Back to All ToolsSee How
Free Workshop Tool
O-Ring Size Finder
Measure your worn O-ring with calipers, enter any dimension and find the matching standard metric size (DIN 3771 / ISO 3601, CS 1.0–6.0 mm).
Track seal and fitting specs against every asset in your fleet — free.
Enter Your Measurements
Enter any one or two dimensions — the tool finds matching standard sizes. OD = ID + (2 × CS).
Worn or stretched O-rings may measure 10–15% off nominal. Use ±0.5 or ±1.0 for badly degraded seals.
O-Ring Material Guide
Choose the right material — the wrong one will swell, harden or fail under pressure
NBR (Nitrile)
Use for: Hydraulic oil, engine oil, petroleum fuels, compressed air — general fleet & plant use
Avoid: Water/steam systems, brake fluid, ketones and esters
Temp: −40°C to +120°C
EPDM
Use for: Water, steam, detergents, glycol brake fluid, washing systems
Avoid: Petroleum oils, hydraulic fluid, fuels — will swell and fail rapidly
Temp: −40°C to +150°C
Viton (FKM)
Use for: High temp oil, phosphate ester hydraulic fluid, aggressive chemicals, biofuels
Avoid: Steam, hot water — and higher cost, so only where NBR has failed
Temp: −20°C to +200°C
Silicone (VMQ)
Use for: Food grade, extreme temperature static seals
Avoid: Dynamic (moving) seals — tears easily under abrasion
Temp: −60°C to +200°C
Frequently Asked Questions
Track Every Fitting, Spec & Asset in One Place
FleetBolt lets you store key specs against every vehicle and machine, free to get started.
Get Started Free