Quick answer: a "1 inch rubber washer" is either 1" across the outside (1" OD) or has a 1" hole (1" ID). They are very different parts. A 1" OD washer is a coin-sized washer for bolts from 1/8" to 3/4"; we list 71. A 1" ID washer fits over a 1" bolt, rod or shaft and is at least 1-1/4" across; we list 84. If the washer goes over 1" pipe or tube, size the hole to the pipe's real outside diameter, which is larger than 1".
How to tell which one you need
- Replacing an old washer? Measure it. If the outside is about 1" (25 mm), you need a 1" OD. Then measure the hole and thickness. How to measure a rubber washer shows the method.
- Fitting it over something? Measure that part. A 1" bolt, rod or shaft takes a 1" ID. A pipe or tube takes an ID that matches its outside diameter.
- Bought by a hardware list? Lists usually give the fastener size, which means the ID.
1" OD rubber washers
A 1" OD is one of the most popular washer sizes because it gives a good sealing ring around bolts from about 1/4" to 1/2". We list it with these holes, each in 7 thicknesses from 1/16" to 1/2" (plus a 1/32" option with a 3/8" hole):
| Hole (ID) | Common fastener | Rubber ring width |
|---|---|---|
| 1/8" | Small screws, pins | 7/16" |
| 3/16" | #8 to #10 screws | 13/32" |
| 1/4" | 1/4" bolts, #14 screws, M6 | 3/8" |
| 5/16" | 5/16" bolts, M8 | 11/32" |
| 3/8" | 3/8" bolts | 5/16" |
| 7/16" | 7/16" bolts, M10 | 9/32" |
| 1/2" | 1/2" bolts, M12 | 1/4" |
| 9/16" | 9/16" bolts, M14 | 7/32" |
| 5/8" | 5/8" bolts | 3/16" |
| 3/4" | 3/4" bolts, rods | 1/8" |
The "ring width" is how much rubber surrounds the hole: (OD − ID) ÷ 2. A wider ring seals and cushions better. A very narrow ring (1/8") is delicate and best for light-duty use. Shop the 1" OD rubber washers collection.
1" ID rubber washers
For 1" bolts, rods, shafts and studs. Each OD is listed in the thicknesses shown and in seven materials.
| OD with a 1" hole | Thicknesses listed |
|---|---|
| 1-1/4" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 1-3/8" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 1-1/2" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 1-5/8" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 1-3/4" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 2" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 2-1/4" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 2-1/2" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 2-3/4" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 3" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 3-1/2" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
| 4" | 1/16", 3/32", 1/8", 3/16", 1/4", 3/8", 1/2" |
A 1-1/2" to 2" OD is a balanced choice for a 1" bolt. Go up to 2-1/2" to 4" OD to spread the load on soft material, cover a large or damaged hole, or make a broad cushion. Browse the 1" ID rubber washers collection.
Washers for 1" pipe and tube
| Part | Actual OD | Washer ID to start with |
|---|---|---|
| 1" bolt, rod or shaft | 1.000" | 1" ID |
| 1" nominal copper tube or PEX | 1.125" | 1-3/16" ID, e.g. our 2-1/4" OD x 1-3/16" ID x 1/8" |
| 1" nominal steel or PVC pipe (NPS 1) | 1.315" | 1-3/8" ID, e.g. our 2-1/2" OD x 1-3/8" ID x 1/8" |
Copper tube ODs follow ASTM B88 and steel pipe ODs follow ASME B36.10M; PVC pipe uses the same ODs. Always confirm with calipers, especially on older or imported fittings.
Choosing thickness and material
For sealing two flat faces, 1/16" to 1/8" is usually best. For cushioning and vibration isolation, choose 3/16" to 1/2". Thick washers squeeze out sideways when tightened, so don't go thick just to be safe.
| Material | Usual choice for |
|---|---|
| Neoprene | All-purpose sealing and cushioning, indoors and out |
| EPDM | Water, steam, sunlight and ozone; not petroleum oils |
| Nitrile | Oil, fuel and grease |
| Silicone | High and low temperatures, food-contact equipment |
| Viton | Aggressive chemicals, fuels and high heat |
| Natural rubber | Shock and vibration absorption |
| Fiber | Firm, dry gasketing on fittings |
1" washers ready to ship (October 2026)
These 1" OD and 1" ID sizes had at least one material in stock when this guide was updated.
| OD | ID | Thick | In stock in | |
|---|---|---|---|---|
| 2-1/2" | 1" | 1/8" | Neoprene | View size |
| 2" | 1" | 1/8" | Neoprene | View size |
| 2" | 1" | 3/32" | EPDM | View size |
| 1-1/2" | 1" | 1/4" | Neoprene | View size |
| 1-3/8" | 1" | 3/32" | Neoprene | View size |
| 1" | 3/8" | 1/32" | Neoprene | View size |
| 1" | 3/4" | 1/8" | Neoprene | View size |
| 1" | 1/2" | 1/8" | Neoprene | View size |
| 1" | 3/8" | 1/8" | Neoprene | View size |
| 1" | 3/8" | 1/16" | Neoprene | View size |
FAQ
Is a 1 inch rubber washer measured on the inside or the outside?
Either, depending on who's describing it. Product lists usually say both. If yours only says "1 inch", measure the old washer or the part it fits over.
What size rubber washer fits a 1" pipe?
1" steel or PVC pipe is 1.315" across, so a 1-3/8" ID washer slips over it. 1" copper or PEX is 1.125" across, so a 1-3/16" ID fits.
What hole sizes come with a 1" OD washer?
We list 1/8", 3/16", 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8" and 3/4" holes with a 1" OD.
Can I find a washer by OD, ID and thickness at once?
Yes. The rubber washer size finder filters the whole catalogue of 1,746 sizes by all three dimensions in a few taps.