An M3 bolt is 3.00 mm (0.118") in diameter. The stocked match is a 1/8" (3.18 mm) inside diameter — 0.18 mm of clearance, ideal for electronics, enclosures, small appliances and instrument panels. Every size ships in Neoprene, EPDM, Nitrile, Silicone, Natural Rubber, Viton and Fiber.
Best in-stock matches for M3
| Washer size | Fit |
|---|---|
| 5/16" OD × 1/8" ID × 1/16" | Compact, electronics-scale |
| 3/8" OD × 1/8" ID × 1/16" | General purpose |
| 1/2" OD × 1/8" ID × 1/16" | Wider sealing face |
| 3/4" OD × 1/8" ID × 1/8" | Fender-style coverage |
Browse every 1/8" ID rubber washer — including micro sizes down to 3/16" OD and 1/32" thickness.
Sizing note
At M3 scale, thin washers (1/32"–1/16") preserve stack height in tight assemblies; use silicone for heat near electronics and fiber when you need a firm, non-squishy spacer.
More metric bolts: M4 · M5 · M6 · M8 · M10 · M12 · M16 · M20 — or see the metric conversion guide, Size Finder and size chart.
FAQ
What size rubber washer fits an M3 bolt?
A 1/8" (3.18 mm) inside diameter rubber washer fits a 3 mm M3 bolt with 0.18 mm of clearance — the standard substitution.
What is the smallest rubber washer you stock?
3/16" OD × 3/32" ID × 1/32" thick — sized for miniature fasteners and instrument work.