---
type: "o-ring"
dash_number: "259"
designation: "AS568-259"
cs_series: "201-284"
cs_series_name: "AS568 1/8 in series"
id_in: 6.234
id_mm: 158.34
cs_in: 0.139
cs_mm: 3.53
od_in: 6.512
od_mm: 165.4
id_tol_in: 0.0402
cs_tol_in: 0.0039
standard: "SAE AS568; MIL-G-5514G (public domain, inactive for new design)"
verified: "August 1, 2026"
url: https://shopmath.org/o-rings/as568-259
---

# AS568-259 O-Ring Size — ID, Cross-Section and OD

An AS568-259 o-ring has an inside diameter of 6.2340 in (158.340 mm) and a 0.1390 in (3.530 mm) cross-section, for an outside diameter of 6.5120 in (165.400 mm). It belongs to the AS568 1/8 in series band.

- **Dash number**: 259
- **Cross-section series**: AS568 1/8 in series
- **Inside diameter**: 6.2340 in (158.340 mm)
- **Cross-section**: 0.1390 in (3.530 mm)
- **Outside diameter**: 6.5120 in (165.400 mm)
- **Standard**: SAE AS568; MIL-G-5514G (public domain, inactive for new design)

## AS568-259 Dimensions and Tolerances

| Dimension | Inch | Millimetre |
| --- | --- | --- |
| Inside diameter (ID) | 6.2340 | 158.340 |
| Cross-section (CS) | 0.1390 | 3.530 |
| Outside diameter (OD) | 6.5120 | 165.400 |
| ID tolerance | ±0.0402 | ±1.020 |
| CS tolerance | ±0.0039 | ±0.100 |

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

## Gland Design for AS568-259

Static gland dimensions for the 0.139 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% | 0.0278 – 0.0417 | 0.0973 – 0.1112 | 2.471 – 2.824 |

_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 AS568-259

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) |
| --- | --- | --- | --- | --- |
| [AS568-164](https://shopmath.org/o-rings/as568-164.md) | 6.2370 | 158.420 | 0.1030 | 6.4430 |
| [AS568-362](https://shopmath.org/o-rings/as568-362.md) | 6.2250 | 158.120 | 0.2100 | 6.6450 |
| [AS568-438](https://shopmath.org/o-rings/as568-438.md) | 6.2250 | 158.120 | 0.2750 | 6.7750 |
| [AS568-363](https://shopmath.org/o-rings/as568-363.md) | 6.4750 | 164.470 | 0.2100 | 6.8950 |
| [AS568-439](https://shopmath.org/o-rings/as568-439.md) | 6.4750 | 164.470 | 0.2750 | 7.0250 |
| [AS568-163](https://shopmath.org/o-rings/as568-163.md) | 5.9870 | 152.070 | 0.1030 | 6.1930 |

## Sources and Method for AS568-259

### 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 AS568-259 O-Ring

### What size is an AS568-259 o-ring?

AS568-259 has an inside diameter of 6.2340 in (158.340 mm) and a cross-section of 0.1390 in (3.530 mm), giving an outside diameter of 6.5120 in (165.400 mm).

### What is the o-ring size tolerance on AS568-259?

The AS568 tolerance on AS568-259 is ±0.0402 in (±1.020 mm) on the inside diameter and ±0.0039 in (±0.100 mm) on the cross-section.

### What groove depth does an AS568-259 o-ring need?

For a static face seal, an 0.139 in cross-section needs a gland depth of 0.0973 to 0.1112 in (2.471 to 2.824 mm), which puts the ring at 20–30% squeeze.

### What o-ring is closest in size to AS568-259?

The nearest AS568 sizes by inside diameter are AS568-164 (6.2370 in ID), AS568-362 (6.2250 in ID), AS568-438 (6.2250 in ID).

## Related pages

- Previous dash number: [AS568-258](https://shopmath.org/o-rings/as568-258.md) — 5.9840 in ID
- Next dash number: [AS568-260](https://shopmath.org/o-rings/as568-260.md) — 6.4840 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/as568-259) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*