British Standard Pipe Threads Tap Drill Chart

BSP (British Standard Pipe) is a widely accepted set of screw threads used for connecting and sealing pipes and fittings. The thread form on BSP threads follows the British Standard Whitworth standard. BSP has become the standard in plumbing and pipe fitting worldwide, except in North America where NPT (National Pipe Thread) and similar threads are more common.

BSPP – British Standard Pipe Parallel (Straight)
BSPT – British Standard Pipe Tapered

BSPP & BSPT Tap Drill Chart

Pipe Tap Size BSPP BSPT
Pitch (TPI) Drill Size (inch) Pitch (TPI) Drill Size (inch)
1/16 28 0.261 (G) – –
1/8 28 11/32 28 21/64
1/4 19 29/64 19 7/16
3/8 19 19/32 19 37/64
1/2 14 3/4 14 23/32
5/8 14 53/64 – –
3/4 14 31/32 14 15/16
7/8 14 1-7/64 – –
1 11 1-13/64 11 1-11/64
1-1/4 11 1-35/64 11 1-33/64
1-1/2 11 1-25/32 11 1-3/4
1-3/4 11 2 – –
2 11 2-1/4 11 2-3/16

The values displayed in this table are for direct tapping without reaming.

NPT tap drill chart

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