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Technical Information

ISO General Purpose Metric Screw Threads

A screw thread in conformity with this International Standard is designated by the letter M followed by the values of the nominal diameter and of the pitch expressed in millimeters separated by the sign x.

Example : M 6 x 0.75 (Fine pitch 0.75)

The absence of the indication of pitch means that the coarse pitch is specified.

Example : M 6 (Coarse pitch 1.0)

The words "coarse" and "fine" are given in order to conform to usage. No concept of quality however, is associated with these words. "Coarse" pitches are the largest metric pitches used. For the diameter selected, choose one of the pitches shown on the corresponding line.

Diameter / Pitch Combinations

Nominal Diameters			Pitches
1st Choice	2nd Choice	3rd Choice	Coarse (mm)	Fine (mm)
M 1			0.25	0.2
	M 1.1		0.25	0.2
M 1.2			0.25	0.2
	M 1.4		0.3	0.2
M 1.6			0.35	0.2
	M 1.8		0.35	0.2
M 2			0.4	0.25
	M 2.2		0.45	0.25
M 2.5			0.45	0.35
M 3			0.5	0.35
	M 3.5		0.6	0.35
M 4			0.7	0.5
	M 4.5		0.75	0.5
M 5			0.8	0.5
		M 5.5		0.5
M6			1.0	0.75
		M 7	1	0.75
M 8			1.25	1, 0.75
		M 9	1.25	1, 0.75
M 10			1.5	1.25, 1, 0.75
		M 11	1.5	1, 0.75
M 12			1.75	1.5, 1.25, 1
	M14		2	1.5, 1.25, 1
		M 15		1.5, 1
M 16			2	1.5, 1
		M 17		1.5, 1
	M 18		2.5	2, 1.5, 1
M 20			2.5	2, 1.5, 1
	M 22		2.5	2, 1.5, 1
M 24			3	2, 1.5, 1
		M 25		2, 1.5, 1
		M 26		1.5
	M 27		3	2, 1.5, 1
		M 28		2, 1.5, 1
M 30			3.5	3, 2, 1.5, 1
		M 32		2, 1.5
	M 33		3.5	3, 2, 1.5
		M 35		1.5
M 36			4	3, 2, 1.5
		M 38		1.5
	M 39		4	3, 2, 1.5
		M 40		3, 2, 1.5
M 42			4.5	4, 3, 2, 1.5
	M 45		4, 5	4, 3, 2, 1.5
M 48			5	4, 3, 2, 1.5
		M 50		3, 2, 1.5
	M 52		5	4, 3, 2, 1.5
		M 55		4, 3, 2, 1.5
M 56			5.5	4, 3, 2, 1.5
		M 58		4, 3, 2, 1.5
	M 60		5.5	4, 3, 2, 1.5
		M 62		4, 3, 2, 1.5
M 64			6	4, 3, 2, 1.5
		M 65		4, 3, 2, 1.5
	M 68		6	4, 3, 2, 1.5
		M 70		6, 4, 3, 2, 1.5
M 72				6, 4, 3, 2, 1.5
		M 75		4, 3, 2, 1.5
	M 76			6, 4, 3, 2, 1.5
		M 78		2
M 80				6, 4, 3, 2, 1.5
		M 82		2
	M 85			6, 4, 3, 2
M 90				6, 4, 3, 2
	M 95			6, 4, 3, 2
M 100				6, 4, 3, 2
	M 105			6, 4, 3, 2
M 110				6, 4, 3, 2
	M 115			6, 4, 3, 2
	M 120			6, 4, 3, 2
M 125				6, 4, 3, 2
	M 130			6, 4, 3, 2
		M 135		6, 4, 3, 2
M 140				6, 4, 3, 2
		M 145		6, 4, 3, 2
	M 150			6, 4, 3, 2
		M 155		6, 4, 3
M 160				6, 4, 3
		M 165		6, 4, 3
	M 170			6, 4, 3
		M 175		6, 4, 3
M 180				6, 4, 3
		M 185		6, 4, 3
	M 190			6, 4, 3
		M 195		6, 4, 3
M 200				6, 4, 3
		M 205		6, 4, 3
	M 210			6, 4, 3
		M215		6, 4, 3
M 220				6, 4, 3
		M 225		6, 4, 3
		M 230		6, 4, 3
		M 235		6, 4, 3
	M 240			6, 4, 3
		M 245		6, 4, 3
M 250				6, 4, 3
		M 255		6, 4
	M 260			6, 4
		M 265		6, 4
		M 270		6, 4
		M 275		6, 4
M 280				6, 4
		M 285		6, 4
		M 290		6, 4
		M 295		6, 4
	M 300			6, 4

