Metric Thread Plug Gauge Size Chart M1

Reference Data · ISO 1502 · ISO 261 · DIN 13 · 6H Tolerance

Metric Thread Plug Gauge Size Chart:
M1 to M100 with Tolerance Limits

📅 Updated 2026·Reference Chart· ISO 1502 · ISO 261 · DIN 13 · 4H · 6H · 7H

// Direct Answer

This page provides complete metric thread plug gauge size charts for GO and NO-GO members in tolerance class 6H, covering coarse pitch sizes from M1 to M100 per ISO 1502 and ISO 261. All dimensions are in millimetres. The GO gauge pitch diameter limits and NO-GO gauge pitch diameter limits are shown for each size. Use the size and pitch from your engineering drawing to find the correct gauge limits before ordering.

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How to Read This Chart M1 – M10 Coarse M12 – M30 Coarse M33 – M68 Coarse M72 – M100 Coarse Fine Pitch Common Sizes Other Tolerance Classes Related Articles FAQ

How to Read This Chart

Each row shows one thread size. The GO gauge pitch diameter limits control the minimum material condition of the internal thread — the GO gauge must pass through fully. The NO-GO gauge pitch diameter limits control the maximum material condition — the NO-GO gauge must not engage more than two turns.

// HOW TO READ — COLUMN DEFINITIONS

Column	Definition	Unit
Thread	Nominal thread designation (e.g. M12×1.75)	—
Pitch	Thread pitch — distance between crests	mm
GO PD Max	GO gauge pitch diameter upper limit — gauge must not exceed this	mm
GO PD Min	GO gauge pitch diameter lower limit — gauge must not be below this	mm
NO-GO PD Max	NO-GO gauge pitch diameter upper limit	mm
NO-GO PD Min	NO-GO gauge pitch diameter lower limit	mm
Workpiece 6H Max	Maximum allowable pitch diameter of the inspected internal thread	mm
Workpiece 6H Min	Minimum allowable pitch diameter of the inspected internal thread	mm

Standard reference: All gauge limits on this page are derived from ISO 1502 (gauges for ISO metric threads) and ISO 261 / DIN 13 (ISO general-purpose metric screw threads). Tolerance class 6H applies unless otherwise stated. For other tolerance classes (4H, 5H, 7H), contact GageTools with your specific drawing callout.

M1 – M10 Coarse Pitch — 6H Thread Plug Gauge Limits

Standard: ISO 1502 · ISO 261 · DIN 13. Tolerance class: 6H. All dimensions in mm.

// M1 – M10 COARSE PITCH · 6H · PLUG GAUGE PITCH DIAMETER LIMITS (mm)

Thread	Pitch mm	GO PD Max	GO PD Min	NO-GO PD Max	NO-GO PD Min	Work 6H Max	Work 6H Min	Order
M1	0.25	0.838	0.834	0.854	0.850	0.854	0.838	Quote
M1.2	0.25	1.038	1.034	1.054	1.050	1.054	1.038	Quote
M1.4	0.30	1.205	1.201	1.224	1.220	1.224	1.205	Quote
M1.6	0.35	1.373	1.369	1.393	1.389	1.393	1.373	Quote
M1.8	0.35	1.573	1.569	1.593	1.589	1.593	1.573	Quote
M2	0.40	1.740	1.736	1.763	1.759	1.763	1.740	Quote
M2.2	0.45	1.908	1.903	1.933	1.928	1.933	1.908	Quote
M2.5	0.45	2.208	2.203	2.233	2.228	2.233	2.208	Quote
M3	0.50	2.675	2.670	2.703	2.698	2.703	2.675	Quote
M3.5	0.60	3.110	3.104	3.142	3.136	3.142	3.110	Quote
M4	0.70	3.545	3.539	3.580	3.574	3.580	3.545	Quote
M4.5	0.75	4.013	4.007	4.051	4.045	4.051	4.013	Quote
M5	0.80	4.480	4.474	4.520	4.514	4.520	4.480	Quote
M6	1.00	5.350	5.342	5.400	5.392	5.400	5.350	Quote
M7	1.00	6.350	6.342	6.400	6.392	6.400	6.350	Quote
M8	1.25	7.188	7.179	7.248	7.239	7.248	7.188	Quote
M9	1.25	8.188	8.179	8.248	8.239	8.248	8.188	Quote
M10	1.50	9.026	9.016	9.096	9.086	9.096	9.026	Quote

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M12 – M30 Coarse Pitch — 6H Thread Plug Gauge Limits

// M12 – M30 COARSE PITCH · 6H · PLUG GAUGE PITCH DIAMETER LIMITS (mm)

