FAQs
Imperial fasteners commonly use thread count, so 20 would represent 20 threads per inch(TPI). Metric fasteners instead specify a thread pitch which is the distance between the threads. Therefore, a 1.5 pitch would have 1.5 millimeters between each thread.
What are the metric thread sizes? ›
Bolt Sizes Chart & Metric Bolt Dimensions
| Thread Size | Major Diameter (mm) | Thread Pitch (mm) |
|---|
| M1.8 | 1.8 | 0.35 |
| M2 | 2.0 | 0.40 |
| M2.2 | 2.2 | 0.45 |
| M2.5 | 2.5 | 0.45 |
36 more rowsMeasuring Imperial Thread Pitch
As the name suggests, TPI is measured by counting the number of thread peaks along a 1-inch length. The TPI measurement is then often affixed to the diameter of the thread to form a common imperial thread size, e.g. '1/4-20', which would denote a ¼ inch diameter and 20 threads per inch.
What are the dimensions of a thread? ›
Threads are measured in threads per inch, or TPI. You simply count the number of thread peaks along a one-inch length. You'll also measure the major diameter of the screw, as shown above. These two measurements will combine to give you the screw size you need.
How to tell the difference between metric threads and standard threads? ›
The metric system for measuring screw threads uses metric units, pitch in millimeters (mm). This is the distance measured between the peaks of two adjacent threads. Whereas, the standard system - the imperial system - measures threads in imperial units by TPI: threads per inch.
Can you mix metric and imperial threads? ›
A setup may combine universal and imperial parts, or it may combine universal and metric parts, but without specialized hardware (such as our threading adapters), imperial and metric parts cannot be combined. Parts designed for metric setups have "/M" or "-EC" at the end of their item number.
How do you read metric threads? ›
M10-1.0 x 20
- M = This designates the fastener is a metric size.
- 10 = The nominal diameter in millimeters.
- 1.0 = The thread pitch, or distance between threads, in millimeters.
- 20 = The fastener's length, in millimeters.
The measurement of an inch nut or bolt will be listed as the thread size — a number between one and 12 or an inch increment followed by the threads per inch (TPI). If the diameter is less than 1/4 inch, the diameter will be listed as a number between zero and 12; the larger the number, the closer it is to 1/4 inch.
Are Whitworth and metric threads the same? ›
Whitworth threads have a steeper flank than metric threads: flank angle 55°, compared to 60° for metric threads. Tapered threads (BSPT) according to DIN EN 10226-1 (formerly DIN 2999) are designated as metallic sealing (R).
What do thread size numbers mean? ›
thread is that a 50/2 thread and a 50/3 thread are different. The first number follows the Gunze Count standard and indicates the thread size. The larger the number, the finer the thread (a 50/2 will be thinner than a 30/2). The second number indicates the number of strands, or plies, twisted together.
TPI stands for Threads Per Inch, a count of the number of threads per inch measured along the length of a fastener. TPI is used only with American fasteners. Metric Fasteners use a thread Pitch. In general, smaller fasteners have finer threads, so the thread count is higher.
What are the most common thread sizes? ›
Common Manufacturer Thread Sizes
- 8-32 = .164" outside diameter, 32 threads per inch.
- 10-32 = .190" outside diameter, 32 threads per inch.
- 1/4"-20 = 1/4" outside diameter, 20 threads per inch.
- 5/16"-18 = 5/16" outside diameter, 18 threads per inch.
- 3/8"-16 = 3/8" outside diameter, 16 threads per inch.
Thread sizes are determined by two main elements: the thread diameter (i.e., the distance between a thread's crests) and the thread per inch (i.e., numbers of threads per inch) or pitch (i.e., the distance between one thread's crest and another).
What is the major and minor dimensions of a thread? ›
Major Diameter: The largest diameter of the thread of the screw or nut. The term “major diameter” replaces the term “outside diameter” as applied to the thread of a screw and also the term “full diameter” as applied to the thread of a nut. Minor Diameter: The smallest diameter of the thread of the screw or nut.
Are metric and imperial threads the same? ›
Metric threads are measured by their pitch. That is the distance from the crest of one thread to the crest of the next measured in millimetres. The pitch of a metric thread can be checked by direct measurement with a metric rule. Imperial threads have their pitch measured indirectly as a given number of teeth per inch.
Is metric thread same as NPT thread? ›
NPT stands for National Pipe Thread and is the US standard for tapered threads for connectors and fittings. NPT threads are usually longer than Metric or PG and taper toward the end. The taper rate for all NPT threads is 1/16. NPT threads are designed to create a liquid-tight seal upon tightening.
How do you identify a metric bolt thread? ›
A screw thread in conformity with this International Standard is designated by the letter M followed by the values of the nominal diameter and of the pitch expressed in millimetres separated by the sign x.
