Metric thread calculator to calculate external and internal metric thread dimensions including major diameter, minor diameter, pitch diameter and thread tolerance according to ISO 724 and ISO 965 standards.
There are two calculation options available, general engineering use or custom use.
In general engineering use, calculations can be done by selecting a standard metric thread size in a range from 1.6 mm (M1.6) to 64 mm (M64). Tolerance class can be selected among the alternatives 6e, 6f, 6g and 4h for bolts and 5H, 6H, 7H and 6G for nuts. 6g and 6H are default values and selected class for commercial external threads and internal threads in ISO 965-1:1998. The user shall use 6g for bolts and 6H for nuts unless there is a specific requirement to use other tolerance classes.
In custom use, thread size, pitch and tolerance classes can be independently selected for custom metric thread dimensions calculations.
Some important notes from ISO metric thread standards:
- External Screw Thread Designation: Nominal Diameter x Pitch - Tolerance class for pitch diameter - Tolerance class for major diameter (M10 x 1 5g 6g)
- Internal Screw Thread Designation: – Nominal Diameter x Pitch - Tolerance class for pitch diameter - Tolerance class for minor diameter (M10 x 1 5H 6H)
- If the two class designations for the pitch diameter and crest diameter are the same it is not necessary to repeat the symbols. (M10 x 1 6g)
- According to ISO 1 , standard reference temperature for geometrical product specification is 20 °C.
- Gauges and gauging for ISO general purpose metric threads are defined in the ISO 1502 standard.
- The list of metric screw thread used in general engineering applications are given in the General Purpose Metric Screw Threads Table.
Metric Thread Calculator:
| INPUT PARAMETERS | ||
| Calculation Type | ||
| GENERAL ENGINEERING USE | ||
| Metric Thread | ||
| External Thread (Bolt) Tolerance Class * | ||
| Internal Thread (Nut) Tolerance Class** | ||
| CUSTOM USE | ||
| Nominal Diameter | ||
| Pitch | ||
| Bolt Tolerance Class | ||
| Tolerance | Grades | Deviations |
| Pitch Diameter Tolerance | ||
| Major Diameter Tolerance | ||
| Nut Tolerance Class | ||
| Tolerance | Grades | Deviations |
| Pitch Diameter Tolerance | ||
| Minor Diameter Tolerance | ||
Note : * 6g is normally selected for commercial external (bolt) threads. Use this tolerance class for commercial external (bolt) threads. For usage of the other classes, refer to ISO 965-1:1998.
Note : ** 6H is normally selected for commercial internal (nut) threads. Use this tolerance class for commercial internal threads. For usage of the other classes, refer to ISO 965-1:1998.
| RESULTS | |||
| Parameter | Value | ||
| Note | --- | ||
| Designation | -- | --- | --- |
| Tolerance Class for Bolt | -- | --- | |
| Tolerance Class for Nut | -- | --- | |
| Screw Thread Series | -- | --- | |
| Pitch | P | --- | mm |
| LIMITS OF SIZES FOR EXTERNAL THREADS (BOLTS) | |||
| Maximum Major Diameter | dmax | --- | mm |
| Minimum Major Diameter | dmin | --- | |
| Maximum Pitch Diameter | d2max | --- | |
| Minimum Pitch Diameter | d2min | --- | |
| Maximum Rounded Root Minor Diameter | d3max | --- | |
| Minimum Rounded Root Minor Diameter | d3min | --- | |
| Minimum Root Radii | Rmin | --- | |
| Minimum Truncation | Cmin | --- | |
| Maximum Truncation | Cmax | --- | |
| LIMITS OF SIZES FOR INTERNAL THREADS (NUTS) | |||
| Minimum Major Diameter | Dmin | --- | mm |
| Maximum Pitch Diameter | D2max | --- | |
| Minimum Pitch Diameter | D2min | --- | |
| Maximum Minor Diameter | D1max | --- | |
| Minimum Minor Diameter | D1min | --- | |
| BASIC DIMENSIONS | |||
| Basic Major Diameter | d , D | --- | mm |
| Basic Pitch Diameter | d2 , D2 | --- | |
| Basic Minor Diameter | d1, D1 | --- | |
| Fundamental Triangle Height | H | --- | |
Note-1: For coated threads, the tolerances apply to the parts before coating, unless otherwise stated. After coating, the actual thread profile shall not at any point transgress the maximum material limits for positions h or H. For external (bolt) threads; The actual root contours shall not at any point transgress the basicprofile. Fasteners of property class 8.8 and higher (see ISO 898-1), the root profile shall have a non-reversingcurvature, no portion of which shall have a radius of less than Rmin.
Definitions:
Basic profile: The theoretical profile of a screw thread in an axial plane defined by theoretical dimensions and angles common to internal and external threads
Crest: The surface at the top of the ridge connecting its two flanks.
Gauges and Gauging: Details for themanufacture and use of gauges for checking ISO general-purpose metric screw threads are specified in the ISO 1502:1996 standard. It specifies the features of the types of gauges (Solid/adjustable GO screw ring gauges, check plugs, setting plugs, wear checkplugs, screw caliper gauges, plug gauges, etc.) which are recommended for checkingexternal and internal screw threads of workplaces andfor the setting and checking of certain of the screwgauges.
Major Diameter: The maximum diameter of a thread which is diameter of the crest of a male thread or root of a female thread.
Minor Diameter: The minimum diameter of a thread which is diameter of the root of a male thread or crest of a female thread.
Root: The surface at the bottom of the groove connecting the adjacent flanks
Thread pitch: The distance between two adjacent threads.
Supplements:
- Thread calculators and charts
- Metric thread chart
- Metric thread profile and formulas
Reference:
- Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook
. 30th edition. Industrial Press Inc. - ISO 1:2002 - Geometrical Product Specifications (GPS) - Standard reference temperature for geometrical product specification and verification
- ISO 68-1:1998 (E) - ISO general purpose screw threads — Basic profile — Part 1: Metric screw threads
- ISO 262:1998 (E) - ISO general purpose metric screw threads — Selected sizes for screws, bolts and nuts
- ISO 724:1993 (E) - ISO general-purpose metric screw threads - Basic dimensions
- ISO 965-1:1998 – ISO General Purpose Metric Screw Threads – Tolerances Part-1: Principles and Basic Data
- ISO 965-2:1998 – ISO General Purpose Metric Screw Threads – Tolerances Part-2: Limits of sizes for general purpose external and internal screw threads - Medium quality
- BS 3643-1:2007 – ISO General Purpose Metric Screw Threads – Tolerances Part-1: Principles and Basic Data (British Standard)
. 30th edition. Industrial Press Inc. 