Limits of Sizes for Bolt & Nut Threads

Reference No.: ISO 965/1-1980, ISO 965/2-1980

Bolt Threads (Coarse)

MAJOR DIAMETER		PITCH DIAMETER		Root Radius (min. 1)
max.	min.	max.	min.
1,000	0,933	0,838	0,785	0,031
1,100	1,033	0,938	0,885	0,031
1,200	1,133	1,038	0,985	0,031
1,400	1,325	1,205	1,149	0,038
1,581	1,496	1,354	1,291	0,044
1,781	1,696	1,554	1,491	0,044
1,981	1,886	1,721	1,654	0,050
2,180	2,080	1,888	1,817	0,056
2,480	2,380	2,188	2,117	0,056
2,980	2,874	2,655	2,580	0,063
3,479	3,354	3,089	3,004	0,075
3,978	3,838	3,523	3,433	0,088
4,478	4,338	3,991	3,901	0,094
4,976	4,826	4,456	4,361	0,100
5,974	5,794	5,324	5,212	0,125
6,974	6,794	6,324	6,212	0,125
7,972	7,760	7,160	7,042	0,156
9,968	9,732	8,994	8,862	0,188
11,966	11,701	10,829	10,679	0,219
13,962	13,682	12,663	12,503	0,250
15,962	15,682	14,663	14,503	0,250
17,958	17,623	16,334	16,164	0,313
19,958	19,623	18,334	18,164	0,313
21,958	21,623	20,334	20,164	0,313
23,952	23,577	22,003	21,803	0,375
26,952	26,577	25,003	24,803	0,375
29,947	29,522	27,674	27,462	0,438
32,947	32,522	30,674	30,462	0,438
35,940	35,465	33,342	33,118	0,500
38,940	38,465	36,342	36,118	0,500

BOLT THREADS (FINE)

MAJOR DIAMETER		PITCH DIAMETER		Root Radius (min. 1)
max.	min.	max.	min.
7,974	7,794	7,324	7,212	0,125
9,972	9,760	9,160	9,042	0,156
11,972	11,760	11,160	11,028	0,156
13,968	13,732	12,994	12,854	0,188
15,968	15,732	14,994	14,854	0,188
17,968	17,732	16,994	16,854	0,188
19,968	19,732	18,994	18,854	0,188
21,968	21,732	20,994	20,854	0,188
23,962	23,682	22,663	22,493	0,250
26,962	26,682	25,663	25,493	0,250
29,962	29,682	28,663	28,493	0,250
32,962	32,682	31,663	31,493	0,250
35,952	35,577	34,003	33,803	0,375
38,952	38,577	37,003	36,803	0,375

NUT THREADS (COARSE)

PITCH DIAMETER		MINOR DIAMETER
max.	min.	max.	min.
0,894	0,838	0,785	0,729
0,994	0,938	0,885	0,729
1,094	1,038	0,985	0,929
1,265	1,205	1,142	1,075
1,458	1,373	1,321	1,221
1,658	1,573	1,521	1,421
1,830	1,740	1,679	1,567
2,003	1,908	1,838	1,713
2,303	2,208	2,138	2,013
2,775	2,675	2,599	2,459
3,222	3,110	3,010	2,850
3,663	3,545	3,422	3,242
4,131	4,013	3,878	3,688
4,605	4,480	4,334	4,134
5,500	5,350	5,153	4,917
6,500	6,350	6,153	5,917
7,348	7,188	6,912	6,647
9,206	9,026	8,676	8,376
11,063	10,863	10,441	10,106
12,913	12,701	12,210	11,835
14,913	14,701	14,210	13,835
16,600	16,376	15,744	15,294
18,600	18,376	17,744	17,294
20,600	20,376	19,744	19,294
22,316	22,051	21,252	20,752
25,316	25,051	24,252	23,752
28,007	27,727	26,771	26,211
31,007	30,727	29,771	29,211
33,702	33,402	32,270	31,670
36,702	36,402	35,270	34,670

