Metric Thread Chart

Thread Dimensions and Tolerances

General

The accuracy of thread dimensions and profiles is crucial for determining:

1. Whether a coating can still be applied to the screw thread.

2. Whether the parts to be joined can be assembled easily without reworking.

3. Whether the thread can transmit the designed forces effectively.

Because tolerances in screw manufacturing are very small, understanding the terms and fitting systems is essential. The following explanations and diagrams clarify the key concepts of thread dimensions and tolerances.

Basic Concept and Nominal Dimensions (ISO 724)

According to ISO 724, the dimensioning system for threads is based on nominal dimensions, which include:

Major diameter (D, d)

Pitch diameter (D2, d2)

Minor diameter (D1, d1)

Pitch (P)

The nominal size of the thread defines its basic geometry for both the nut (internal thread) and the bolt (external thread).

Clearance Fit on Metric ISO Threads (ISO 965)

According to ISO 965, screw and nut threads are manufactured with different tolerance zone positions:

1. Screw (external) threads: dimensions are situated at or below the nominal size.

2. Nut (internal) threads: dimensions are situated at or above the nominal size.

This difference ensures:

1. The necessary clearance for easy assembly.

2. A defined range for permissible plating thicknesses.

For plated screw threads:

1. The screw must never exceed the nominal dimensions.

2. The nut must never fall below them.

This ensures proper fitting and functionality even after coatings or plating are applied.

THREAD CHART (METRIC THREADS)

THREAD DATA CHART: Metric Thread -- Fine Pitch
Nominal Size ISO MF	Major Diameter mm d=D	Pitch mm p	Root Radius mm r	Pitch Diameter mm d2=D2	Minor Diameter Male Thd. d3	Minor Diameter Female Thd. D1	Thread Height Male Thd. h3	Thread Height Female Thd. H1	Tap Drill Diameter mm
M8x0.75	8.00	0.75	0.108	7.513	7.080	7.188	0.460	0.406	7.20
M8x1.0	8.00	1.00	0.144	7.350	6.773	6.917	0.613	0.541	7.00
M10x0.75	10.00	0.75	0.108	9.513	9.080	9.188	0.460	0.406	9.20
M10x1.0	10.00	1.00	0.144	9.350	8.773	8.917	0.613	0.541	9.00
M10x1.25	10.00	1.25	0.180	9.188	8.466	8.647	0.767	0.677	8.80
M12x1.0	12.00	1.00	0.144	11.350	10.773	10.917	0.613	0.541	11.00
M12x1.25	12.00	1.25	0.180	11.188	10.466	10.647	0.767	0.677	10.80
M12x1.5	12.00	1.50	0.217	11.026	10.160	10.376	0.920	0.812	10.50
M14x1.0	14.00	1.00	0.144	13.350	12.773	12.917	0.613	0.541	13.00
M14x1.25	14.00	1.25	0.180	13.188	12.466	12.647	0.767	0.677	12.80
M14x1.5	14.00	1.50	0.217	13.026	12.160	12.376	0.920	0.812	12.50
M16x1.0	16.00	1.00	0.144	15.350	14.773	14.917	0.613	0.541	15.00
M16x1.5	16.00	1.50	0.217	15.026	14.160	14.376	0.920	0.812	14.50
M20x1.0	20.00	1.00	0.144	19.350	18.773	18.917	0.613	0.541	19.00
M20x1.5	20.00	1.50	0.217	19.026	18.160	18.376	0.920	0.812	18.50
M20x2.0	20.00	2.00	0.289	18.701	17.546	17.835	1.227	1.083	18.00
M22x1.0	22.00	1.00	0.144	21.350	20.773	20.917	0.613	0.541	21.00
M22x1.5	22.00	1.50	0.217	21.026	20.160	20.376	0.920	0.812	20.50
M22x2.0	22.00	2.00	0.289	20.701	19.546	19.835	1.227	1.083	20.00
M24x1.0	24.00	1.00	0.144	23.350	22.773	22.917	0.613	0.541	23.00
M24x1.5	24.00	1.50	0.217	23.026	22.160	22.376	0.920	0.812	22.50
M24x2.0	24.00	2.00	0.289	22.701	21.546	21.835	1.227	1.083	22.00
M25x1.0	25.00	1.00	0.144	24.350	23.773	23.917	0.613	0.541	24.00
M25x1.5	25.00	1.50	0.217	24.026	23.160	23.376	0.920	0.812	23.50
M25x2.0	25.00	2.00	0.289	23.701	22.546	22.835	1.227	1.083	23.00
M27x1.0	27.00	1.00	0.144	26.350	25.773	25.917	0.613	0.541	26.00
M27x1.5	27.00	1.50	0.217	26.026	25.160	25.376	0.920	0.812	25.50
M27x2.0	27.00	2.00	0.289	25.701	24.546	24.835	1.227	1.083	25.00
M28x1.0	28.00	1.00	0.144	27.350	26.773	26.917	0.613	0.541	27.00
M28x1.5	28.00	1.50	0.217	27.026	26.160	26.376	0.920	0.812	26.50
M28x2.0	28.00	2.00	0.289	26.701	25.546	25.835	1.227	1.083	26.00