metric thread size chart

Downloads The coarse pitch is the commonly used default pitch for a given diameter. Thermodynamics Vibration Engineering <> M500 6g in external threads). 15.0. ANSI/ASME B1.13M-1995. Metric Thread Conversion Table | Optimas ISO Metric Thread Defaults: Pitch - According to the Coarse pitch series. All units in mm. Heat Transfer 0000026129 00000 n 0000019519 00000 n METRIC THREAD - Drill & Tap Chart - shender4.com You can target the Engineering ToolBox by using AdWords Managed Placements. Dared, Jamnagar, Gujarat, India. Threads produced to this standard are interchangeable with threads produced to the metric standard ANSI/ASME B1.13M Metric Screw Threads: M Profile. Here are two imperial thread sizes table defines thread dimensions of coarse threads (UNC/UNRC) and fine threads (UNF/UNRF). Apollo International is the leading manufacturer and exporter of Brass, Copper & Other Metal Components in India. Nominal Size ISO MF. Welding Stress Calculations Mechanical Tolerances Specs The tolerances TD for internal threads and Td for external threads is derived from the class. | CNCLATHING, What is Thread Milling & How Does a Thread Mill Work | How to Thread Mill | CNCLATHING, List of Drill Bit and Tap Sizes Drill Size Chart and Tap Size Chart | CNCLATHING, What is NPT Thread & NPT Thread Dimensions NPT Thread Size Chart | CNCLATHING, Machine Screw Diameters Chart and Unified National Thread Sizes What is a Machine Screw | CNCLATHING, Rivet Hole Size Chart & How to Determine the Rivet Size | CNCLATHING. The designation of a screw thread gives the thread symbol, the nominal size, the pitch, and the thread tolerance class (Ex: M6 x 1 - 4g6g). When the diameter smaller than 1/4, the value is indicated by a number, like #1 or No.1. Structural Shapes Threads are called out by O.D. Note that the ISO 724 standard specifies threads up to M 300. It was one of the first topics standardized by the ISO committee as early as 1947 and is still used today. x[7r;@/,V7k K }A INFf:""_/|e_Q\4lh9\)uxO~~yoo/^~yw{)/??>}{9]/^*_?[0\u$LM|~g5UdMBjq,FOm;9CmBe^bEa) j_WcuSC!ly-_l_|}m>7=MGYk~Nu;{9*GUiX=0MdTuT/]l+EG3]>~}mDFN5A7!?&J^bhn3{s}bjhi%f&1itO5>meKNbN-Fw1u{q!O{|)l/YfO._+.mkx>~w*]lL2:/a>r(`{D#9aMFm[a%HJLJzQ$Fh{kX&'q9Pva^Y$3Ll]IXamEx;Jf#J|, |by6dU\bO:,0TyVQqdb_MnU6'@OFA!Vm8SjqDSFI{.^M``KYyl3A9EJh@2S ! In practice this means that one can measure the diameter over the threads of a bolt to find the nominal diameter Dmaj, and the inner diameter of a nut is Dmin. Finishing and Plating ISO 724 specifies basic dimensions of metric threads in accordance with ISO 261. Superfine pitch metric threads are occasionally used in automotive components, such as suspension struts, and are commonly used in the aviation manufacturing industry. 1 0 obj 20 0 obj <> endobj Major Diameter mm d=D. Some of our calculators and applications let you save application data to your local computer. Metric fasteners are specified with a thread pitch, instead of a thread count. Metric thread specifications are different because . H = P ( 31/2 / 2 ) = 0.866025 P United Inch Screw Threads Per ASME B1.1. Metric Thread Pitch Table| Metric Thread Sizes www.NewportFasteners.com ANSI/ASME B1.13M-1995. 0 | Difference Between UNF and UNC Thread | CNCLATHING, Guide to Design and Machining Thread: How to Cut an Internal & External Thread? While a ruler could be used to calculate the pitch size, a pitch gauge is highly . PDF Metric Thread -- Extended Thread Size Range The 1st choice column follows the R10 series from ISO 3, while the 2nd choice column is rounded off values from the R20 series from ISO 3. Let us take an example now - a 3/8-16 (coarse) thread size has a 3/8" nominal major diameter and 16 thread per . ISO metric screw thread - Wikipedia In all other cases, calculations must be made manually according to the below formulas or by our Threading Calculator, * For threads over 1.4 mm and classes 5H & 6h for threads up to and including 1.4 mm. Thread Pitch in mm Coarse Fine THREAD SIZE COMPARISON CHART Dia. These thread sizes and classes represent bolts and screws, as well, as other standard internal threads. For example, for M8 X 0.75 5g6g, the class is 5g6g. TPI stands for Threads Per Inch, which means the total number of threads per inch measured along the length of a fastener. 