Thread Size Reference Guide-International Standards

| Metric External Thread Chart

Metric threads, both external and internal, are extensively utilized in CNC machined parts. Threads play a crucial role in assembly, mating, and funct

ional adjustment. Our CNC machining services excel at producing precise threaded components that undergo thorough quality inspections using thread gauges.

Note: All dimensions specified are in millimeters.

Metric External Thread Chart
Thread Designation x Pitch	Tolerance Class	Major Dia.		Pitch Dia.		Minor Dia.
Thread Designation x Pitch	Tolerance Class	max.	min.	max.	min.	max.	min.
M1.6 x 0.35	6g	1.581	1.496	1.354	1.291	1.202	1.075
M2 x 0.25	6g	1.982	1.915	1.820	1.764	1.711	1.610
M2 x 0.4	6g	1.981	1.886	1.721	1.654	1.548	1.408
M2.5 x 0.35	6g	2.481	2.396	2.254	2.191	2.102	1.998
M2.5 x 0.45	6g	2.480	2.380	2.188	2.117	1.993	1.840
M2.6 x 0.45	6g	2.580	2.480	2.288	2.217	2.093	1.940
M3 x 0.35	6g	2.981	2.896	2.754	2.687	2.602	2.471
M3 x 0.5	6g	2.980	2.874	2.655	2.580	2.438	2.272
M3.5 x 0.6	6g	3.479	3.354	3.089	3.004	2.829	2.634
M4 x 0.5	6g	3.980	3.874	3.655	3.580	3.439	3.272
M4 x 0.7	6g	3.978	3.838	3.523	3.433	3.220	3.002
M5 x 0.5	6g	4.980	4.874	4.655	4.580	4.439	4.272
M5 x 0.8	6g	4.976	4.826	4.456	4.361	4.110	3.868
M6 x 0.5	6g	5.980	5.874	5.655	5.570	5.439	5.262
M6 x 0.75	6g	5.978	5.838	5.491	5.391	5.166	4.929
M6 x 1	6g	5.974	5.794	5.324	5.212	4.891	4.596
M7 x 0.5	6g	6.980	6.874	6.655	6.570	6.439	6.262
M7 x 1	6g	6.974	6.794	6.324	6.212	5.891	5.596
M8 x 0.5	6g	7.980	7.874	7.655	7.570	7.439	7.262
M8 x 0.75	6g	7.978	7.838	7.491	7.391	7.166	6.929
M8 x 1	6g	7.974	7.794	7.324	7.212	6.891	6.596
M8 x 1.25	6g	7.972	7.760	7.160	7.042	6.619	6.272
M9 x 0.5	6g	8.980	8.874	8.655	8.570	8.439	8.262
M9 x 1	6g	8.972	8.794	8.324	8.212	7.891	7.596
M9 x 1.25	6g	8.972	8.760	8.160	8.042	7.619	7.272
M10 x 0.75	6g	9.978	9.838	9.491	9.391	9.166	8.929
M10 x 1	6g	9.974	9.794	9.324	9.212	8.891	8.596
M10 x 1.25	6g	9.972	9.760	9.160	9.042	8.619	8.272
M10 x 1.5	6g	9.968	9.732	8.994	8.862	8.344	7.938
M11 x 0.5	6g	10.980	10.874	10.655	10.570	10.439	10.262
M11 x 1	6g	10.974	10.794	10.324	10.212	9.891	9.596
M11 x 1.5	6g	10.968	10.732	9.994	9.862	9.344	8.938
M12 x 0.5	6g	11.980	11.874	11.655	11.565	11.439	11.257
M12 x 1	6g	11.974	11.794	11.324	11.206	10.891	10.590
M12 x 1.25	6g	11.972	11.760	11.160	11.028	10.619	10.258
M12 x 1.5	6g	11.968	11.732	10.994	10.854	10.344	9.930
M12 x 1.75	6g	11.966	11.701	10.829	10.679	10.071	9.601
M14 x 0.5	6g	13.980	13.874	13.655	13.565	13.439	13.257
M14 x 1.5	6g	13.968	13.732	12.994	12.854	12.344	11.930
M14 x 2	6g	13.962	13.682	12.663	12.503	11.797	11.271

