Note: Allpar does not take responsibility for the veracity of any information or opinions here, does not claim expertise, and is not responsible for any consequences. Please proceed at your own risk.

Torque specifications for fasteners

A bolt of the same size, thread, and material in a given grade can generally be tightened to a given torque; for example, grade-5, 1/4-20 should be torqued no more than 7 ft-lb in cast iron or 6 ft-lb in aluminum. In grade 8, those numbers are 11 and 9. This should apply universally to all such bolts, with some exceptions, e.g. for different alloys.

This information is for the bolt shaft size, not the bolt head size. Bolt and fastened material alloys change these numbers.

These numbers are for reference only; compare them to the bolt maker’s specifications for confirmation. We suggest using them as a guide when you cannot obtain the car manufacturer’s or bolt maker’s specifications.

Metric Class 4T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
6	1	55 kgf-cm	48 in-lb	60 kgf-cm	52 in-lb
8	1.25	130 kgf-cm	108 in-lb	145 kgf-cm	10
10	1.25	26	19	29	21
12	1.25	47	35	53	39
14	1.5	74	55	84	61
16	1.5	115	83	–	-

Metric Class 5T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
6	1	65 kgf-cm	56 in-lb	75 kgf-cm	65 in-lb
8	1.25	160 kgf-cm	12	175 kgf-cm	13
10	1.25	32	24	36	26
12	1.25	59	43	65	48
14	1.5	91	67	100	76
16	1.5	140	101	-	-

Metric Class 6T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
6	1	80 kgf-cm	69 in-lb	90 kgf-cm	78 in-lb
8	1.25	19	14	21	15
10	1.25	39	29	44	32
12	1.25	71	53	80	90
14	1.5	110	80	125	90
16	1.5	170	127	-	-

Metric Class 7T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
6	1	110 kgf-cm	96 in-lb	120 kgf-cm	108 in-lb
8	1.25	25	19	28	21
10	1.25	52	38	58	43
12	1.25	95	70	105	76
14	1.5	145	108	165	123
16	1.5	230	166	-	-

Metric Class 8T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
8	1.25	29	22	33	24
10	1.25	61	45	68	50
12	1.25	110	80	120	90

Metric Class 9T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
8	1.25	34	25	37	27
10	1.25	70	51	78	57
12	1.25	125	94	140	105

Metric Class 10T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
8	1.25	38	28	42	31
10	1.25	78	58	88	64
12	1.25	140	105	155	116

Metric Class 11T
Dia	Pitch	Standard Hex-head Bolt		Flange-Headed Bolt
mm	mm	N•m	Ft-lb	N•m	Ft-lb
8	1.25	42	31	47	35
10	1.25	87	64	97	72
12	1.25	155	116	175	130

Metric Grade 9.8
Dia	Cast Iron		Aluminum
mm	N•m	Ft-lb	N•m	Ft-lb
6	9	5	7	4
7	14	9	11	7
8	25	18	18	14
10	40	30	30	25
12	70	55	55	40
14	115	85	90	65
16	180	130	140	100
18	230	170	180	135

Metric Grade 10.9
Dia	Cast Iron		Aluminum
mm	N•m	Ft-lb	N•m	Ft-lb
6	14	9	11	7
7	18	14	14	11
8	32	23	25	18
10	60	45	45	35
12	105	75	80	60
14	160	120	125	95
16	240	175	190	135
18	320	240	250	185

Metric Grade 12.9
Dia	Cast Iron		Aluminum
mm	N•m	Ft-lb	N•m	Ft-lb
6	14	9	11	7
7	25	18	18	14
8	36	27	25	21
10	70	50	55	40
12	125	95	100	75
14	195	145	150	110
16	290	210	220	165
18	400	290	310	230

SAE Grade 5					SAE Grade 8
Size	Cast Iron		Aluminum		Size	Cast Iron		Aluminum
Dia - tpi	N•m	Ft-lb	N•m	Ft-lb	Dia - tpi	N•m	Ft-lb	N•m	Ft-lb
1/4 – 20	9	7	8	6	1/4 – 20	15	11	12	9
1/4 – 28	12	9	9	7	1/4 – 28	18	13	14	10
5/16 – 18	20	15	16	12	5/16 – 18	30	22	24	18
5/16 – 24	23	17	19	14	5/16 – 24	33	24	25	19
3/8 – 16	40	30	25	20	3/8 – 16	55	40	40	30
3/8 – 24	40	30	35	25	3/8 – 24	60	45	45	35
7/16 – 14	60	45	45	35	7/16 – 14	90	65	65	50
7/16 – 20	65	50	55	40	7/16 – 20	95	70	75	55
1/2 – 13	95	70	75	55	1/2 – 13	130	95	100	75
1/2 – 20	100	75	80	60	1/2 – 20	150	110	120	90
9/16 – 12	135	100	110	80	9/16 – 12	190	140	150	110
9/16 – 18	150	110	115	85	9/16 – 18	210	155	170	125
5/8 – 11	180	135	150	110	5/8 – 11	255	190	205	150
5/8 – 18	210	155	160	120	5/8 – 18	290	215	230	170
3/4 – 10	325	240	255	190	3/4 – 10	460	340	365	270
3/4 – 16	365	270	285	210	3/4 – 16	515	380	410	300
7/8 – 9	480	360	380	280	7/8 – 9	745	550	600	440
7/8 – 14	530	390	420	310	7/8 – 14	825	610	660	490
1 – 8	720	530	570	420	1 – 8	1100	820	890	660
1 – 14	800	590	650	480	1 – 14	1200	890	960	710

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