0000019082 00000 n A table to help find the nearest sized metric coarse, metric fine, BSF, BNW, UNC and UNF fasteners. Two charters long class mean that the class is valid for both the pitch and major/minor diameters. <> That is, an M6 screw has a nominal outer diameter of 6 millimetres and will therefore be a well-located, co-axial fit in a hole drilled to 6mm diameter. Engineering Standards External Metric Thread Table Chart Fastener Sizes M 0.25 - Engineers Edge (adsbygoogle = window.adsbygoogle || []).push({}); Copyright 2000 - <>/OutputIntents[<>] /Metadata 1646 0 R/ViewerPreferences 1647 0 R>> ). <> The allowance EL for internal threads and es for external threads is derived from the class. M16 x 1. Section Properties Apps A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter) and the pitch P, both expressed in millimetres and separated by the multiplication sign, (e.g. Videos Design Manufacture %%EOF Materials and Specifications Spring Design Apps Economics Engineering | Contact, Home The metric thread sizes are different from the inch thread sizes. Bolt Depot - Printable Fastener Tools ISO 261 specifies a detailed list of preferred combinations of outer diameter and pitch for ISO metric screw threads. - 361006, Email: apollointnl@gmail.com These applications will - due to browser restrictions - send data between your browser and our server. Excel App. Number of Starts - One. AddThis use cookies for handling links to social media. Cells with Golden Background - Values are derived from the above defaults. Cookies are only used in the browser to improve user experience. For example, an M10x1.5 (coarse) thread has a 1.5mm pitch, while an M10x1.25 (fine) thread has a 1.25mm pitch. 1 mm = 0.039 inches Metric Bolts - Proof Loads Measure screw diameter, or screw size, by measuring the width of the threaded part of the screw. The Metric thread standard ISO 965-2 provides the limits only for classes 6H & 6g*. Figure 1 Basic profile of ISO metric thread 1 Figure 2 Basic dimensions 6 Figure 3 Tolerance positions with respect to zero line (basic size) 15 . The "M" designation for metric screws indicates the nominal outer diameter of the screw thread, in millimetres. d3. This is because extra fine threads are more resistant to coming loose from vibrations. Do not use these values for standard metric internal thread design. If you don't know the pitch, choose coarse threads; they're the industry standard. Coarse Thread Sizes Fine Thread Sizes Important: Ensure that "Actual size" (no page scaling) is selected when . Design & Manufacturability Plot No. Definitions of terms are located below the chart. 0000023239 00000 n M81.2530 or M830). How to ID Metric Threads | Adaptall Physics The first number after the letter M is the screw diameter which equals 3 mm. Feedback Advertising You case use them directly, utilize our ThreadCalculator[ , or browse the below charts. 0000010391 00000 n These thread sizes and classes represent bolts and screws, as well, as other standard external threads. pitch. If the class is omitted, the default class is used. Friction Engineering All units in mm. <> In tolerance class designation, the pitch diameter tolerance is followed by major diameter tolerance. Siz e Gau ge Si e ge BRITISH No. Training Online Engineering, Fastener and Screw / Bolt Design, Formula and Calculations, Length of Screw Thread Engagement per. Pumps Applications 2023, by Engineers Edge, LLC www.engineersedge.com If you don't know the pitch, choose coarse threads; they're the industry standard. <> <> Dimensions refer to the basic profile in accordance with ISO 68. endobj These are the M Profile limiting Dimensionings. This corresponds to the second number of the thread size. Metric Screw Size Chart - Guide with Complete Dimensions ), for this chart you can just drop the 'M' from the front and add an extra at the back (M3 = 3mm, M4 = 4mm. Machine Design Apps on a bolt) will pass through easily to create a well-located connection to an internally threaded component (e.g. The basic dimensions are nominal dimensions of a metric thread profile without allowance and tolerances (The thread class defines that). (See above table). ISO Pipe Thread and Port Thread Sizes - Womack Machine Supply Company [2] Each thread is characterized by its major diameter, D(Dmajin the diagram), and its pitch, P. ISO metric threads consist of a symmetric V-shaped thread. 