We have tried: Needles are marked with different numbers, depending on their size. You will usually find two numbers on the boxes, for example 70/10; 80/12; 90/14. The first number is the European designation and the second number indicates the numbering, which is mainly used in Asia. In general, the higher the number the needle has, the bigger it is. Another rule is that the thinner the material (fabric), the thinner the needle you need to use. You can also find this specification in the instructions for your sewing machine.