Finding the right replacement rubber washer starts with three measurements: outer diameter (OD), inner diameter (ID), and thickness. Here's exactly how to measure each one. Already know your measurements? Jump straight to the rubber washer size chart to find your match.
What You'll Need
- A caliper (digital or vernier) for accurate measurements
- Or a ruler for approximate measurements
- The washer you need to replace (if available)
Step 1 — Measure the Outer Diameter (OD)
The outer diameter is the total width of the washer from one outside edge to the other. Place your caliper across the widest point of the washer. This is your OD measurement.
Step 2 — Measure the Inner Diameter (ID)
The inner diameter is the size of the hole in the center of the washer. Insert your caliper into the hole and measure across. This is your ID measurement — it should match or slightly exceed the bolt or fitting diameter it will sit on.
Step 3 — Measure the Thickness
Lay the washer flat and measure its height with your caliper. This is the thickness. Thickness affects how much compression and sealing force the washer provides.
Tips for Finding the Right Size
- If your washer is worn or compressed, measure the bolt/fitting ID instead and add 1/16" to 1/8" for the washer ID
- OD should be large enough to cover the surface area you need to seal or protect
- When in doubt, go slightly larger on OD and slightly smaller on ID for a better seal
- All our washers are listed by OD x ID x Thickness — e.g., 3/4" OD x 3/8" ID x 1/16" Thick
Browse by Dimension
- Full size chart — browse by OD, ID or thickness
- Most popular OD: 3/4"
- Most popular ID: 1/4"
- Most popular thickness: 1/8"
Frequently Asked Questions
How do I measure a rubber washer?
Measure three dimensions with a caliper: the outer diameter (OD) across the widest point, the inner diameter (ID) across the center hole, and the thickness with the washer laid flat. Every washer we sell is listed as OD x ID x Thickness.
What is the difference between a washer's OD and ID?
The OD (outer diameter) is the total width from one outside edge to the other. The ID (inner diameter) is the center hole that slips over your bolt or fitting. The ID should match or slightly exceed the bolt diameter it sits on.
How do I find the right size if my old washer is worn or compressed?
Measure the bolt or fitting diameter instead, then add about 1/16" to 1/8" for the washer ID. Pick an OD large enough to cover the surface you need to seal or protect.
How do I choose the right washer thickness?
Thickness controls how much compression and sealing force a washer provides. Thinner washers are best for sealing and gasketing, while thicker washers cushion and absorb vibration. Lay the washer flat and measure its height to get the thickness.
Do I need a caliper to measure a rubber washer?
A digital or vernier caliper gives the most accurate reading, especially for the inner diameter and thickness. A ruler works for approximate sizing if you don't have a caliper.
How are your rubber washers sized?
Each washer is listed by OD x ID x Thickness, for example 3/4" OD x 3/8" ID x 1/16" Thick. You can browse the size chart by outer diameter, inner diameter, or thickness to find your size.