# Flat washers, inch: SAE and USS, 1/4 to 3/4 in (ASME B18.21.1 Type A)

> What is the difference between SAE and USS washers?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: ASME B18.21.1 Type A plain washers, narrow (SAE) and wide (USS): ID, OD, thickness (nominal)
- Page: https://xemstudio.com/objects/flat-washers-inch/ · JSON: https://xemstudio.com/api/geometry?object=flat-washers-inch · Plain text: https://xemstudio.com/objects/flat-washers-inch/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- SAE washers are narrow (fit under socket heads and in tight spots); USS are wide (spread load on wood and soft material).

## Sizes

| size | type | id_in | od_in | thickness_in |
|---|---|---|---|---|
| 1/4 | USS | 0.312 | 0.734 | 0.065 |
| 1/4 | SAE | 0.281 | 0.625 | 0.065 |
| 5/16 | USS | 0.375 | 0.875 | 0.083 |
| 5/16 | SAE | 0.344 | 0.688 | 0.065 |
| 3/8 | USS | 0.438 | 1.0 | 0.083 |
| 3/8 | SAE | 0.406 | 0.812 | 0.065 |
| 7/16 | USS | 0.5 | 1.25 | 0.083 |
| 7/16 | SAE | 0.469 | 0.922 | 0.065 |
| 1/2 | USS | 0.562 | 1.375 | 0.109 |
| 1/2 | SAE | 0.531 | 1.062 | 0.095 |
| 5/8 | USS | 0.688 | 1.75 | 0.134 |
| 5/8 | SAE | 0.656 | 1.312 | 0.095 |
| 3/4 | USS | 0.812 | 2.0 | 0.148 |
| 3/4 | SAE | 0.812 | 1.469 | 0.134 |

## Where the files are

- ASME: [ASME B18.21.1 Washers: helical spring-lock, tooth lock, and plain washers (inch)](https://www.asme.org/codes-standards/find-codes-standards/b18-21-1-washers-helical-spring-lock-tooth-lock-plain-washers-(inch-series)) — standard — ASME; dimensions are facts (verify at link)

## Free STEP/STL (14 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/flat-washers-inch/index.json

- washer-uss-1-4-20: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-1-4-20.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-1-4-20.stl) — 1/4 in USS flat washer: 0.312 × 0.734 × 0.065 in
- washer-sae-1-4-20: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-1-4-20.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-1-4-20.stl) — 1/4 in SAE flat washer: 0.281 × 0.625 × 0.065 in
- washer-uss-5-16-18: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-5-16-18.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-5-16-18.stl) — 5/16 in USS flat washer: 0.375 × 0.875 × 0.083 in
- washer-sae-5-16-18: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-5-16-18.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-5-16-18.stl) — 5/16 in SAE flat washer: 0.344 × 0.688 × 0.065 in
- washer-uss-3-8-16: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-3-8-16.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-3-8-16.stl) — 3/8 in USS flat washer: 0.438 × 1.000 × 0.083 in
- washer-sae-3-8-16: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-3-8-16.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-3-8-16.stl) — 3/8 in SAE flat washer: 0.406 × 0.812 × 0.065 in
- washer-uss-7-16-14: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-7-16-14.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-7-16-14.stl) — 7/16 in USS flat washer: 0.500 × 1.250 × 0.083 in
- washer-sae-7-16-14: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-7-16-14.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-7-16-14.stl) — 7/16 in SAE flat washer: 0.469 × 0.922 × 0.065 in
- washer-uss-1-2-13: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-1-2-13.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-1-2-13.stl) — 1/2 in USS flat washer: 0.562 × 1.375 × 0.109 in
- washer-sae-1-2-13: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-1-2-13.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-1-2-13.stl) — 1/2 in SAE flat washer: 0.531 × 1.062 × 0.095 in
- washer-uss-5-8-11: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-5-8-11.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-5-8-11.stl) — 5/8 in USS flat washer: 0.688 × 1.750 × 0.134 in
- washer-sae-5-8-11: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-5-8-11.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-5-8-11.stl) — 5/8 in SAE flat washer: 0.656 × 1.312 × 0.095 in
- washer-uss-3-4-10: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-3-4-10.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-uss-3-4-10.stl) — 3/4 in USS flat washer: 0.812 × 2.000 × 0.148 in
- washer-sae-3-4-10: [STEP](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-3-4-10.step) · [STL](https://xemstudio.com/files/hardware/flat-washers-inch/washer-sae-3-4-10.stl) — 3/4 in SAE flat washer: 0.812 × 1.469 × 0.134 in

## Questions

**SAE or USS?**

SAE for metal and tight spaces, USS for wood and soft material.

## Fits with

- [Hex bolts, inch: 1/4-20 to 3/4-10 (ASME B18.2.1)](https://xemstudio.com/objects/hex-bolts-inch/)
- [Hex nuts, inch: #4-40 to 3/4-10 (ASME B18.2.2)](https://xemstudio.com/objects/hex-nuts-inch/)
- [Socket head cap screws, inch: #10-24, #10-32, 5/16-18, 3/8-16, 1/2-13 (ASME B18.3)](https://xemstudio.com/objects/socket-head-cap-screws-inch/)
- [Button head socket cap screws, inch: #4-40 to 1/2-13 (ASME B18.3)](https://xemstudio.com/objects/button-head-socket-screws-inch/)
- [Imperial machine screws: #4-40, #6-32, #8-32, 1/4-20](https://xemstudio.com/objects/imperial-machine-screws/)