Reverse Lookup

Instructions

This table is intended to facilitate finding the name, or type, of a thread form when that information is not known. This might typically happen when one has a screw that needs to be matched, but this table can also be used to help choose between similar thread forms.

On the left hand side of the page the outside diameter of the thread is given, along with the pitch. The table is sorted, diameter and then pitch. Inch and metric equivalents are given. If you have a screw and you need to find out what it is, first measure the outside diameter (inch or metric), and find similar entries in the first columns. Then, if necassary, measure the pitch of the screw to differentiate between the screw thread families. In some cases similar threads from different families will match in both diameter and pitch, but have a different thread angle. Each family has it’s own column, and the descriptive indexes in these columns are clickable to take you to the full thread data for that particular screw thread.

Reverse lookup tables

Nominal Diameter		Pitch		Metric Coarse	Metric Fine	Metric Special	UNF	UNC	BA	BSF	BSB	BSC	Whit	ME
(inch)	(mm)	(inch)	(mm)	(n/a)	(n/a)	(n/a)	(n/a)	(n/a)	(n/a)	(n/a)	(n/a)	(n/a)	(n/a)	(n/a)
0.0311	0.79	0.0075	0.19						16BA
0.0354	0.90	0.0083	0.21						15BA
0.0394	1.00	0.0098	0.25	M1
0.0394	1.00	0.0091	0.23						14BA
0.0433	1.10	0.0098	0.25	M1.1
0.0472	1.20	0.0098	0.25						13BA
0.0472	1.20	0.0098	0.25	M1.2
0.0512	1.30	0.0110	0.28						12BA
0.0551	1.40	0.0118	0.30	M1.4
0.0591	1.50	0.0122	0.31						11BA
0.0600	1.52	0.0125	0.32				No. 0 UNF
0.0625	1.59	0.0167	0.42										1/16 WHIT
0.0630	1.60	0.0138	0.35	M1.6
0.0669	1.70	0.0138	0.35						10BA
0.0669	1.70	0.0138	0.35			M1.7(S)
0.0709	1.80	0.0138	0.35	M1.8
0.0730	1.85	0.0139	0.35				No. 1 UNF
0.0730	1.85	0.0156	0.40					No. 1 UNC
0.0748	1.90	0.0154	0.39						9BA
0.0787	2.00	0.0157	0.40	M2
0.0787	2.00	0.0177	0.45			M2(S)
0.0860	2.18	0.0156	0.40				No. 2 UNF
0.0860	2.18	0.0179	0.45					No.2 UNC
0.0866	2.20	0.0169	0.43						8BA
0.0866	2.20	0.0177	0.45	M2.2
0.0906	2.30	0.0157	0.40			M2.3(S)
0.0938	2.38	0.0208	0.53										3/32 WHIT
0.0984	2.50	0.0189	0.48						7BA
0.0984	2.50	0.0177	0.45	M2.5
0.0990	2.51	0.0179	0.45				No. 3 UNF
0.0990	2.51	0.0208	0.53					No. 3 UNC
0.1024	2.60	0.0177	0.45			M2.6(S)
0.1102	2.80	0.0209	0.53						6BA
0.1120	2.84	0.0208	0.53				No. 4 UNF
0.1120	2.84	0.0250	0.64					No.4 UNC
0.1181	3.00	0.0138	0.35		M3(F)
0.1181	3.00	0.0197	0.50	M3
0.1181	3.00	0.0236	0.60			M3(S)
0.1250	3.18	0.0227	0.58				No. 5 UNF
0.1250	3.18	0.0250	0.64										1/8 WHIT
0.1250	3.18	0.0250	0.64					No. 5 UNC
0.1250	3.18	0.0250	0.64											1/8 ME
0.1250	3.18	0.0250	0.64									1/8 BSC
0.1250	3.18	0.0385	0.98								1/8 BSB
0.1260	3.20	0.0232	0.59						5BA
0.1378	3.50	0.0236	0.60	M3.5
0.1380	3.51	0.0250	0.64				No. 6 UNF
0.1380	3.51	0.0313	0.79					No.6 UNC
0.1417	3.60	0.0260	0.66						4BA
0.1562	3.97	0.0313	0.79										5/32 WHIT
0.1563	3.97	0.0250	0.64											5/32 ME
0.1563	3.97	0.0313	0.79									5/32 BSC
0.1575	4.00	0.0197	0.50		M4(F)
0.1575	4.00	0.0276	0.70	M4
0.1575	4.00	0.0295	0.75			M4(S)
