Washers may seem like simple hardware, but choosing the correct size is essential for ensuring proper load distribution and secure fastening. This chart covers standard dimensions for both SAE and USS flat washers, making it easier to find the right fit for your application. Whether you’re checking inner diameter, outer diameter, or thickness, you’ll find the key specs here.
USS Flat Washers
| Screw Size | Inside Diameter (inches) |
Outside Diameter (inches) |
Thickness (inches) |
Inside Diameter (mm) |
Outside Diameter (mm) |
Thickness (mm) |
|---|---|---|---|---|---|---|
| 3/16″ | 7/32 | 1/2 | 1/32 | 5.56 | 12.70 | 0.81 |
| 1/4″ | 9/32 | 5/8 | 1/16 | 7.14 | 15.88 | 1.65 |
| 5/16″ | 11/32 | 11/16 | 1/16 | 8.74 | 17.48 | 1.65 |
| 3/8″ | 13/32 | 13/16 | 1/16 | 10.31 | 20.62 | 1.65 |
| 7/16″ | 15/32 | 7/8 | 1/16 | 11.91 | 22.23 | 1.65 |
| 1/2″ | 17/32 | 1 | 3/32 | 13.49 | 25.40 | 2.41 |
| 9/16″ | 19/32 | 1-1/16 | 3/32 | 15.09 | 26.97 | 2.41 |
| 5/8″ | 21/32 | 1-1/4 | 3/32 | 16.66 | 31.75 | 2.41 |
| 3/4″ | 13/16 | 1-1/2 | 9/64 | 20.62 | 38.10 | 3.40 |
| 7/8″ | 15/16 | 1-3/4 | 9/64 | 23.83 | 44.45 | 3.40 |
| 1″ | 1-1/16 | 2 | 9/64 | 26.97 | 50.80 | 3.40 |
| 1-1/8″ | 1-5/32 | 2-1/4 | 9/64 | 30.16 | 57.15 | 3.40 |
| 1-1/4″ | 1-5/16 | 2-1/2 | 5/32 | 33.34 | 63.50 | 3.97 |
| 1-3/8″ | 1-7/16 | 2-3/4 | 5/32 | 36.51 | 69.85 | 3.97 |
| 1-1/2″ | 1-5/8 | 3 | 5/32 | 41.28 | 76.20 | 3.97 |
| 1-5/8″ | 1-3/4 | 3-1/4 | 5/32 | 44.45 | 82.55 | 3.97 |
| 1-3/4″ | 1-7/8 | 3-1/2 | 5/32 | 47.63 | 88.90 | 3.97 |
| 2″ | 2-1/8 | 4 | 3/16 | 53.98 | 101.60 | 4.76 |
| 2-1/4″ | 2-3/8 | 4-1/2 | 3/16 | 60.33 | 114.30 | 4.76 |
| 2-1/2″ | 2-5/8 | 5 | 3/16 | 66.68 | 127.00 | 4.76 |
| 2-3/4″ | 2-7/8 | 5-1/2 | 3/16 | 73.03 | 139.70 | 4.76 |
| 3″ | 3-1/8 | 6 | 1/4 | 79.38 | 152.40 | 6.35 |
SAE Flat Washers
| Screw Size | Inside Diameter (inches) |
Outside Diameter (inches) |
Thickness (inches) |
Inside Diameter (mm) |
Outside Diameter (mm) |
Thickness (mm) |
|---|---|---|---|---|---|---|
| 3/16″ | 7/32 | 7/16 | 1/16 | 5.56 | 11.11 | 1.59 |
| 1/4″ | 17/64 | 9/16 | 1/16 | 6.75 | 14.29 | 1.59 |
| 5/16″ | 21/64 | 5/8 | 1/16 | 8.33 | 15.88 | 1.59 |
| 3/8″ | 25/64 | 3/4 | 1/16 | 9.92 | 19.05 | 1.59 |
| 7/16″ | 29/64 | 13/16 | 1/16 | 11.51 | 20.64 | 1.59 |
| 1/2″ | 33/64 | 7/8 | 1/16 | 13.10 | 22.23 | 1.59 |
| 9/16″ | 37/64 | 15/16 | 1/16 | 14.68 | 23.81 | 1.59 |
| 5/8″ | 41/64 | 1-1/16 | 1/16 | 16.27 | 26.99 | 1.59 |
| 3/4″ | 49/64 | 1-1/4 | 5/64 | 19.45 | 31.75 | 1.98 |
| 7/8″ | 57/64 | 1-7/16 | 5/64 | 22.62 | 36.51 | 1.98 |
| 1″ | 1-1/32 | 1-5/8 | 5/64 | 26.19 | 41.28 | 1.98 |
| 1-1/8″ | 1-5/32 | 1-13/16 | 5/64 | 29.37 | 46.04 | 1.98 |
| 1-1/4″ | 1-5/16 | 2 | 5/64 | 33.34 | 50.80 | 1.98 |
| 1-3/8″ | 1-7/16 | 2-3/16 | 5/64 | 36.51 | 55.56 | 1.98 |
| 1-1/2″ | 1-5/8 | 2-3/8 | 5/64 | 41.28 | 60.33 | 1.98 |
| 1-5/8″ | 1-3/4 | 2-9/16 | 5/64 | 44.45 | 65.09 | 1.98 |
| 1-3/4″ | 1-7/8 | 2-3/4 | 5/64 | 47.63 | 69.85 | 1.98 |
| 2″ | 2-1/8 | 3 | 3/32 | 53.98 | 76.20 | 2.38 |
| 2-1/4″ | 2-3/8 | 3-3/8 | 3/32 | 60.33 | 85.73 | 2.38 |
| 2-1/2″ | 2-5/8 | 3-3/4 | 3/32 | 66.68 | 95.25 | 2.38 |
| 2-3/4″ | 2-7/8 | 4-1/8 | 3/32 | 73.03 | 104.78 | 2.38 |
| 3″ | 3-1/8 | 4-1/2 | 3/32 | 79.38 | 114.30 | 2.38 |
Parting Thoughts
MISUMI USA offers a wide range of washers and fasteners—both standard and configurable—including flat washers, spring washers, lock washers, and more. If you’re unsure which washer product best suits your application, our engineering team is here to help. For more technical insights, explore our other manufacturing-focused tables and articles, such as a machine screw size chart.
Browse Washer ProductsAuthor: Scott Bredemann | Updated: 6/26/2025
Disclaimer:
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers’ or manufacturers’ deliverables within MISUMI’s network. Buyers are responsible for specifying their part requirements