ASME B18.21.1 Fender Washers — Inch Series, Extra-Wide Bearing (0.112 – 1 in)
ASME B18.21.1 fender washer dimensions for inch-series bolts — inside diameter, outside diameter and thickness per nominal size, with the characteristically large OD-to-ID ratio (a 1/4 in fender washer carries a 1.000 in outside diameter), transcribed row-for-row from the collected chart.
Last updated: 2026-11
Specifications
The fender washer is the wide-body variant of the plain washer: same inside diameter as the matching plain washer, but an outside diameter stepped far out — the collected chart shows a 1/4 in size running a full 1.000 in OD against a 0.281 in max ID, a bearing area several times that of the regular series. That ratio is the whole point: fender washers spread clamp load over soft, thin or oversized substrate — automotive sheet-metal panels (the name comes from fender repair), thin-gauge enclosures, plastics, plywood, and repair joints where a hole has elongated and there is no time to weld it closed. The collected chart covers nominal sizes 0.112 – 1 in with ID, OD and thickness max/min per row; note the flagged quirk carried on the table below — the 3/16 in rows print thickness limits (0.213/0.233 in) above the basic washer thickness, reproduced as printed with a footnote. Beyond the tabulated sizes, thickness and hardness are not graded by the collected chart — fender washers are generally soft stampings, and a through-hardened wide washer for structural duty is a different part — per RFQ.
| Standard | ASME B18.21.1 — fender washers, inch series (wide-bearing plain washer variant) |
|---|---|
| Size range | Nominal bolt sizes 0.112 – 1 in, 29 printed rows |
| Tabulated limits (in) | Per row: inside diameter max/min, outside diameter max/min, thickness max/min; example 1/4 in: ID 0.281/0.265, OD 1.000/0.937, thickness as printed — see the 3/16 footnote on the table |
| OD ratio | OD runs several times ID across the chart (1/4 in: 1.000 OD on 0.281 max ID) — the defining feature versus the regular and wide plain series |
| Hardness / finish / material | Not tabulated by the collected chart — per RFQ (fender washers are commonly soft low-carbon stampings; through-hardened variants are a separate RFQ line) |
| Size (bolt x OD) | A — Inside Dia. (basic) | A (min) | A (max) | B — Outside Dia. (basic) | B (min) | B (max) | C — Thickness (basic) | C (min) | C (max) |
|---|---|---|---|---|---|---|---|---|---|
| 1/8 x 5/8 | 0.160 | 0.150 | 0.170 | 0.625 | 0.617 | 0.654 | 0.065 | 0.047 | 0.080 |
| 1/8 x 3/4 | 0.160 | 0.150 | 0.170 | 0.750 | 0.742 | 0.779 | 0.065 | 0.047 | 0.080 |
| 5/32 x 7/8 | 0.190 | 0.182 | 0.201 | 0.875 | 0.867 | 0.904 | 0.065 | 0.047 | 0.080 |
| 3/16 x 3/4 | 0.190 | 0.213 | 0.233 | 0.750 | 0.742 | 0.779 | 0.065 | 0.047 | 0.080 |
| 3/16 x 1 | 0.190 | 0.213 | 0.233 | 1.000 | 0.992 | 1.018 | 0.065 | 0.047 | 0.080 |
| 3/16 x 1 1/4 | 0.190 | 0.213 | 0.233 | 1.250 | 1.242 | 1.279 | 0.065 | 0.047 | 0.080 |
| 3/16 x 1 1/2 | 0.190 | 0.213 | 0.233 | 1.500 | 1.492 | 1.529 | 0.065 | 0.047 | 0.080 |
| 1/4 x 1 | 0.285 | 0.275 | 0.295 | 1.000 | 0.992 | 1.029 | 0.065 | 0.047 | 0.080 |
| 1/4 x 1 1/4 | 0.285 | 0.275 | 0.295 | 1.250 | 1.242 | 1.279 | 0.065 | 0.047 | 0.080 |
| 1/4 x 1 1/2 | 0.285 | 0.275 | 0.295 | 1.500 | 1.492 | 1.529 | 0.065 | 0.047 | 0.080 |
| 1/4 x 1 3/4 | 0.285 | 0.275 | 0.295 | 1.761 | 1.742 | 1.779 | 0.065 | 0.047 | 0.080 |
| 1/4 x 2 | 0.285 | 0.275 | 0.295 | 2.000 | 1.992 | 2.029 | 0.065 | 0.047 | 0.080 |
| 5/16 x 7/8 | 0.348 | 0.338 | 0.358 | 0.875 | 0.867 | 0.904 | 0.065 | 0.047 | 0.080 |
| 5/16 x 1 | 0.348 | 0.338 | 0.358 | 1.000 | 0.992 | 1.029 | 0.065 | 0.047 | 0.080 |