0.1614	4.10	0.0287	0.73						3BA
0.1640	4.17	0.0278	0.71				No. 8 UNF
0.1640	4.17	0.0313	0.79					No 8 UNC
0.1772	4.50	0.0295	0.75	M4.5
0.1850	4.70	0.0319	0.81						2BA
0.1875	4.76	0.0250	0.64											3/16 ME
0.1875	4.76	0.0313	0.79									3/16 BSC
0.1875	4.76	0.0313	0.79							3/16 BSF
0.1875	4.76	0.0417	1.06										3/16 WHIT
0.1900	4.83	0.0313	0.79				No. 10 UNF
0.1900	4.83	0.0417	1.06					No. 10 UNC
0.1969	5.00	0.0197	0.50		M5(F)
0.1969	5.00	0.0315	0.80	M5
0.1969	5.00	0.0354	0.90			M5(S)
0.2087	5.30	0.0354	0.90						1BA
0.2160	5.49	0.0357	0.91				No. 12 UNF
0.2160	5.49	0.0417	1.06					No. 12 UNC
0.2165	5.50	0.0354	0.90			M5.5(S)
0.2188	5.56	0.0250	0.64											7/32 ME
0.2188	5.56	0.0357	0.91							7/32 BSF
0.2188	5.56	0.0417	1.06										7/32 WHIT
0.2362	6.00	0.0394	1.00						0BA
0.2362	6.00	0.0295	0.75		M6(F)
0.2362	6.00	0.0394	1.00	M6
0.2500	6.35	0.0250	0.64											1/4 ME
0.2500	6.35	0.0357	0.91				1/4 UNF
0.2500	6.35	0.0385	0.98									1/4 BSC
0.2500	6.35	0.0385	0.98								1/4 BSB
0.2500	6.35	0.0385	0.98							1/4 BSF
0.2500	6.35	0.0500	1.27										1/4 WHIT
0.2500	6.35	0.0500	1.27					1/4 UNC
0.2756	7.00	0.0295	0.75		M7(F)
0.2756	7.00	0.0394	1.00	M7
0.2810	7.14	0.0385	0.98									9/32 BSC
0.2813	7.14	0.0313	0.79											9/32 ME
0.3125	7.94	0.0313	0.79											5/16 ME
0.3125	7.94	0.0385	0.98									5/16 BSC
0.3125	7.94	0.0417	1.06				5/16 UNF
0.3125	7.94	0.0455	1.15							5/16 BSF
0.3125	7.94	0.0556	1.41										5/16 WHIT
0.3125	7.94	0.0556	1.41					5/16 UNC
0.3150	8.00	0.0295	0.75			M8(S)
0.3150	8.00	0.0394	1.00		M8(F)
0.3150	8.00	0.0492	1.25	M8
0.3543	9.00	0.0394	1.00			M9(S)
0.3543	9.00	0.0492	1.25	M9
0.3750	9.53	0.0313	0.79											3/8 ME
0.3750	9.53	0.0385	0.98									3/8 BSC
0.3750	9.53	0.0385	0.98								3/8 BSB
0.3750	9.53	0.0417	1.06				3/8 UNF
0.3750	9.53	0.0500	1.27							3/8 BSF
0.3750	9.53	0.0625	1.59										3/8 WHIT
0.3750	9.53	0.0625	1.59					3/8 UNC
0.3937	10.00	0.0295	0.75			M10(S)
0.3937	10.00	0.0394	1.00			M10(S)
0.3937	10.00	0.0492	1.25		M10(F)
0.3937	10.00	0.0591	1.50	M10
0.4331	11.00	0.0591	1.50	M11
0.4375	11.11	0.0385	0.98									7/16 BSC
0.4375	11.11	0.0500	1.27				7/16 UNF
0.4375	11.11	0.0556	1.41							7/16 BSF
0.4375	11.11	0.0714	1.81										7/16 WHIT
0.4375	11.11	0.0714	1.81					7/16 UNC
0.4724	12.00	0.0394	1.00			M12(S)
0.4724	12.00	0.0492	1.25		M12(F)
0.4724	12.00	0.0591	1.50			M12(S)
0.4724	12.00	0.0689	1.75	M12
0.5000	12.70	0.0385	0.98									1/2 BSC
0.5000	12.70	0.0385	0.98								1/2 BSB
0.5000	12.70	0.0500	1.27				1/2 UNF
0.5000	12.70	0.0625	1.59							1/2 BSF
0.5000	12.70	0.0769	1.95					1/2 UNC
0.5000	12.70	0.0833	2.12										1/2 WHIT
0.5512	14.00	0.0492	1.25			M14(S)
0.5512	14.00	0.0591	1.50		M14(F)
0.5512	14.00	0.0787	2.00	M14
0.5625	14.29	0.0385	0.98									9/16 BSC
0.5625	14.29	0.0556	1.41				9/16 UNF
0.5625	14.29	0.0625	1.59							9/16 BSF
0.5625	14.29	0.0833	2.12										9/16 WHIT
0.5625	14.29	0.0833	2.12					9/16 UNC
0.6250	15.88	0.0385	0.98									5/8 BSC
0.6250	15.88	0.0385	0.98								5/8 BSB
0.6250	15.88	0.0556	1.41				5/8 UNF
0.6250	15.88	0.0714	1.81							5/8 BSF
