To determine the correct washer size for a bolt, simply match the washer's stated size to the diameter of the bolt you are using.
Understanding washer sizes is straightforward once you know the basic principle. Washer sizes are standardized to correspond directly with the diameter of the bolt or screw they are intended to fit.
Matching Washer Size to Bolt Diameter
The most crucial rule is that the listed size of the washer refers to the nominal size of the bolt.
- Washer size matches bolt diameter: According to common practice, washer sizes correspond to the screw/bolt diameter they fit. This means if you have a 1/4-inch bolt, you will look for a 1/4-inch washer.
- Inner Diameter is Slightly Larger: While the washer's stated size matches the bolt diameter, its actual inner hole diameter is manufactured to be slightly larger than the bolt's diameter. This allows the bolt to pass through easily. For example, a 1/2” washer fits a 1/2” bolt, and therefore has an inner diameter of just over 1/2”.
This slight difference ensures a proper fit without being too loose or too tight.
Practical Steps
- Identify the Bolt Diameter: Determine the diameter of the bolt you need a washer for. Bolt diameters are typically measured across the threaded part.
- If you know the bolt size already (e.g., from the packaging or specifications), use that size.
- If you don't know the size, you can measure the bolt's diameter using a caliper or a bolt measuring tool.
- Select the Corresponding Washer Size: Choose a washer with the same stated size as your bolt diameter.
Common Examples
Here's a simple illustration based on standard sizing:
| Bolt Diameter | Corresponding Washer Size |
|---|---|
| 1/4 inch | 1/4 inch |
| 3/8 inch | 3/8 inch |
| 1/2 inch | 1/2 inch |
| M6 (Metric) | M6 (Metric) |
| M8 (Metric) | M8 (Metric) |
Remember that while the stated size matches the bolt, the actual hole in the washer will be slightly larger to accommodate the bolt shaft.
By simply matching the nominal washer size to the bolt's diameter, you can easily determine the correct washer to use for your fastening application.
