AS568 Hydraulic O-Ring Size Finder & Nominal Gland Calculator
Find matching standard AS568 dash sizes and Parker size designations from caliper measurements with verified tolerances. Calculate nominal rectangular gland squeeze and area fill without guesswork.
Interactive O-Ring Size Matcher & Gland Calculator
Caliper Measurements
Field Measurement Rule:
Measure without stretching the ring. Close caliper jaws gently onto the elastomer without pinching (rubber deforms 0.1–0.2 mm under light jaw pressure). Used seals with swelling or permanent compression set may not match fresh manufacturing tolerances.
Standard AS568 Candidate Sizes
Awaiting Caliper Measurements
Enter your inside diameter (ID) and cross-section (CS) caliper readings above to find matching AS568 dash size candidates based on official tolerance intervals.
Nominal Rectangular Gland Arithmetic
Nominal Rectangular Gland Arithmetic
Section 4 Model: Calculate nominal squeeze and rectangular groove area fill.
Geometry Assumptions & Assembly Boundary:
H is the assembled sealing gap normal to the squeeze direction (not always raw groove cut depth). Rectangular groove assumed with minimal installed stretch. This arithmetic evaluates cross-sectional geometry only; it does not certify pressure limits, extrusion gaps, corner radii, or thermal swell.
Early Access & Workshop Integration
Eliminate manual searches for hydraulic seal specs
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Curated AS568 & Parker Size Standard Reference
Exact dimensions and tolerance intervals transcribed from Parker ORD 5700 Section IX and SAE AS568 Rev D. Metric equivalents derived via 1 in = 25.4 mm.
| AS568 Dash | Parker Size Desig. | Nominal ID (in / mm) | ID Tol (±) | Nominal CS (in / mm) | CS Tol (±) | Source | Action |
|---|---|---|---|---|---|---|---|
| -001 | 2-001 | 0.029"(0.74 mm) | ±0.004" (±0.10) | 0.040"(1.02 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -002 | 2-002 | 0.042"(1.07 mm) | ±0.004" (±0.10) | 0.050"(1.27 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -003 | 2-003 | 0.056"(1.42 mm) | ±0.004" (±0.10) | 0.060"(1.52 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -004 | 2-004 | 0.070"(1.78 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -005 | 2-005 | 0.101"(2.57 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -006 | 2-006 | 0.114"(2.90 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -007 | 2-007 | 0.145"(3.68 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -008 | 2-008 | 0.176"(4.47 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -009 | 2-009 | 0.208"(5.28 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -010 | 2-010 | 0.239"(6.07 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -011 | 2-011 | 0.301"(7.65 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -012 | 2-012 | 0.364"(9.25 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -013 | 2-013 | 0.426"(10.82 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -014 | 2-014 | 0.489"(12.42 mm) | ±0.005" (±0.13) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -015 | 2-015 | 0.551"(14.00 mm) | ±0.007" (±0.18) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -016 | 2-016 | 0.614"(15.60 mm) | ±0.007" (±0.18) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -018 | 2-018 | 0.739"(18.77 mm) | ±0.007" (±0.18) | 0.070"(1.78 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -110 | 2-110 | 0.362"(9.19 mm) | ±0.005" (±0.13) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -111 | 2-111 | 0.424"(10.77 mm) | ±0.005" (±0.13) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -112 | 2-112 | 0.487"(12.37 mm) | ±0.005" (±0.13) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -113 | 2-113 | 0.549"(13.94 mm) | ±0.007" (±0.18) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -114 | 2-114 | 0.612"(15.54 mm) | ±0.007" (±0.18) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -115 | 2-115 | 0.674"(17.12 mm) | ±0.007" (±0.18) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -116 | 2-116 | 0.737"(18.72 mm) | ±0.007" (±0.18) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -117 | 2-117 | 0.799"(20.29 mm) | ±0.01" (±0.25) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -118 | 2-118 | 0.862"(21.89 mm) | ±0.01" (±0.25) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -120 | 2-120 | 0.987"(25.07 mm) | ±0.01" (±0.25) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -122 | 2-122 | 1.112"(28.24 mm) | ±0.01" (±0.25) | 0.103"(2.62 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -210 | 2-210 | 0.734"(18.64 mm) | ±0.01" (±0.25) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -211 | 2-211 | 0.796"(20.22 mm) | ±0.01" (±0.25) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -212 | 2-212 | 0.859"(21.82 mm) | ±0.01" (±0.25) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -213 | 2-213 | 0.921"(23.39 mm) | ±0.01" (±0.25) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -214 | 2-214 | 0.984"(24.99 mm) | ±0.01" (±0.25) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -215 | 2-215 | 1.046"(26.57 mm) | ±0.01" (±0.25) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -216 | 2-216 | 1.109"(28.17 mm) | ±0.012" (±0.30) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -218 | 2-218 | 1.234"(31.34 mm) | ±0.012" (±0.30) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -220 | 2-220 | 1.359"(34.52 mm) | ±0.012" (±0.30) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -222 | 2-222 | 1.484"(37.69 mm) | ±0.015" (±0.38) | 0.139"(3.53 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -325 | 2-325 | 1.475"(37.47 mm) | ±0.015" (±0.38) | 0.210"(5.33 mm) | ±0.005" (±0.13) | Parker Sec IX | |
| -326 | 2-326 | 1.600"(40.64 mm) | ±0.015" (±0.38) | 0.210"(5.33 mm) | ±0.005" (±0.13) | Parker Sec IX | |
| -327 | 2-327 | 1.725"(43.81 mm) | ±0.015" (±0.38) | 0.210"(5.33 mm) | ±0.005" (±0.13) | Parker Sec IX | |
| -328 | 2-328 | 1.850"(46.99 mm) | ±0.015" (±0.38) | 0.210"(5.33 mm) | ±0.005" (±0.13) | Parker Sec IX | |
| -330 | 2-330 | 2.100"(53.34 mm) | ±0.018" (±0.46) | 0.210"(5.33 mm) | ±0.005" (±0.13) | Parker Sec IX | |
| -425 | 2-425 | 4.475"(113.66 mm) | ±0.03" (±0.76) | 0.275"(6.99 mm) | ±0.006" (±0.15) | Parker Sec IX | |
| -427 | 2-427 | 4.725"(120.01 mm) | ±0.03" (±0.76) | 0.275"(6.99 mm) | ±0.006" (±0.15) | Parker Sec IX | |
| -429 | 2-429 | 4.975"(126.36 mm) | ±0.035" (±0.89) | 0.275"(6.99 mm) | ±0.006" (±0.15) | Parker Sec IX | |
| -901 | 3-901 | 0.185"(4.70 mm) | ±0.005" (±0.13) | 0.056"(1.42 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -902 | 3-902 | 0.239"(6.07 mm) | ±0.005" (±0.13) | 0.064"(1.63 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -903 | 3-903 | 0.301"(7.65 mm) | ±0.005" (±0.13) | 0.064"(1.63 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -904 | 3-904 | 0.351"(8.92 mm) | ±0.005" (±0.13) | 0.072"(1.83 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -905 | 3-905 | 0.414"(10.52 mm) | ±0.005" (±0.13) | 0.072"(1.83 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -906 | 3-906 | 0.468"(11.89 mm) | ±0.005" (±0.13) | 0.078"(1.98 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -908 | 3-908 | 0.644"(16.36 mm) | ±0.009" (±0.23) | 0.087"(2.21 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -910 | 3-910 | 0.811"(20.60 mm) | ±0.01" (±0.25) | 0.097"(2.46 mm) | ±0.003" (±0.08) | Parker Sec IX | |
| -912 | 3-912 | 0.924"(23.47 mm) | ±0.01" (±0.25) | 0.116"(2.95 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -914 | 3-914 | 1.047"(26.59 mm) | ±0.01" (±0.25) | 0.116"(2.95 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -916 | 3-916 | 1.171"(29.74 mm) | ±0.01" (±0.25) | 0.116"(2.95 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -920 | 3-920 | 1.475"(37.47 mm) | ±0.012" (±0.30) | 0.118"(3.00 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -924 | 3-924 | 1.720"(43.69 mm) | ±0.012" (±0.30) | 0.118"(3.00 mm) | ±0.004" (±0.10) | Parker Sec IX | |
| -932 | 3-932 | 2.337"(59.36 mm) | ±0.015" (±0.38) | 0.118"(3.00 mm) | ±0.004" (±0.10) | Parker Sec IX |
Matching Methodology & Engineering Assumptions
Detailed breakdown of measurement intervals, tolerance bounds, and dataset provenance reviewed 30 October 2026.