NUT THREADS (FINE)

PITCH DIAMETER		MINOR DIAMETER
max.	min.	max.	min.
7,500	7,350	7,153	6,917
9,348	9,188	8,912	8,647
11,368	11,188	10,912	10,647
13,216	13,026	12,676	12,376
15,216	15,026	14,676	14,376
17,216	17,026	16,676	16,376
19,216	19,026	18,676	18,376
21,216	21,026	20,676	20,376
22,925	22,701	22,210	21,835
25,925	25,701	25,210	24,835
28,925	28,701	28,210	27,835
31,925	31,701	31,210	30,835
34,316	34,051	33,252	32,752
37,316	37,051	36,252	35,752

(COARSE)

Thread Size in mm	Length of Thread engagement
	over	up to and incl.
M 1	0,6	1,7
M 1, 1	0,6	1,7
M 1, 2	0, 6	1, 7
M 1, 4	0, 7	2
M 1, 6	0, 8	2, 6
M 1, 8	0, 8	2, 6
M 2	1	3
M 2, 2	1, 3	3, 8
M 2, 5	1, 3	3, 8
M 3	1, 5	4, 5
M 3, 5	1, 7	5
M 4	2	6
M 4, 5	2, 2	6, 7
M 5	2, 5	7, 5
M 6	3	9
M 7	3	3
M 8	4	12
M 10	5	15
M 12	6	18
M 14	8	24
M 16	8	24
M 18	10	30
M 20	10	30
M 22	10	30
M 24	12	36
M 27	12	36
M 30	15	45
M 33	15	45
M 36	18	53
M 39	18	53

(FINE)

Thread Size in mm	Length of Thread engagement
	over	up to and incl.
M 8 x 1	3	9
M 10 x 1,25	4	12
M 12 x 1,25	4, 5	13
M 14 x 1,5	5, 6	16
M 16 x 1,5	5, 6	16
M 18 x 1,5	5, 6	16
M 20 x 1,5	5, 6	16
M 22 x 1,5	5, 6	16
M 24 x 2	8, 5	25
M 27 x 2	8, 5	25
M 30 x 2	8, 5	25
M 33 x 2	8, 5	25
M 36 x 3	12	36
M 39 x 3	12	36

Screw Thread Conversion Table

MAJOR DIAMETER

NOMINAL DIAMETER (mm)	MAJOR DIAMETER
	mm	INCH
M 1	1	.0393
M 1.1	1.1	.0433
M 1.2	1.2	.0472
M 1.4	1.4	.0551
M 1.6	1.6	.0629
M 1.8	1.8	.0708
M 2	2	.0787
M 2.2	2.2	.0866
M 2.3	2.3	.0905
M 2.5	2.5	.0984
M 2.6	2.6	.1023
M 3	3	.1181
M 3.5	3.5	.1378
M 4	4	.1574
M 4.5	4.5	.1771
M 5	5	.1968
M 6	6	.2362
M 7	7	.2755
M 8	8	.3149
M 10	10	.3937
M 12	12	.4724
M 14	14	.5511
M 16	16	.6299
M 18	18	.7086
M 20	20	.874
M 22	22	.8661
M 24	24	.9448
M 27	27	1.0629
M 30	30	1.181
M 33	33	1.299
M 36	36	1.417
M 39	39	1.535
M 42	42	1.654
M 45	45	1.772
M 48	48	1.890
M 52	52	2.047
M 56	56	2.205
M 60	60	2.362
M 64	64	2.520
M 68	68	2.677
M 72	72	2.835
M 76	76	2.992
M 80	80	3.150
M 85	85	3.346
M 90	90	3.543
M 95	95	3.740
M 100	100	3.937
M 105	105	4.134
M 110	110	4.331
M 115	115	4.538
M 120	120	4.724
M 125	125	4.921
M 130	130	5.118
M 135	135	5.315
M 140	140	5.512
M 145	145	5.709
M 150	150	5.906