0.6250	15.88	0.0909	2.31										5/8 WHIT
0.6250	15.88	0.0909	2.31					5/8 UNC
0.6299	16.00	0.0394	1.00			M16(S)
0.6299	16.00	0.0591	1.50		M16(F)
0.6299	16.00	0.0787	2.00	M16
0.6875	17.46	0.0385	0.98									11/16 BSC
0.6875	17.46	0.0714	1.81							11/16 BSF
0.6875	17.46	0.0909	2.31										11/16 WHIT
0.7087	18.00	0.0591	1.50		M18(F)
0.7087	18.00	0.0984	2.50	M18
0.7500	19.05	0.0385	0.98								3/4 BSB
0.7500	19.05	0.0625	1.59				3/4 UNF
0.7500	19.05	0.0833	2.12							3/4 BSF
0.7500	19.05	0.1000	2.54										3/4 WHIT
0.7500	19.05	0.1000	2.54					3/4 UNC
0.7874	20.00	0.0394	1.00			M20(S)
0.7874	20.00	0.0591	1.50		M20(F)
0.7874	20.00	0.0787	2.00			M20(S)
0.7874	20.00	0.0984	2.50	M20
0.8125	20.64	0.1000	2.54										13/16 WHIT
0.8661	22.00	0.0591	1.50		M22(F)
0.8661	22.00	0.0984	2.50	M22
0.8750	22.23	0.0385	0.98								7/8 BSB
0.8750	22.23	0.0714	1.81				7/8 UNF
0.8750	22.23	0.0909	2.31							7/8 BSF
0.8750	22.23	0.1111	2.82										7/8 WHIT
0.8750	22.23	0.1111	2.82					7/8 UNC
0.9375	23.81	0.1111	2.82										15/16 WHIT
0.9449	24.00	0.0394	1.00			M24(S)
0.9449	24.00	0.0591	1.50			M24(S)
0.9449	24.00	0.0787	2.00		M24(F)
0.9449	24.00	0.1181	3.00	M24
0.9843	25.00	0.0591	1.50			M25(S)
1.0000	25.40	0.0385	0.98									1 BSC
1.0000	25.40	0.0385	0.98								1 BSB
1.0000	25.40	0.0833	2.12				1 UNF
1.0000	25.40	0.1000	2.54							1 BSF
1.0000	25.40	0.1250	3.18										1, WHIT
1.0000	25.40	0.1250	3.18					1 UNC
1.0630	27.00	0.0787	2.00		M27(F)
1.0630	27.00	0.1181	3.00	M27
1.1250	28.58	0.0385	0.98								1,1/8 BSB
1.1250	28.58	0.0833	2.12				1, 1/8 UNF
1.1250	28.58	0.1111	2.82							1,1/8 BSF
1.1250	28.58	0.1429	3.63										1,1/8 WHIT
1.1250	28.58	0.1429	3.63					1,1/8 UNC
1.1811	30.00	0.0787	2.00		M30(F)
1.1811	30.00	0.1378	3.50	M30
1.2500	31.75	0.0385	0.98								1,1/4 BSB
1.2500	31.75	0.0833	2.12				1, 1/4 UNF
1.2500	31.75	0.1111	2.82							1,1/4 BSF
1.2500	31.75	0.1429	3.63										1,1/4 WHIT
1.2500	31.75	0.1429	3.63					1,1/4 UNC
1.2598	32.00	0.0591	1.50			M32(S)
1.2992	33.00	0.1378	3.50	M33
1.3750	34.93	0.0833	2.12				1, 3/8 UNF
1.3750	34.93	0.1250	3.18							1,3/8 BSF
1.3750	34.93	0.1667	4.23										1,3/8 WHIT
1.3750	34.93	0.1667	4.23					1,3/8 UNC
1.4173	36.00	0.1575	4.00	M36
1.5000	38.10	0.0385	0.98								1,1/2 BSB
1.5000	38.10	0.0833	2.12				1, 1/2 UNF
1.5000	38.10	0.1250	3.18							1,1/2 BSF
1.5000	38.10	0.1667	4.23										1,1/2 WHIT
1.5000	38.10	0.1667	4.23					1,1/2 UNC
1.5354	39.00	0.1575	4.00	M39
1.6250	41.28	0.2000	5.08										1,5/8 WHIT
1.6535	42.00	0.1772	4.50	M42
1.7500	44.45	0.1429	3.63							1,3/4 BSF
1.7500	44.45	0.2000	5.08										1,3/4 WHIT
1.7500	44.45	0.2000	5.08					1,3/4 UNC
1.7717	45.00	0.1772	4.50	M45
1.8750	47.63	0.2222	5.64										1,7/8 WHIT
1.9291	49.00	0.1969	5.00	M48
2.0000	50.80	0.1429	3.63							2 BSF
2.0000	50.80	0.2222	5.64										2 WHIT
2.0000	50.80	0.2222	5.64					2 UNC
2.0472	52.00	0.1969	5.00	M52
2.2047	56.00	0.2165	5.50	M56
2.2500	57.15	0.1667	4.23							2,1/4 BSF
2.2500	57.15	0.2222	5.64					2,1/4 UNC
2.2500	57.15	0.2500	6.35										2,1/4 WHIT
2.5000	63.50	0.1667	4.23							2,1/2 BSF
2.5000	63.50	0.2500	6.35										2,1/2 WHIT