0000001991 00000 n Videos Design Manufacture startxref xref ANSI/ASME B1.13M-1995. Design & Manufacturability Engineering Book Store Unified Screw Threads (UNC/UNF/UNEF): Charts & Formulas - Machining Doctor This data can be found in ISO 951-1 or in the Limits and Dimensions section below. The relationship between the height H and the pitch P is found using the following equation where is half the included angle of the thread, in this case 30:[3]. Only emails and answers are saved in our archive. . Hydraulics Pneumatics In the plane of the thread axis, the flanks of the V have an angle of 60 to each other. %PDF-1.7 % Gears Design Engineering Tables of the derived dimensions for screw diameters and pitches defined in ISO 261 are given in ISO 724. [7], The thread values are derived from rounded Renard series. In the ISO metric system a decimal point is made with a comma instead of a period. An example of data being processed may be a unique identifier stored in a cookie. All units in mm. Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! $ \large T_d(6) \approx 180\times\sqrt[3]{P^{2}}-\frac{31.5}{\sqrt{P}} $, $ \large T_{D1}(6) \approx 433 \times P 190 \times P^{1.22} $, Major (Basic) diameter of internal thread, Major (Basic) diameter of external thread, Minor diameter for external thread root limits, Designation for thread engagement group "Short" / "Medium" / "Long", DIN / SAE / AISI / Wnr / UNS / BS / ANFOR / UNI / UNS / JS. The thread pitch is the distance between each thread in mm. METRIC INTERNAL THREAD DIMENSIONS CHART - Amesweb Tolerances should be considered when designing products. Diameter is also known M6 small series flange bolts have 8mm hexagonal heads, as would normally be found on M5 bolts).[9]. Friction Engineering 1) For metric threads pitch is the distance between threads. Manufacturing Processes We still do not know however if it is 1.0 or 1.5 thread pitch (or some other pitch). The following table chart are standard metric internal thread sizes M 0.25 - M 8 per. Section Properties Apps Physics PDF ISO metric screw threads - Lawrence Berkeley National Laboratory . <> ISO Metric Coarse And Fine Thread Dimensions | Optimas All units in mm. our selection of screws. H = P ( 31/2 / 2 ) = 0.866025 P or 0.125H = 0.108253P. , Continue with Recommended Cookies, * Easy access to all the data charts that appear on this page. Metric thread sizes are specified by diameter and pitch, which is the space between The formal values must be obtained from ISO 965-1 or from the below chart. To view Metric translation click the Thread Link UNEF Series Basic Dimensions chart Beam Deflections and Stress Learn how and when to remove this template message, International Organization for Standardization, Preferred metric sizes ISO_261 and 262 fastener diameters, Diagrams and tables of many screwthread series. The table below is not complete. 0000013841 00000 n 0000018204 00000 n 'RoZW(kN-9:3:WO\&:s4t.uZ$uC:[D,IWW0[VvM^nNJoK5]=\&ZhAwo- The designation of a screw thread gives the thread symbol, the nominal size, the pitch, and the thread tolerance class (Ex: M6 x 1 - 5H6H). Thread Sizes (Dimensions) Explained Imperial & Metric Thread Sizes Chart | CNCLATHING, Thread Types, Terms, Designation, and How to Identify & Measure Threads | CNCLATHING, Bolts Types and Sizes: Metric & Imperial Bolt Dimensions Chart | CNCLATHING, What are UNF Threads and UNC Threads? The class is written after the pitch. of 12 mm and a pitch of 1-1/2 mm. Strength of Materials The ISO Standardisation Authority defines strict specifications metric threads. endobj 8 0 obj However, here's a quick overview from the chart: The M2 screw size has a diameter of 1/16 inch. Blue Background Default ClassesGreen Background First Choice Classes.Yello Background Second Choice Classes. 