Thread	Pitch mm	GO PD Max	GO PD Min	NO-GO PD Max	NO-GO PD Min	Work 6H Max	Work 6H Min	Order
M11	1.50	10.026	10.016	10.096	10.086	10.096	10.026	Quote
M12	1.75	10.863	10.852	10.943	10.932	10.943	10.863	Quote
M14	2.00	12.701	12.689	12.791	12.779	12.791	12.701	Quote
M16	2.00	14.701	14.689	14.791	14.779	14.791	14.701	Quote
M18	2.50	16.376	16.363	16.476	16.463	16.476	16.376	Quote
M20	2.50	18.376	18.363	18.476	18.463	18.476	18.376	Quote
M22	2.50	20.376	20.363	20.476	20.463	20.476	20.376	Quote
M24	3.00	22.051	22.037	22.161	22.147	22.161	22.051	Quote
M25	3.00	23.051	23.037	23.161	23.147	23.161	23.051	Quote
M27	3.00	25.051	25.037	25.161	25.147	25.161	25.051	Quote
M30	3.50	27.727	27.712	27.847	27.832	27.847	27.727	Quote

M33 – M68 Coarse Pitch — 6H Thread Plug Gauge Limits

// M33 – M68 COARSE PITCH · 6H · PLUG GAUGE PITCH DIAMETER LIMITS (mm)

Thread	Pitch mm	GO PD Max	GO PD Min	NO-GO PD Max	NO-GO PD Min	Work 6H Max	Work 6H Min	Order
M33	3.50	30.727	30.712	30.847	30.832	30.847	30.727	Quote
M36	4.00	33.402	33.386	33.532	33.516	33.532	33.402	Quote
M39	4.00	36.402	36.386	36.532	36.516	36.532	36.402	Quote
M42	4.50	39.077	39.060	39.217	39.200	39.217	39.077	Quote
M45	4.50	42.077	42.060	42.217	42.200	42.217	42.077	Quote
M48	5.00	44.752	44.734	44.902	44.884	44.902	44.752	Quote
M52	5.00	48.752	48.734	48.902	48.884	48.902	48.752	Quote
M56	5.50	52.428	52.409	52.588	52.569	52.588	52.428	Quote
M60	5.50	56.428	56.409	56.588	56.569	56.588	56.428	Quote
M64	6.00	60.103	60.083	60.273	60.253	60.273	60.103	Quote
M68	6.00	64.103	64.083	64.273	64.253	64.273	64.103	Quote

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M72 – M100 Coarse Pitch — 6H Thread Plug Gauge Limits

// M72 – M100 COARSE PITCH · 6H · PLUG GAUGE PITCH DIAMETER LIMITS (mm)

Thread	Pitch mm	GO PD Max	GO PD Min	NO-GO PD Max	NO-GO PD Min	Work 6H Max	Work 6H Min	Order
M72	6.00	68.103	68.083	68.273	68.253	68.273	68.103	Quote
M76	6.00	72.103	72.083	72.273	72.253	72.273	72.103	Quote
M80	6.00	76.103	76.083	76.273	76.253	76.273	76.103	Quote
M85	6.00	81.103	81.083	81.273	81.253	81.273	81.103	Quote
M90	6.00	86.103	86.083	86.273	86.253	86.273	86.103	Quote
M95	6.00	91.103	91.083	91.273	91.253	91.273	91.103	Quote
M100	6.00	96.103	96.083	96.273	96.253	96.273	96.103	Quote

Fine Pitch Common Sizes — 6H Thread Plug Gauge Limits

Fine pitch threads must always include the pitch in the designation — e.g. M12×1.25, not M12. Fine pitch gauges are not interchangeable with coarse pitch gauges of the same nominal diameter. See our Tolerance Classes Guide for more on fine pitch thread selection.

// FINE PITCH COMMON SIZES · 6H · PLUG GAUGE PITCH DIAMETER LIMITS (mm)