Thread Designation x Pitch	Tolerance Class	Major Dia.		Pitch Dia.		Minor Dia.
Thread Designation x Pitch	Tolerance Class	max.	min.	max.	min.	max.	min.
M15 x 1	6g	14.974	14.794	14.324	14.206	13.891	13.590
M16 x 0.5	6g	15.980	15.874	15.655	15.565	15.439	15.257
M16 x 1.5	6g	15.968	15.732	14.994	14.854	14.344	13.930
M16 x 2	6g	15.962	15.682	14.663	14.503	13.797	13.271
M17 x 1	6g	16.974	16.794	16.324	16.206	15.891	15.590
M18 x 1	6g	17.974	17.794	17.324	17.206	16.891	16.590
M18 x 1.5	6g	17.968	17.732	16.994	16.854	16.344	15.930
M20 x 1	6g	19.974	19.794	19.324	19.206	18.891	18.590
M20 x 1.5	6g	19.968	19.732	18.994	18.854	18.344	17.930
M20 x 2.5	6g	19.958	19.623	18.334	18.164	17.251	16.624
M22 x 1.5	6g	21.968	21.732	20.994	20.854	20.344	19.930
M22 x 2.5	6g	21.958	21.623	20.334	20.164	19.251	18.624
M24 x 2	6g	23.962	23.682	22.663	22.493	21.797	21.261
M24 x 3	6g	23.952	23.577	22.003	21.803	20.704	19.955
M25 x 1.5	6g	24.968	24.732	23.994	23.844	23.344	22.920
M27 x 2	6g	26.962	26.682	25.663	25.493	24.797	24.261
M27 x 3	6g	26.952	26.577	25.003	24.803	23.704	22.955
M30 x 1.5	6g	29.968	29.732	28.994	28.844	28.344	27.920
M30 x 2	6g	29.962	29.682	28.663	28.493	27.797	27.261
M30 x 3.5	6g	29.947	29.522	27.674	27.462	26.158	25.306
M32 x 2	6g	31.962	31.682	30.663	30.493	29.797	29.261
M33 x 2	6g	32.962	32.682	31.663	31.493	30.797	30.261
M35 x 1.5	6g	34.968	34.732	33.994	33.844	33.344	32.920
M36 x 2	6g	35.962	35.682	34.663	34.493	33.797	33.261
M36 x 4	6g	35.940	35.465	33.342	33.118	31.610	30.654
M39 x 2	6g	38.962	38.682	37.663	37.493	36.797	36.261
M40 x 1.5	6g	39.968	39.732	38.994	38.844	38.344	37.920
M42 x 2	6g	41.962	41.682	40.663	40.493	39.797	39.261
M42 x 4.5	6g	41.937	41.437	39.014	38.778	37.065	36.006
M45 x 1.5	6g	44.968	44.732	43.994	43.844	43.344	42.920
M48 x 2	6g	47.962	47.682	46.663	46.483	45.797	45.251
M48 x 5	6g	47.929	47.399	44.681	44.431	42.516	41.351
M50 x 1.5	6g	49.968	49.732	48.994	48.834	48.344	47.910
M55 x 1.5	6g	54.968	54.732	53.994	53.834	53.344	52.910
M56 x 2	6g	55.962	55.682	54.663	54.483	53.797	53.251
M56 x 5.5	6g	55.925	55.365	52.353	52.088	49.971	48.700
M60 x 1.5	6g	59.968	59.732	58.994	58.834	58.344	57.910

| Metric Internal Thread Chart

Internal threads are typically created using either a thread tap or a thread cutter, depending on the thread size. The choice of the appropriate thread cutting tool is essential, taking into consideration factors such as the raw material and thread dimensions. If you have any inquiries regarding CNC machining threads, feel free to reach out to us for assistance.