THREAD PITCH

PITCH (mm)	Approx. Threads per Inch
0.08	317.5
0.09	282.25
0.1	254
0.125	203.25
0.15	169.25
0.175	145.25
0.2	127
0.225	113
0.25	101.5
0.3	84.75
0.35	72.5
0.4	63.5
0.45	56.5
0.5	50.75
0.6	42.25
0.7	36.25
0.75	33.75
0.8	31.75
0.9	25.25
1	25.5
1.25	20.25
1.5	17
1.75	14.25
2	12.75
2.5	10.25
3	8.5
3.5	7.25
4	6.25
5	5
5.5	4.5
6	4.25

US / Metric Conversion Equivalents

To convert length to mm multiply inches by 25.4

To convert length to inches multiply mm by .039370

LENGTH CONVERSION

U.S. TO METRIC		METRIC TO U.S.
1 inch	25.400 millimetres	1 millimetre	: .03937 inches
1 inch	2.540 centimetres	1 centimetre	: .39370 inches
1 foot	30.480 centimetres	1 metre	: 3.2808 feet
1 yard	0.9144 metres	1 metre	: 1.0936 yards
1 mile	1,609 kilometres	1 centimetre	: .62137 miles

AREA CONVERSION

U.S. TO METRIC		METRIC TO U.S.
1 sq. inch	6.4516 sq. centimetres	1 sq. centimetre	: .1550 sq. inches
1 sq. foot	.0929 sq. metres	1 sq. metre	: 10.764 sq. feet
1 sq. mile	2.5889 sq. kilometres	1 sq. kilometre	: .38614 sq. miles

AREA

Sq. Inch	centimetre square	centimetre square	Sq. Inch
1	6.45	1	.1550
2	12.90	2	.310
3	2.5889 sq. kilometres	3	.456
4	25.81	4	.620
5	32.26	5	.775
Sq. Feet	metre square	metre square	Sq. Feet
1	.093	1	10.76
2	.186	2	21.53
3	.279	3	32.29
4	.372	4	43.06
5	.465	5	53.82

VOLUME

Cu. Inch	centimetre cube	centimetre cube	Cu. Inch
1	16.39	1	.061
2	32.77	2	.122
3	49.16	3	.183
4	65.55	4	.244
5	81.94	5	.305
Cu. Feet	metre cube	metre cube	Cu. Feet
1	.028	1	.061
2	.057	2	70.63
3	.085	3	105.94
4	.113	4	141.26
5	.142	5	176.57

CAPACITY

Quart	Liter	Liter	Quart
1	1.101	1	.908
2	2.202	2	1.816
3	3.303	3	2.724
4	4.404	4	3.632
5	5.505	5	4.540
US Gallon	Liter	Liter	US Gallon
1	3.79	1	.26
2	7.57	2	.53
3	11.36	3	.79
4	15.14	4	1.06
5	18.93	5	1.32

MASS (WEIGHT)

Lb.	kg	kg	Lb.
1	.45	1	2.20
2	.91	2	4.41
3	1.36	3	6.61
4	1.81	4	8.82
5	2.27	5	11.02
Oz.	gr	gr	Oz.
1	28.35	1	.035
2	56.70	2	.071
3	85.05	3	.106
4	113.40	4	.141
5	141.75	5	.176

PRESSURE

Lb. / Sq. In	kg / centimetre square	kg / centimetre square	Lb. / Sq. In
1	.070	1	14.22
2	.141	2	28.45
3	.211	3	42.67
4	.281	4	56.89
5	.352	5	71.12
Lb. / Sq. Ft.	kg / metre square	kg / metre square	Lb. / Sq. Ft.
1	4.88	1	.20
2	9.76	2	.41
3	14.65	3	.61
4	19.53	4	.82
5	24.41	5	1.02