Two-Dimensional Interval Overlap
Rather than using arbitrary percentage thresholds, candidate matching creates two bounding intervals for both dimensions:
Measurement Interval = [Measurement - Uncertainty, Measurement + Uncertainty]
Specification Interval = [Nominal - Tolerance, Nominal + Tolerance]
A standard size qualifies as a candidate if and only if both the ID interval and CS interval overlap. Arbitrary universal thresholds (like ±0.15 mm) and disproportionate CS weighting have been eliminated.
Ambiguity & Ranking Score
When measurement uncertainty spans adjacent standard sizes, multiple candidates may legitimately overlap. The calculator sorts them by normalized residual sum:
Score = |ΔID| / (ID_Tol + ID_Uncert) + |ΔCS| / (CS_Tol + CS_Uncert)
Sorting is provided purely for browsing convenience. When multiple candidates overlap, neither is mathematically guaranteed to be the exact original seal without checking OEM parts documentation.
Limitations with Field-Sampled Seals
Seals extracted from heavy machinery rarely match brand-new factory tolerances due to two physical degradation mechanisms:
- Compression Set: Prolonged clamping at operating temperatures flattens cross-sections (often reducing CS by 10%–25%).
- Fluid Swelling / Leaching: Chemical incompatibility with hydraulic oils or diesel can expand seal volume or dissolve plasticizers.
Parker Size Codes vs Finished Part Numbers
A designation like 2-115 or 3-908 represents a Parker size designation, not a finished orderable part number and not an OEM cross-reference.
Ordering an actual seal requires specifying the polymer compound (e.g., N0674-70 for standard Nitrile, V0747-75 for fluorocarbon Viton®) and hardness (Durometer Shore A). Size matching alone does not establish oil compatibility or pressure capability.
Hydraulic Seal Material & Compatibility Reference
Educational guide for common hydraulic elastomer compounds. Polymer family names do not represent identical formulations.
NBR / Buna-N (Nitrile)
Standard 70–90 Shore ABest suited for: Petroleum-based mineral hydraulic oils, engine oils, water, and standard grease.
Limitations: Degrades rapidly in high-temperature synthetic diester lubricants, ozone, direct sunlight, and phosphate ester fluids.
FKM / Fluorocarbon (Viton®)
High Temp 75–90 Shore ABest suited for: High-heat hydraulic applications, synthetic transmission fluids, aggressive fuels, and chemical resistance.
Note: Viton® is a registered trademark of The Chemours Company. Not all generic FKM compounds perform identically under extreme dynamic pressures.
EPDM (Ethylene Propylene)
70–80 Shore ABest suited for: Phosphate ester hydraulic fluids (Skydrol), automotive brake fluids (DOT 3/4/5.1), hot water, and steam.
Critical Warning: Never use with mineral or petroleum hydraulic oils; rapid swelling and catastrophic destruction will occur within hours.
High-Pressure Service & Extrusion Resistance Warning:
Finding a matching AS568 dash size does not verify extrusion resistance at high hydraulic pressures (>1,500 psi / 100 bar). In high-pressure cylinder ports, seal hardness (e.g., 90 vs 70 Shore A), diametral clearance (extrusion gap), and hard backup rings (PTFE or hard elastomer) are mandatory engineering parameters governed by manufacturer specifications.