BSPF (G)
SIZE	THREADS per INCH	TAP DRILL SIZE (mm)
1/8"	28	8.80
1/4"	19	11.80
3/8"	19	15.25
1/2"	14	19.00
5/8"	14	21.00
3/4"	14	24.50
7/8"	14	28.25
1"	11	30.75
1.1/4"	11	39.50
1.1/2"	11	45.00
1.3/4"	11	51.00
2"	11	57.00

BSP PI (Rp)
SIZE	THREADS per INCH	TAP DRILL SIZE (mm)
1/8"	28	8.60
1/4"	19	11.50
3/8"	19	15.00
1/2"	14	18.75
-
3/4"	14	24.25
-
1"	11	30.40
1.1/4"	11	39.00
1.1/2"	11	45.00
-
2"	11	56.75