Measure screws correctly

Of course, screws can also be measured. Depending on the type of screw there are small differences. How to measure a screw correctly, we have described here in detail for you.

First, set the type of screw

Screws are available in countless variations. Nevertheless, the screw dimensions are always standardized. However, before you can measure a screw, you must define the type of screw you have. Basically, you can distinguish the following screws:

  • Screws that require a mating thread (usually metric, such as metal screws)
  • Screws that cut the mating thread into the screwed material (wood or sheet metal screws)

Screws that are sunk and not sunk

In addition, a distinction must be made between screws whose head is above the material surface after being put on and which are sunk. Such screws, which can be sunk, are available for all screw types.

Basically, the screw is measured from the tip to the beginning of the screw head. So to the point where the screw shaft ends at the screw head. The exception are countersunk screws. Countersunk screws are measured from the tip or the beginning of the stem with the thread to the top point of the screw head.

This in turn means that even screws that are actually measured without a screw head, must be measured with screw head, if they are still sunk. Because you can not only sink screws that have a countersunk head. In other words, it is always the screw length relevant, which will be screwed into the material or can be screwed.

How to proceed when measuring a screw

You should be able to handle a caliper. In length, the screw is measured by simply clamped between both jaws (countersunk screws). For measuring screws whose head is not measured, it is recommended to use a caliper gauge for inside diameter. This is much easier to set up and the error rate for measurement errors is lower.

Measure the screw diameter correctly

In addition to the length of the screw and the diameter is measured. With metal screws, the key size is important. With hexagon socket head screws, the head of the screw is inserted smoothly into the calliper on two sides of the hexagon. This will give you the key size. Hexagon socket, so Allen, measure with a caliper gauge for inner diameter.

This is how the screw is inserted

When measuring the screw cross-section, the correct insertion into the calliper is also important. Insert the screw lengthways along the thread, lying lengthwise on the two legs of the caliper. If you measure the screw across, the likelihood of measurement errors is very high, as the caliper jaws may slip or tilt between the threads.

Tips & Tricks

The size of a screw is given in millimeters. The exemplary screw size 4 x 80 would therefore be a screw with a diameter of 4 mm and a length of 80mm. With metric screws, the thread is important in addition to the conventional dimensions. The thread pitch can be different (fine and standard thread).

Video Board: How Do You Measure Screws?