Thread	Pitch mm	GO PD Max	GO PD Min	NO-GO PD Max	NO-GO PD Min	Work 6H Max	Work 6H Min	Order
M8×1.0	1.00	7.350	7.342	7.400	7.392	7.400	7.350	Quote
M10×1.0	1.00	9.350	9.342	9.400	9.392	9.400	9.350	Quote
M10×1.25	1.25	9.188	9.179	9.248	9.239	9.248	9.188	Quote
M12×1.0	1.00	11.350	11.342	11.400	11.392	11.400	11.350	Quote
M12×1.25	1.25	11.188	11.179	11.248	11.239	11.248	11.188	Quote
M14×1.5	1.50	13.026	13.016	13.096	13.086	13.096	13.026	Quote
M16×1.5	1.50	15.026	15.016	15.096	15.086	15.096	15.026	Quote
M18×1.5	1.50	17.026	17.016	17.096	17.086	17.096	17.026	Quote
M20×1.5	1.50	19.026	19.016	19.096	19.086	19.096	19.026	Quote
M20×2.0	2.00	18.701	18.689	18.791	18.779	18.791	18.701	Quote
M24×2.0	2.00	22.701	22.689	22.791	22.779	22.791	22.701	Quote
M30×2.0	2.00	28.701	28.689	28.791	28.779	28.791	28.701	Quote

Other Tolerance Classes — 4H, 5H, 7H

The charts above show 6H tolerance limits — the most common for general engineering. For other tolerance classes, the GO and NO-GO pitch diameter limits are different. The table below shows how the limits shift for each class on an M12×1.75 example.

Tolerance Class	GO PD Max (mm)	GO PD Min (mm)	NO-GO PD Max (mm)	NO-GO PD Min (mm)	Typical Use
4H	10.863	10.854	10.907	10.898	Aerospace · Precision assemblies
5H	10.863	10.851	10.923	10.911	Automotive · Medium precision
6H ★	10.863	10.852	10.943	10.932	General engineering — standard
7H	10.863	10.849	10.983	10.969	Plated parts · Easy assembly

Need 4H or 7H gauge limits for a different size? Send your thread callout (e.g. M20×2.5 4H) via WhatsApp or email and we will confirm the exact GO and NO-GO pitch diameter limits for your specific size and tolerance class before production. Response within 24 hours.

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Send the nominal size and pitch, internal or external thread, tolerance class, plug or ring gauge type, GO/NO-GO requirement, quantity and required inspection or calibration documents.

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Frequently Asked Questions

What is the difference between GO gauge limits and workpiece limits?

The workpiece limits define the acceptable range for the machined thread. The gauge limits are tighter than the workpiece limits — the gauge is manufactured closer to the boundary it controls so that it correctly accepts or rejects workpieces. For a 6H GO gauge, the gauge pitch diameter maximum equals the workpiece pitch diameter minimum — ensuring that a GO gauge just at its own limit still represents the boundary of workpiece acceptance. This is the principle defined in ISO 1502.

Can I use the same gauge for coarse and fine pitch threads of the same diameter?

No. A coarse pitch gauge and a fine pitch gauge of the same nominal diameter have different pitch diameter limits because the pitch changes the thread geometry. An M12×1.75 6H gauge cannot be used to inspect an M12×1.25 6H thread — they require separate gauges. Always check both the nominal diameter and the pitch when ordering or selecting a gauge.

How do I find the correct gauge limits for a size not in this chart?

For sizes not shown in this chart — including non-standard pitches, intermediate diameters, or tolerance classes other than 6H — send your complete thread callout (nominal diameter, pitch, tolerance class) to GageTools via WhatsApp or email. We will calculate the exact gauge limits from ISO 1502 and confirm the correct gauge specification before production. Response within 24 hours.

What does the calibration certificate show for a plug gauge?

The ISO/IEC 17025 calibration certificate for a thread plug gauge shows the actual measured pitch diameter of both GO and NO-GO members, compared against the limits shown in this chart. It also shows the actual major diameter, minor diameter, pitch, and thread angle. Comparing the actual measured value with the limits tells you how much wear budget the gauge has remaining before it needs replacement. See our Calibration Certificate Reading Guide for a full explanation.

Order Any Size from This Chart

GageTools manufactures metric thread plug gauges for all sizes M1 to M100 in coarse and fine pitch, tolerance classes 4H, 5H, 6H, and 7H. ISO/IEC 17025 calibration certificate showing actual measured pitch diameter limits, available on request. MOQ 1 piece. Standard sizes ship in 72 hours.

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Metric Thread Plug Gauge Size Chart: M1 to M100 with Tolerance Limits

How to Read This Chart

M1 – M10 Coarse Pitch — 6H Thread Plug Gauge Limits

M12 – M30 Coarse Pitch — 6H Thread Plug Gauge Limits

M33 – M68 Coarse Pitch — 6H Thread Plug Gauge Limits

M72 – M100 Coarse Pitch — 6H Thread Plug Gauge Limits

Fine Pitch Common Sizes — 6H Thread Plug Gauge Limits

Other Tolerance Classes — 4H, 5H, 7H

Turn a Metric Size into a Gauge RFQ

Frequently Asked Questions

Order Any Size from This Chart

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