Knitting wool is a hobby that requires a bit of figuring, especially between U.S. and metric conversions. Needles, patterns, and yarn measurements can be labeled one or the other. This concerns knitting needle size, the thickness of the yarn, and which combination of the two is appropriate for your certain knitting project. Pairing these needle and yarn measurements and using the following chart will help you determine the wraps per inch you should be knitting. Always consult the pattern, if you are using one, and note any considerations if you are using delicate or specialty material.
Needle Size (in diameter)
- 9 to 10 millimeters = yarn labeled over 14 ply = 8 or fewer wraps per inch
- 6 to 6.5 millimeters = 14 ply yarn = 9 to 10 wraps per inch
- 5 to 5.5 millimeters = 12 ply yarn = 10 to 11 wraps per inch
- 4 to 5 millimeters = 10 ply yarn = 12 wraps per inch
- 3.75 to 4 millimeters = 8 ply yarn = 13 wraps per inch
- 3 to 3.75 millimeters = 4 ply yarn = 14 wraps per inch
- 2.75 to 3 millimeters = 3 to 4 ply yarn = 16 wraps per inch
- 1.75 to 2.75 millimeters = 2 to 3 ply yarn = 18 or more wraps per inch
Once paired with the correct needle size, you will also need to determine the correct tension of your stitches. Tension in knitting is defined as the specific number of rows and stitches over each area of your project that measures 10 centimeters square.
- Yarn over 14 ply = 8 to 12 stitches
- 14 ply yarn = 12 to 16 stitches
- 12 ply yarn = 14 to 16 stitches
- 10 ply yarn = 16 to 20 stitches
- 8 ply yarn = 22 stitches
- 4 ply yarn = 20 to 24 stitches
- 3 to 4 ply yarn = 24 to 28 stitches
- 2 to 3 ply yarn = 28 to 32 stitches
If you are not sure what the ply of your yarn is, you can determine this by counting wraps per inch. Wraps per inch can best be described as the number of times you are able to wrap your yarn around one inch of a ruler. If at all possible, keep a ruler with both inches and centimeters with the rest of your knitting supplies. The size and width of the ruler does not matter as long as you are using this method to measure the width of your yarn rather than its length.
Helpful Metric Conversions
- 1 inch = 25.4 millimeters
- 1 inch = 2.54 centimeters
- 1 centimeter = 10 millimeters
- 1 millimeter = 0.04 inches
- 10 millimeters = 0.39 inches
- 10 inches = 25.4 centimeters
- 10 inches = 254 millimeters
- 10 centimeters = 100 millimeters
- 20 inches = 50.8 centimeters
- 20 inches = 508 millimeters
- 20 centimeters = 200 millimeters
Using some examples from the needle size chart above, a 6 millimeter needle measures 0.24 inches around, a 10 millimeter needle measures 0.39 inches, and so forth.