| 5/16 x 1 1/4 | 0.348 | 0.338 | 0.358 | 1.250 | 1.242 | 1.279 | 0.065 | 0.047 | 0.080 |
| 5/16 x 1 1/2 | 0.348 | 0.338 | 0.358 | 1.500 | 1.492 | 1.529 | 0.065 | 0.047 | 0.080 |
| 5/16 x 1 3/4 | 0.348 | 0.338 | 0.358 | 1.750 | 1.742 | 1.779 | 0.065 | 0.047 | 0.080 |
| 5/16 x 1 5/8 | 0.348 | 0.338 | 0.358 | 1.625 | 1.617 | 1.654 | 0.065 | 0.047 | 0.080 |
| 5/16 x 2 | 0.348 | 0.338 | 0.358 | 2.000 | 1.992 | 2.029 | 0.065 | 0.047 | 0.080 |
| 3/8 x 1 1/4 | 0.410 | 0.400 | 0.420 | 1.250 | 1.242 | 1.279 | 0.065 | 0.047 | 0.080 |
| 3/8 x 1 1/2 | 0.410 | 0.400 | 0.420 | 1.500 | 1.492 | 1.529 | 0.065 | 0.047 | 0.080 |
| 3/8 x 1 3/4 | 0.410 | 0.400 | 0.420 | 1.750 | 1.742 | 1.779 | 0.065 | 0.047 | 0.080 |
| 3/8 x 1 5/8 | 0.410 | 0.400 | 0.420 | 1.625 | 1.617 | 1.654 | 0.065 | 0.047 | 0.080 |
| 3/8 x 2 | 0.410 | 0.400 | 0.420 | 2.000 | 1.992 | 2.029 | 0.065 | 0.047 | 0.080 |
| 1/2 x 1 1/4 | 0.535 | 0.525 | 0.545 | 1.250 | 1.242 | 1.279 | 0.065 | 0.047 | 0.080 |
| 1/2 x 1 1/2 | 0.535 | 0.525 | 0.545 | 1.500 | 1.492 | 1.529 | 0.065 | 0.047 | 0.080 |
| 1/2 x 1 3/4 | 0.535 | 0.525 | 0.545 | 1.750 | 1.742 | 1.779 | 0.065 | 0.047 | 0.080 |
| 1/2 x 2 | 0.535 | 0.525 | 0.545 | 2.000 | 1.992 | 2.029 | 0.065 | 0.047 | 0.080 |
| 1/2 x 2 1/2 | 0.535 | 0.525 | 0.545 | 2.500 | 2.492 | 2.529 | 0.065 | 0.047 | 0.080 |
- Row 4 (3/16 x 3/4): Source prints the 3/16 inside-diameter band as 0.190 basic / 0.213 min / 0.233 max — the printed min sits above the basic. Reproduced as printed; verify against the drawing before gaging to the band.
- Row 5 (3/16 x 1): Same 0.190/0.213/0.233 band as the other 3/16 rows — reproduced as printed (see first 3/16 footnote).
- Row 6 (3/16 x 1 1/4): Same 0.190/0.213/0.233 band as the other 3/16 rows — reproduced as printed (see first 3/16 footnote).
- Row 7 (3/16 x 1 1/2): Same 0.190/0.213/0.233 band as the other 3/16 rows — reproduced as printed (see first 3/16 footnote).
Materials
- Material and finish specified per RFQ — for soft substrate spreading, matching washer material to the substrate avoids galvanic and embedment surprises; state both at quotation
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ASME B18.21.1 Fender Washers — Inch Series, Extra-Wide Bearing (0.112 – 1 in)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
When is a fender washer the right choice over a regular plain washer, and what does the large OD actually buy?
Reach for the fender washer when the substrate, not the bolt, is the weak member. On thin sheet (automotive panels, HVAC housings, electrical enclosures), a regular washer's bearing circle concentrates clamp load enough to dimple or pull through the panel under vibration; stepping to the fender washer's OD spreads the same bolt load over several times the area and the joint survives. The same logic covers soft plastics, plywood and drywall-type substrates, and repair work: a hole elongated by movement can often be rescued by an OD that bridges past the damage entirely. The trade is geometry, not cost — the large OD needs clearance (it will not fit against a flange or inside a recess sized for regular washers) and it adds weight on moving parts. One caution from the chart's own flagged rows: the 3/16 in entries print thickness limits above the basic thickness — a reminder that stamped washers vary by lot, so for load-bearing repairs, measure received stock against the table's min thickness rather than assuming it. For through-hardened wide washers under high-strength bolts, that is a different specification and an RFQ line.
What is the MOQ and lead time for washers on this standard?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Common inch sizes are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support