screw label numbers

What Do All the Numbers Mean?

Did you ever read the label and wonder what all the numbers represented? Well, here’s your decoder ring!

Example: 12-24 X 7/8 Hex Washer Head Self Drilling #3 Drill Bit

12 – Represents the thickness of the shank. Think dress size. The bigger the number, the thicker the shank.

24 – Represents the number of Threads per Inch also known as TPI. The higher the number, the finer the threads, which are best used in metal applications. The fewer the threads per inch, the coarser the threads, the faster the screw will drive and are the preferred threading for wood applications or wood studs.

7/8 – measurement from underneath the head to the tip of the screw. In the case of flat headed screws, the length is measured from the top of the screw to the point.

#3 Drill Bit – Drill bit tips range from #2 to #5. They do not represent the size of the hole that they will drill but do represent the thickness of metal they will drive through. But we will save that for another tip!