0000023992 00000 n M8). Once the Td, TD, es & EL values are known the final limits can be calculated according to the below formulas. (Valid above 1.6 mm / 0.063) Direction - Right-hand thread. Civil Engineering Understanding Inch & Metric Thread Callouts. <> ASME B1.1 M10 x 0.75. [5][6] ISO 262 specifies a shorter list of thread dimensions a subset of ISO 261. A thread's pitch size is the number of threads per inch or the distance between threads on metric thread types. in a nut), the major and minor diameters are minimum dimensions; therefore the thread profile must end flat at Dmin but may be rounded out beyond Dmaj. Metric fasteners are specified with a thread pitch, instead of a thread count. Engineering Mathematics If the pitch is the normally used "coarse" pitch listed in ISO 261 or ISO 262, it can be omitted (e.g. f[rTw*b]w}5gxs:2S9G3@nx= O8~bS{dIh`nl. Machine Design Apps In internal thread tolerance class designation, the pitch diameter tolerance is followed by minor diameter tolerance. threads. The pitch varies from coarse to extra fine with up to 5 different pitches for some dimensions. Metric Fasteners use a thread Pitch. Electric Motor Alternators 0000003684 00000 n ISO 261: ISO general purpose metric screw threads General plan. [citation needed], Tolerance classes defined in ISO 965-1 can be appended to these designations, if required (e.g. <>>> endobj 11 0 obj METRIC BOLT SIZE CHART - Stud Bolt to Nut Size Chart Metric Stud Bolt To Nut Size Chart Our metric stud bolt to nut table is meant to help determine the correct size bolt or nut for your purpose. BA threads are used for sizes under 1/8 inch the older British fastener system. The design principles of ISO general-purpose metric screw threads ("M" series threads) are defined in international standard ISO 68-1. Lubrication Data Apps All rights reservedDisclaimer | endobj 9 0 obj For example, a 1/4-20 (UNC coarse) thread has a 1/4" nominal major diameter and 20 threads per inch, while a 1/4-28 (UNF fine) thread has the same nominal major diameter but 28 threads per inch. <> The following table chart are standard metric internal thread sizes M 0.25 - M 8 per. Here is the metric thread sizes table defines standard metric external thread size M1.6 to M18 per. Threads & Torque Calcs 0000002104 00000 n Lubrication Data Apps All dimensions are in inches. 22.5. For guidance only. METRIC THREAD - Drill & Tap Chart Coarse Thread Sizes. Manage Settings The consent submitted will only be used for data processing originating from this website. In addition to coarse and fine threads, there is another division of extra fine, or superfine threads, with a very fine pitch thread. For example, a caliper reading of 12.03mm indicates it is very likely a 12mm thread. To understand classes, you first need to understand the terms Allowance (Sometimes referred to as deviation) and Tolerances. Welding Stress Calculations For metric screws, this is the length in millimeters between threads. on a bolt), the major diameter Dmaj and the minor diameter Dmin define maximum dimensions of the thread. Coarse pitch . ISO 262 "ISO general purpose metric screw threads Selected sizes for screws, bolts and nuts", has not been included as a separate clause in this standard as . Flat Plate Stress Calcs The below video provides a short explanation of the threading terms. 8 corresponds to 0.164"). The class defines the Deviation (allowance) and tolerance of the thread. There are two common methods to write the thread dimensions. Measure thread spacing. These are the M Profile limiting Dimensionings. The basic dimensions can be used for design. <> Download and print metric coarce threads clearance and tap drill chart. For example, a 10-24 screw has 0.190" thread diameter and has 23 threads per inch. Junying Metal Manufacturing has developed high-level manufacturing technique in The M5 screw size has a diameter of 1/8 inch. Tap Chart Metric Threads - Carbide Depot M6 corresponds to 6 mm). We have discussed the basic thread terms including thread diameters, crest, root and more definitions in the last article. UNEF - Ultra Fine pitch thread. ISO 965-3: Deviations for constructional screw threads, ISO 965-4: Limits of sizes for hot-dip galvanized external screw threads to mate with internal screw threads tapped with tolerance position H or G after galvanizing, ISO 965-5: Limits of sizes for internal screw threads to mate with hot-dip galvanized external screw threads with maximum size of tolerance position h before galvanizing, This page was last edited on 5 February 2023, at 23:22. Small letters represent external threads, while