Usually crochet hooks or needles are made of materials like wood, plastic, bone, stainless-steel, aluminum, or tortoise-shell. If they are constructed with such fabricating materials, they act as a stiff support to conduct all the heavy crocheting work with wools and cotton threads. When you consider a crochet project, along with the hook sizes, the built of the hooks is also taken into consideration. For instance, the sharpness of its points, the finesse of the rods, the back curve, handles, etc.
Generally, crochet hook sizes have a very universal marking. The sizes are coined into the hook itself. For instance, if the hook has a letter 'N'; that stands for America. This way there are many determining systems which are based on the letters and number systems. In the US, sizes are determined by numbers and letters. In Europe it's the physical metric system. Aluminum and steel crochet hooks have a standard-clear marking engraved into the hooks. They are broadly measured by the thickness of the needle, and the sizes are measured in millimeters or inch systems. Practically, manufacturers create hooks depending on the country, the age of the patterns, and also the brand.
|European Metric||US size||UK size|
|17 ½ mm||R||-|
In this manner, there are many hook sizes and equivalents that exist, and are also available on the Internet. The hooks that are obtainable in B - K and N sizes are usually aluminum fabricated. Any hook size which is larger than N is made of plastic. As mentioned earlier, the sizes chiefly and variably differ in accordance to a country too. Supposing an Australian would want a size 2, if you consider being in any other country say US or Europe, it wouldn't be of the same size.
The conversion chart tabled above is a very helpful way to comprehend the conversions from Metric to UK to US sizes for aluminum hooks. Hook sizes are supposed to jibe with the thread's thickness. If the yarn is thicker, it naturally would need thicker hooks. Normally, sizes range from the lowest figure, i.e., 0.60 mm right up to 25.0 mm. Smaller hooks are marked with numbers, not letters. They are the steel hooks. Steel crochet hooks are practiced for fine yarns and thread crochet. Something with cobweb yarns, lace weight, or bead crochet. Here is a table below, which will give you the conversions.
|Metric (mm)||US size||Canadian/UK size|
The next category that comes in crochet hooks is the yarn size hooks, often found in plastic forms. They are best suited for the beginners to begin with. For professionals, aluminum or metal hooks are ideal. The most famous ones are Susan Bates and Boye (Wrights) that are easily available in craft stores. For an untrained eye, all the hook sizes may look the same. But for a fervent knitter, running through a variety of them may get overwhelming. The best option is to depend on the kind of crochet work you do. That's when you would be able to decide with your pick.