What is difference between the Metric M4 screw dimensions and UNC?

We may see a lot of M4 machine screws in our life and curious what is the exactly M4 screw dimensions are? Metric thread screw is the ISO metric screw thread, Metric threads are manufactured according to strict specifications defined, which is the most commonly used type of general-purpose screw thread worldwide, The “M” designation for metric screws indicates the nominal outer diameter of the screw thread, in millimeters.UNC – Unified National Coarse Thread, comparable with the ISO metric thread.

What is the difference between the m4 metric oval head machine screw dimensions and UNC oval head screw dimensions? The biggest difference between the metric M4 oval head screw and UNC # 4 oval head screws is that thread diameter and thread pitch are different. Of course, their head diameter and thickness are different. M4 oval head screws and UNC # 4 oval head screws are two completely different sizes of screws. You can refer to the following drawings for specific dimensions:

M4 Metric Oval Countersunk Head Machine Screw Dimensions

Screw Thread(d)	Screw Thread	M2	M2.5	M3	M3.5	M4	M5	M6	M8	M10
P	Pitch	0.4	0.45	0.5	0.6	0.7	0.8	1	1.25	1.5
ds	max	2.00	2.50	3	3.50	4.00	5.00	6.00	8.00	10.00
ds	min	1.65	2.12	2.58	3.00	3.43	4.36	5.21	7.04	8.86
dk	max	4.4	5.5	6.3	8.2	9.4	10.4	12.6	17.3	20.0
dk	min	2.5	4.4	5.2	6.9	8.0	8.9	10.9	15.4	17.8
k	max	1.2	1.5	1.7	2.3	2.7	2.7	3.3	4.6	5.0
n	max	0.7	0.8	1.0	1.2	1.5	1.5	1.9	2.3	2.8
n	min	0.5	0.6	0.8	1.0	1.2	1.2	1.6	2.0	2.5
t	max	1.0	1.2	1.5	1.7	1.9	2.4	2.8	3.7	4.4
t	min	0.8	1.0	1.2	1.4	1.6	2.0	2.4	3.2	3.8

M4 ASME B 18.6.3 – 2013 82° Slotted Undercut Oval Countersunk Head Machine Screw Dimension

Thread Size	Thread size	0#	1#	2#	3#	4#	5#	6#	8#	10#	12#	1/4	5/16	3/8	7/16	1/2
d	Nominal Size	0.0600	0.0730	0.0860	0.0990	0.1120	0.1250	0.1380	0.1640	0.1900	0.2160	0.2500	0.3125	0.3750	0.4375	0.5000
pp	UNC	–	64	56	48	40	40	32	32	24	24	20	18	16	14	13
L		1/8	1/8	1/8	1/8	3/16	3/16	3/16	1/4	5/16	3/8	7/16	1/2	9/16	5/8	3/4
Dk	max	0.112	0.137	0.162	0.187	0.212	0.237	0.262	0.312	0.362	0.412	0.477	0.597	0.717	0.760	0.815
dk	min	0.096	0.120	0.144	0.167	0.191	0.215	0.238	0.285	0.333	0.380	0.442	0.556	0.670	0.715	0.765
k	Ref	0.025	0.031	0.036	0.042	0.047	0.053	0.059	0.070	0.081	0.092	0.107	0.134	0.161	0.156	0.156
f	Ref	0.021	0.025	0.029	0.033	0.037	0.041	0.045	0.052	0.060	0.068	0.079	0.099	0.117	0.122	0.131
n	max	0.023	0.026	0.031	0.035	0.039	0.043	0.048	0.054	0.060	0.067	0.075	0.084	0.094	0.094	0.106
	min	0.016	0.019	0.023	0.027	0.031	0.035	0.039	0.045	0.050	0.056	0.064	0.072	0.081	0.081	0.091
t	max	0.028	0.034	0.040	0.047	0.053	0.059	0.065	0.078	0.090	0.103	0.119	0.149	0.179	0.184	0.204
	min	0.022	0.027	0.033	0.038	0.043	0.048	0.053	0.064	0.074	0.085	0.098	0.124	0.149	0.154	0.169

Oval head machine screws have a lot of specifications, are also innumerable, apart from the metric UNC system, different customers need different lengths of oval head screws. Also, m4 metric oval head Machine screw specifications can be M4x6, M4x7, M4x7.5, M4x8, M5x9…M4x300…M4x500, etc, no matter what you need metric M4 oval head screws, or M5, M3, M6, M8, M10, M12, M16, M20 or more, Or if you have any question about M4 screw dimensions and chart, You can find at Heatfastener

Related Products

Related Articles