capital letters represent internal threads. The approximate allowance can be calculated according to the below formulas: Unfortunately the above formulas are approximations only. Thread Size: Tap Drill (mm) Thread Size: Tap Drill (mm) Thread Size: Tap Drill (mm) M4 x 0.35. In general, smaller fasteners have finer threads, so they have a lower thread pitch. Metric Internal Thread Chart Limiting Dimensions for M Profile: Thread . External Metric Thread Table Chart and Fastener Sizes M1.6 - M18 Training Online Engineering, Fastener and Screw / Bolt Design, Formula and Calculations, Length of Screw Thread Engagement per. The outermost .mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}18 and the innermost 14 of the height H of the V-shape are cut off from the profile. Please read AddThis Privacy for more information. Google use cookies for serving our ads and handling visitor statistics. These thread sizes and classes represent bolts and screws, as well, as other standard internal threads. endobj The design principles of ISO general-purpose metric screw threads ("M" series threads) are defined in international standard ISO 68-1. For example, a M6 x 1 mm has a 6 mm thread diameter and has 1 mm between threads. Gears Design Engineering Where: H = P ( 3 1/2 / 2 ) = 0.866025 P or Tap size: Basic major dia (mm) Basic major dia (inch) mm per thread: Drill size (mm) Drill size (inch) It is preceded by a and consists of two or four characters. They are based on standard ISO 68-1. hb```b``b,ka!n`@W2:^5JR;~lu}snKsk~8Uv}XC+: !4%,F8 i V(300aG"YK:pD\c\u %KYI. Where: H = P ( 3 1/2 / 2 ) = 0.866025 P or Our smart WIZARD shows you the BEST GRADE by each brand for your application! 0000025364 00000 n 2.Thread sizes in metric are specified by diameter and pitch. Other (usually smaller) sizes may occur to reduce weight or cost, including the small series flange bolts defined in ISO 4162 which typically have hexagonal head sizes corresponding to the smaller 1st choice thread size (eg. ANSI External Screw Threads Size Tolerances Chart - Engineers Edge Engineering Book Store The thread pitch is the distance between threads expressed in millimeters. production fields of machining. 0000007146 00000 n 0000004109 00000 n Hardware, Metric, ISO 2 0 obj 0000023618 00000 n Metric Thread: Metric is one of the first internationally agreed general-purpose thread types. 0000030459 00000 n It is common to designate metric fine threads with the capital M plus an indication to their nominal outer diameter and their pitch: The table below indicates the typically used finer threads up to size M 100. However, ISO 965-1 recommends limiting the choice according to a chart of Recommended Classes. Structural Shapes All units in inches. [2] Each thread is characterized by its major diameter, D (Dmaj in the diagram), and its pitch, P. ISO metric threads consist of a symmetric V-shaped thread. ISO Hardware Engineering Data Metric to US Conversion Table for common fastener sizes - Monster Bolts Some of our partners may process your data as a part of their legitimate business interest without asking for consent. View our thread pitch chart here to get more ideas about different thread sizes. %PDF-1.7 threads in thin-walled pipes). Power Transmission Tech. Superfine pitch metric threads are occasionally used in automotive components, such as suspension struts, and are commonly used in the aviation manufacturing industry. endobj 5 0 obj 0000001956 00000 n Please read Google Privacy & Terms for more information about how you can control adserving and the information collected. Note that the ISO 724 standard specifies threads up to M 300. Electric Motor Alternators Metric Fine Threads Chart - Boltport Fasteners 0000018619 00000 n Internal Metric Thread and Fastener Sizes M 9 - M 24 - Engineers Edge a nut) on the other side. trailer 9.0. ISO 262 specifies a shorter list of thread dimensions - a subset of ISO 261. Manufacturing Processes PDF Thread Size Comparison Chart - Spaenaur In general, smaller fasteners have finer threads, so the thread count is higher. Several ISO standards define together the ISO metric thread system: The description always begins with a capitalM, followed by thenominal thread diameterin millimeters. % stream Metric thread marks: