---
type: "o-ring"
dash_number: "156"
designation: "AS568-156"
cs_series: "102-178"
cs_series_name: "AS568 3/32 in series"
id_in: 4.237
id_mm: 107.62
cs_in: 0.103
cs_mm: 2.62
od_in: 4.443
od_mm: 112.86
id_tol_in: 0.0299
cs_tol_in: 0.0031
standard: "SAE AS568; MIL-G-5514G (public domain, inactive for new design)"
verified: "August 1, 2026"
url: https://shopmath.org/o-rings/as568-156
---

# AS568-156 O-Ring Size — ID, Cross-Section and OD

An AS568-156 o-ring has an inside diameter of 4.2370 in (107.620 mm) and a 0.1030 in (2.620 mm) cross-section, for an outside diameter of 4.4430 in (112.860 mm). It belongs to the AS568 3/32 in series band.

- **Dash number**: 156
- **Cross-section series**: AS568 3/32 in series
- **Inside diameter**: 4.2370 in (107.620 mm)
- **Cross-section**: 0.1030 in (2.620 mm)
- **Outside diameter**: 4.4430 in (112.860 mm)
- **Standard**: SAE AS568; MIL-G-5514G (public domain, inactive for new design)

## AS568-156 Dimensions and Tolerances

| Dimension | Inch | Millimetre |
| --- | --- | --- |
| Inside diameter (ID) | 4.2370 | 107.620 |
| Cross-section (CS) | 0.1030 | 2.620 |
| Outside diameter (OD) | 4.4430 | 112.860 |
| ID tolerance | ±0.0299 | ±0.760 |
| CS tolerance | ±0.0031 | ±0.080 |

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

## Gland Design for AS568-156

Static gland dimensions for the 0.103 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 | 20–30% | 0.0206 – 0.0309 | 0.0721 – 0.0824 | 1.831 – 2.093 |

_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 AS568-156

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) |
| --- | --- | --- | --- | --- |
| [AS568-046](https://shopmath.org/o-rings/as568-046.md) | 4.2390 | 107.670 | 0.0700 | 4.3790 |
| [AS568-244](https://shopmath.org/o-rings/as568-244.md) | 4.2340 | 107.540 | 0.1390 | 4.5120 |
| [AS568-347](https://shopmath.org/o-rings/as568-347.md) | 4.2250 | 107.320 | 0.2100 | 4.6450 |
| [AS568-348](https://shopmath.org/o-rings/as568-348.md) | 4.3500 | 110.490 | 0.2100 | 4.7700 |
| [AS568-245](https://shopmath.org/o-rings/as568-245.md) | 4.3590 | 110.720 | 0.1390 | 4.6370 |
| [AS568-243](https://shopmath.org/o-rings/as568-243.md) | 4.1090 | 104.370 | 0.1390 | 4.3870 |

## Sources and Method for AS568-156

### 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 AS568-156 O-Ring

### What size is an AS568-156 o-ring?

AS568-156 has an inside diameter of 4.2370 in (107.620 mm) and a cross-section of 0.1030 in (2.620 mm), giving an outside diameter of 4.4430 in (112.860 mm).

### What is the o-ring size tolerance on AS568-156?

The AS568 tolerance on AS568-156 is ±0.0299 in (±0.760 mm) on the inside diameter and ±0.0031 in (±0.080 mm) on the cross-section.

### What groove depth does an AS568-156 o-ring need?

For a static face seal, an 0.103 in cross-section needs a gland depth of 0.0721 to 0.0824 in (1.831 to 2.093 mm), which puts the ring at 20–30% squeeze.

### What o-ring is closest in size to AS568-156?

The nearest AS568 sizes by inside diameter are AS568-046 (4.2390 in ID), AS568-244 (4.2340 in ID), AS568-347 (4.2250 in ID).

## Related pages

- Previous dash number: [AS568-155](https://shopmath.org/o-rings/as568-155.md) — 3.9870 in ID
- Next dash number: [AS568-157](https://shopmath.org/o-rings/as568-157.md) — 4.4870 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/as568-156) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*