What does 8.8 mean on the head of a bolt?
If you have ever looked a metric hex bolt you might notice the markings 8.8, 10.9 or 12.9 this does not mean grade 8,10 or 12. The grade 8.8 refers to the tensile strength which is generally 116,000 psi, grade 10.9 is generally 150,000 and grade 12.9 is generally 175,000 psi.
|Tap size||Basic major dia (mm)||Basic major dia (inch)|
|M6 x 1||6mm||.2362|
|M8 x 1.25||8mm||.3150|
|M8 x 1||8mm||.3150|
|M10 x 1.5||10mm||.3937|
- The M8 will measure about 8 mm in diameter, more likely, just a touch undersize, (.31496") The M10, about 10 mm in diameter, (.3937") and the M12 about 12 mm in diameter, (.4724"). The "M" designates the bolt is Metric and the number after the M indicates the size. The number after that is the length.
- The Flat Display Mounting Interface (FDMI), also known as VESA Mounting Interface Standard (MIS) or colloquially as VESA mount, is a family of standards defined by the Video Electronics Standards Association for mounting flat panel monitors, televisions, and other displays to stands or wall mounts.
- The actual diameter of an M3 screw is usually about 2.9mm, an M2.5 screw is 2.4mm and an M2 is 1.9mm. We give both the overall length and the thread length. The clickable size given in the menu on the left is the thread length in the case of pan head and oem wafer head but the overall length for the flat head screws.
Inch Threads vs. Metric Threads
|Inch Bolts||Metric Nuts|
|5/16″-18||M8 x 1.0|
|3/8″-16||M10 x 1.5|
|7/16″-14||M12 x 1.75|
|1/2″-13||M14 x 2|
- The "8" refers to the size (diameter) of the screw, and the "32" means it has 32 threads to the inch. The diameter is measured at the shank of the screw. Screws are sized by gauge number and length. For example, an 8 gauge screw with 32 threads per inch and 1" in length would be written as: 8-32 X 1".
- Screws have three basic measurements: gauge, threads per inch, and shaft length in inches. So, you may also see a measurement like 6-32 x 1 1/2". This means it's a #6 diameter, with 32 threads per inch (almost double the normal thread count as a standard wood screw) and an inch and a half long.
To Tap This Size Screw Or Bolt: Use This Drill Bit: (Closest Fractional:) 10-32 NF #21 5/32" 5mm-0.90mm 4.2mm - 5mm-0.80mm 4.3mm - 12-24 NC #16 11/64"
Diameter is in either Inches ( not decimal ) or Millimeter. Second measure the pitch Pitch is threads / per unit. Inches are measured threads per inches. Third measure length Length is measured from behind the head to end, ( except for flathead is measured total length ) .
- M 10 x 1.5 is a metric bolt with a 10 mm nominal diameter and 1.5 mm pitch. The standard American bolt is defined by the inch system designation. For both metric and standard bolts, the head size is the distance across the flats. For standard bolts, the head size is measured in inches or fractions of an inch.
- Hex key standard sizes. Hex keys are measured across-flats (AF), which is the distance between two opposite (parallel) flat sides of the key.
- PITCH-This is the distance from a point on the screw thread to a corresponding point on the next thread measured parallel to the axis of the thread. It is represented by the letter p. (p=1/n). MAJOR DIAMETER- This is the largest diameter of the screw or nut.
Updated: 2nd October 2019