M20-6H, M201.5LH-6g-40, where M means metric common thread, 20 means the nominal diameter of the thread is 20mm, 1.5 means the pitch, LH means left-handed, 6H, 6g means the thread accuracy grade, The uppercase precision grade code represents the internal thread, the lowercase precision grade code represents the external Pressure Vessel .com Inch and Metric Pouce et Mtrique Thread Size Comparison Chart R8 Comparisons . How to Measure Screw Thread Size | McMaster-Carr HVAC Systems Calcs This is to ensure compatibility with mating components. Applications and Design Hardware, Imperial, Inch 0000006324 00000 n endobj 10 0 obj Fastener and Screw / Bolt Design, Formula and Calculations. For those with a diameter smaller than 1/4", screw size is indicated by a xms$+B OO The V-shaped thread form has a 60 flank angle and male and female threads are both parallel. The following table chart are standard metric internal thread sizes M 9 - M 24 per. The following table chart are standard metric external thread sizes M 0.25 - M 1.4 per. [ 13 0 R] Do not use these values for standard metric external thread design. [4]:17, The length of a machine screw or bolt is indicated by a following and the length expressed in millimetres (e.g. If you are looking for Brass, Copper & Other Metal Components manufacturers? The thread angle is 60o and the thread depth is 0.614 x pitch. In general, smaller fasteners have finer threads, so they have a lower thread pitch. HVAC Systems Calcs 9.25. UNC - Coarse Putch thread. These thread sizes and classes represent bolts and screws, as well, as other standard external threads. 0000025028 00000 n Thermodynamics Electronics Instrumentation The table below is not complete. The M6 screw size has a diameter of 9/64 inches. Skip to content. To view Inch translation click the Thread Link, To manufacture or measure a thread, one has to know the maximum and minimum permissible values of the basic dimensions. <>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 11 0 R 12 0 R 15 0 R 24 0 R] /MediaBox[ 0 0 612 792] /Contents 4 0 R/StructParents 0>> 0000004531 00000 n 4 0 obj endobj 13 0 obj <> The values are calculated from the definitions of ISO 965-1. Economics Engineering Vibration Engineering UNF - Fine pitch thread. These thread sizes and classes represent bolts and screws, as well, as other standard external threads. Thread Sizes (Dimensions) Explained - Imperial & Metric Thread Sizes Beam Deflections and Stress 0000005898 00000 n ANSI/ASME B1.13M-1995. ISO 965-2: Limits of sizes for general purpose external and internal screw threads. All units in mm. The clearance drill sizes listed are the most commonly used sizes. endobj 14 0 obj For instance, when a screw or bolt measures 5.9mm, it is called a 6mm thread. Flat Plate Stress Calcs Thread sizes are not directly interchangeable. The minor diameter Dmin and effective pitch diameter Dp are derived from the major diameter and pitch as. 0000011192 00000 n oo^>~/o^}u~zw7y|sy>:|'?t;w~W~3u0it\LNg}{c>/W;|??hV8]ECe~AM?,{}y q4C? ISO 965-1 Calculator, Internal Metric Thread and Fastener Sizes M 9 - M 24, Internal Metric Thread and Fastener Sizes M 24 - M 50, Internal Metric Thread and Fastener Sizes M52 - M72, Internal Metric Thread and Fastener Sizes M75 - M120, Internal Metric Thread and Fastener Sizes M125 - M180, Internal Metric Thread and Fastener Sizes M185 - M230, Internal Metric Thread and Fastener Sizes M235 - M600. It indicates the diameter of smooth-walled hole that a male thread (e.g. PDF Product Table Metric Thread Size Chart - LEXCO CABLE The thread pitch is the distance between threads expressed in millimeters. Thread Form Type. ASME B1.1 Inch Size UN External Screw Threads Formulas and Calculator per. endobj 7 0 obj PDF Metric Screw Thread Chart - Best Materials endobj Heat Transfer Note - Metric screw diameters usually start with "M" (M3, M4, M5. In this guide, we demonstrate how to measure screw thread size for inch and metric systems of measurement. For metric screws, this is the number of millimeters preceded by the letter M Civil Engineering Here well focus on the thread dimensions explain and the standard imperial/metric thread sizes chart. 2023, by Engineers Edge, LLC www.engineersedge.com Pitch mm p. Root Radius mm r. Pitch Diameter mm d2=D2.