---
type: "o-ring"
dash_number: "370"
designation: "AS568-370"
cs_series: "309-395"
cs_series_name: "AS568 3/16 in series"
id_in: 8.225
id_mm: 208.92
cs_in: 0.21
cs_mm: 5.33
od_in: 8.645
od_mm: 219.58
id_tol_in: 0.05
cs_tol_in: 0.0051
standard: "SAE AS568; MIL-G-5514G (public domain, inactive for new design)"
verified: "August 1, 2026"
url: https://shopmath.org/o-rings/as568-370
---

# AS568-370 O-Ring Size — ID, Cross-Section and OD

An AS568-370 o-ring has an inside diameter of 8.2250 in (208.920 mm) and a 0.2100 in (5.330 mm) cross-section, for an outside diameter of 8.6450 in (219.580 mm). It belongs to the AS568 3/16 in series band.

- **Dash number**: 370
- **Cross-section series**: AS568 3/16 in series
- **Inside diameter**: 8.2250 in (208.920 mm)
- **Cross-section**: 0.2100 in (5.330 mm)
- **Outside diameter**: 8.6450 in (219.580 mm)
- **Standard**: SAE AS568; MIL-G-5514G (public domain, inactive for new design)

## AS568-370 Dimensions and Tolerances

| Dimension | Inch | Millimetre |
| --- | --- | --- |
| Inside diameter (ID) | 8.2250 | 208.920 |
| Cross-section (CS) | 0.2100 | 5.330 |
| Outside diameter (OD) | 8.6450 | 219.580 |
| ID tolerance | ±0.0500 | ±1.270 |
| CS tolerance | ±0.0051 | ±0.130 |

_Outside diameter is computed as ID + 2 × CS; AS568 tabulates ID and CS._

## Gland Design for AS568-370

Static gland dimensions for the 0.210 in cross-section. Depth is the groove depth that produces the stated squeeze on a nominal ring.

| Application | Squeeze | Squeeze (in) | Gland depth (in) | Gland depth (mm) |
| --- | --- | --- | --- | --- |
| Static face seal | 21–30% | 0.0441 – 0.0630 | 0.1470 – 0.1659 | 3.734 – 4.214 |

_Gland depth is computed as CS − (CS × squeeze %), then checked against the published design charts. Groove width, corner radius and back-up ring allowances are outside this dataset._

## O-Ring Sizes Closest to AS568-370

Nearest AS568 sizes by inside diameter — the substitutes to check when this one is out of stock.

| Size | ID (in) | ID (mm) | CS (in) | OD (in) |
| --- | --- | --- | --- | --- |
| [AS568-267](https://shopmath.org/o-rings/as568-267.md) | 8.2340 | 209.140 | 0.1390 | 8.5120 |
| [AS568-172](https://shopmath.org/o-rings/as568-172.md) | 8.2370 | 209.220 | 0.1030 | 8.4430 |
| [AS568-171](https://shopmath.org/o-rings/as568-171.md) | 7.9870 | 202.870 | 0.1030 | 8.1930 |
| [AS568-266](https://shopmath.org/o-rings/as568-266.md) | 7.9840 | 202.790 | 0.1390 | 8.2620 |
| [AS568-369](https://shopmath.org/o-rings/as568-369.md) | 7.9750 | 202.570 | 0.2100 | 8.3950 |
| [AS568-445](https://shopmath.org/o-rings/as568-445.md) | 7.9750 | 202.570 | 0.2750 | 8.5250 |

## Sources and Method for AS568-370

### AS568 dimensions

- **Source**: bd_warehouse o-ring_parameters.csv (Apache-2.0) and bckasper3/KasperCalc oring-sizes.js (MIT), agreeing on all 349 sizes; OD computed as ID + 2 x CS
- **Method**: computed+compiled
- **Verified against**: two independent open datasets agreeing on all 349 sizes; fabricated-dataset negative control passed; 21 checks total

### Gland design

- **Source**: MIL-G-5514G (public domain) gland design criteria; squeeze-percentage bands cross-read from Parker O-Ring Handbook ORD-5700 Design Charts 4-2/4-3 (verification only); depth = CS - CS x squeeze%
- **Method**: computed
- **Verified against**: computed depth band brackets the published design-chart band for every series

### Assumptions

- Dimensions are for a nominal, unstretched ring at room temperature. Installed stretch reduces cross-section.
- Gland figures are static-application only and assume a nominal ring; they carry no compound, temperature or pressure assumption.
- Dataset scope: A fabricated-dataset negative control is asserted against on every run. EXCLUDED: groove width, corner radius, diametral clearance, back-up ring widths, surface finish, all dynamic glands, the 900-series, and ISO 3601 metric sizes.

**Data last verified**: August 1, 2026

## Common Questions About the AS568-370 O-Ring

### What size is an AS568-370 o-ring?

AS568-370 has an inside diameter of 8.2250 in (208.920 mm) and a cross-section of 0.2100 in (5.330 mm), giving an outside diameter of 8.6450 in (219.580 mm).

### What is the o-ring size tolerance on AS568-370?

The AS568 tolerance on AS568-370 is ±0.0500 in (±1.270 mm) on the inside diameter and ±0.0051 in (±0.130 mm) on the cross-section.

### What groove depth does an AS568-370 o-ring need?

For a static face seal, an 0.210 in cross-section needs a gland depth of 0.1470 to 0.1659 in (3.734 to 4.214 mm), which puts the ring at 21–30% squeeze.

### What o-ring is closest in size to AS568-370?

The nearest AS568 sizes by inside diameter are AS568-267 (8.2340 in ID), AS568-172 (8.2370 in ID), AS568-171 (7.9870 in ID).

## Related pages

- Previous dash number: [AS568-369](https://shopmath.org/o-rings/as568-369.md) — 7.9750 in ID
- Next dash number: [AS568-371](https://shopmath.org/o-rings/as568-371.md) — 8.4750 in ID
- All o-ring sizes: [AS568 o-ring reference](https://shopmath.org/o-rings.md)
- Full size chart: [AS568 o-ring size chart](https://shopmath.org/charts/o-ring-sizes.md)

---

*Source: [ShopMath](https://shopmath.org/o-rings/as568-370) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*