can make recommendations.
When looking at the chart above, are the U.S. sizes identical to the metric sizes?
The U.S. sizes and metric sizes will be similar but are not completely interchangeable. This is due to the differences in thread pitch and diameter.
How can I calculate TPI?
If you’re looking to calculate the TPI of your screw, you can use this formula:
Threads per inch = number of threads / length of the thread
Why is it essential that I have the right screw size for my application?
Having the correct screw size is highly important for both safety and functionality reasons. An incorrectly sized screw can cause the following issues:
- Weak joints on a final product, making breakage or other issues more likely
- Damage to materials if the screw is too large
- Incompatibility with other parts of a project if predrilled holes exist
How Kozak Can Deliver the Exact Screw You Need
After reviewing our screw size conversion table, you may now know the specific screw you need but still might not be able to find it. You’re in luck because Kozak Micro Adjusters offers custom screws, so you can contact us for products that will be the perfect fit for your next project.
Our team can manufacture diverse screws, including those using imperial (U.S.) or metric sizing, while supplying key customizations for length, drive variation, material, and custom tips. No matter if your application requires 1 or 1 million components, we have the capability to fulfill your project needs and meet exacting requirements.
We also have extensive experience working with a wide range of industries, such as:
To get started on a custom screw project with us, fill out the form on our website, or send us an email with your own drawing at info@kozakmicro.com.
Have Additional Questions About Our Screw Size Conversion Table?
Reach out to our team today and we’ll help you understand U.S. fastener sizes to ensure you find the right screw for your next project.