Metric Internal Thread Chart
Thread Designation	Tolerance Class	Minor Dia., D1		Pitch Dia., D2		Major Dia., D
Thread Designation	Tolerance Class	min.	max.	min.	max.	min.	max.
M1.6 x 0.35	6H	1.221	1.321	1.373	1.458	1.600	1.736
M2 x 0.4	6H	1.567	1.679	1.740	1.830	2.000	2.148
M2.5 x 0.45	6H	2.013	2.138	2.208	2.303	2.500	2.660
M3 x 0.5	6H	2.459	2.599	2.675	2.775	3.000	3.172
M3.5 x 0.6	6H	2.850	3.010	3.110	3.222	3.500	3.698
M4 x 0.7	6H	3.242	3.422	3.545	3.663	4.000	4.219
M5 x 0.8	6H	4.134	4.334	4.480	4.605	5.000	5.240
M6 x 1	6H	4.917	5.153	5.350	5.500	6.000	6.294
M8 x 1.25	6H	6.647	6.912	7.188	7.348	8.000	8.340
M8 x 1	6H	6.917	7.153	7.350	7.500	8.000	8.294
M10 x 1.5	6H	8.376	8.676	9.026	9.206	10.000	10.397
M10 x 1.25	6H	8.647	8.912	9.188	9.348	10.000	10.340
M10 x 1	6H	8.917	9.153	9.350	9.500	10.000	10.294
M10 x 0.75	6H	9.188	9.378	9.513	9.645	10.000	10.240
M12 x 1.75	6H	10.106	10.441	10.863	11.063	12.000	12.452
M12 x 1.5	6H	10.376	10.676	11.026	11.216	12.000	12.407
M12 x 1.25	6H	10.647	10.912	11.188	11.368	12.000	12.360
M12 x 1	6H	10.917	11.153	11.350	11.510	12.000	12.304
M14 x 2	6H	11.835	12.210	12.701	12.913	14.000	14.501
M14 x 1.5	6H	12.376	12.676	13.026	13.216	14.000	14.407
M15 x 1	6H	13.917	14.153	14.350	14.510	15.000	15.304
M16 x 2	6H	13.835	14.210	14.701	14.913	16.000	16.501
M16 x 1.5	6H	14.376	14.676	15.026	15.216	16.000	16.407
M17 x 1	6H	15.917	16.153	16.350	16.510	17.000	17.304
M18 x 1.5	6H	16.376	16.676	17.026	17.216	18.000	18.407
M20 x 2.5	6H	17.294	17.744	18.376	18.600	20.000	20.585
M20 x 1.5	6H	18.376	18.676	19.026	19.216	20.000	20.407
M20 x 1	6H	18.917	19.153	19.350	19.510	20.000	20.304
M22 x 2.5	6H	19.294	19.744	20.376	20.600	22.000	22.585
M22 x 1.5	6H	20.376	20.676	21.026	21.216	22.000	22.407
M24 x 3	6H	20.752	21.252	22.051	22.316	24.000	24.698
M24 x 2	6H	21.835	22.210	22.701	22.925	24.000	24.513
M25 x 1.5	6H	23.376	23.676	24.026	24.226	25.000	25.417
M27 x 3	6H	23.752	24.252	25.051	25.316	27.000	27.698
M27 x 2	6H	24.835	25.210	25.701	25.925	27.000	27.513
M30 x 3.5	6H	26.211	26.771	27.727	28.007	30.000	30.786
M30 x 2	6H	27.835	28.210	28.701	28.925	30.000	30.513
M30 x 1.5	6H	28.376	28.676	29.026	29.226	30.000	30.417
M33 x 2	6H	30.835	31.210	31.701	31.925	33.000	33.513
M35 x 1.5	6H	33.376	33.676	34.026	34.226	35.000	35.417
M36 x 4	6H	31.670	32.270	33.402	33.702	36.000	36.877
M36 x 2	6H	33.835	34.210	34.701	34.925	36.000	36.513
M39 x 2	6H	36.835	37.210	37.701	37.925	39.000	39.513
M40 x 1.5	6H	38.376	38.676	39.026	39.226	40.000	40.417
M42 x 4.5	6H	37.129	37.799	39.077	39.392	42.000	42.964
M42 x 2	6H	39.835	40.21	40.701	40.925	42.000	42.513
M45 x 1.5	6H	43.376	43.676	44.026	44.226	45.000	45.417
M48 x 5	6H	42.587	43.297	44.752	45.087	48.000	49.056
M48 x 2	6H	45.835	46.210	46.701	46.937	48.000	48.525
M50 x 1.5	6H	48.376	48.676	49.026	49.238	50.000	50.429
M55 x 1.5	6H	53.376	53.676	54.026	54.238	55.000	55.429
M56 x 5.5	6H	50.046	50.796	52.428	52.783	56.000	57.149
M56 x 2	6H	53.835	54.210	54.701	54.937	56.000	56.525
M60 x 1.5	6H	58.376	58.676	59.026	59.238	60.000	60.429

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| Metric External Thread Chart

| Metric Internal Thread Chart

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