BSP Pipe Fitting Spanner Sizes — UK Workshop Reference
BSP (British Standard Pipe) fittings are standard across UK and European farm machinery, hydraulics, water systems and compressed air. This chart gives you the correct spanner size, outer diameter and thread count for every BSP size from 1/8" to 3".
What does BSP mean?
BSP stands for British Standard Pipe. It uses parallel (straight) threads — unlike NPT (National Pipe Taper), the American standard, which is tapered. BSP and NPT fittings are not interchangeable even though they can appear to fit at first.
Most common BSP sizes on farm machinery
- 1/4" BSP — 19 mm spanner · hydraulic gauge connections
- 3/8" BSP — 22 mm spanner · small hydraulic lines and unions
- 1/2" BSP — 27 mm spanner · most common on tractor hydraulics
- 3/4" BSP — 32 mm spanner · main hydraulic feeds and return lines
- 1" BSP — 41 mm spanner · large bore hydraulics and water systems
Frequently Asked Questions
- How do I identify BSP size?
- Measure the outer diameter of the male thread (or inner diameter of the female fitting). Match to the OD column above — note the nominal BSP size is NOT the same as the actual thread diameter.
- Can I use BSP fittings with JIC or AN fittings?
- No. BSP, JIC and AN are different thread standards with different profiles. Always use the correct adaptor for your system.
- What spanner do I need for 1/2" BSP?
- A 27 mm spanner fits a standard 1/2" BSP hex fitting.