Question 1

What sizes do screws come in?

Accepted Answer

Screws come in a wide range of sizes, mainly measured by diameter, length, and thread type. Diameters can range from as small as 2mm up to about 12mm for general construction use. Lengths vary significantly, usually between 30mm and 150mm, though specialised screws may be longer.

Specific screw sizes also depend on the intended use, such as woodworking, metalwork, drylining, or structural framing. In the UK screw sizes are normally measured in mm, although metric sizes do pop up occasionally.

Buildbuddy lists a wide variety of popular screw sizes and diameters, from M3 and M4 right up to M12 diameter screw sets, as well as from 30 to 200mm in length.

Question 2

How do I measure screw size?

Accepted Answer

To measure screw size accurately, use a calliper or a precise ruler. Measure the diameter at the widest point of the threaded section. Length is measured from the underside of the screw head down to the tip. For countersunk screws, measure length from the top of the head to the tip.

Question 3

What are screws made of?

Accepted Answer

Screws are typically made from steel, stainless steel, brass, or zinc-coated metals. Steel screws are common due to their strength and durability, often zinc-plated to resist corrosion. Stainless steel screws offer greater corrosion resistance, suitable for outdoor or damp environments. Brass screws are softer, making them suitable for decorative work or delicate materials. The material you need will depend on the project requirements and conditions on-site.

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