Buy the yarn you like and use the needle size you like with this easy to use Calc O Knit. Math's a snap when you use your CALC-O-KNIT to make or change knitting patterns. All the calculations have been done for you. Set your stitch and row gauge there are 34 different gauges in the stitch gauge window. All calculations from 1 to 50 inches are immediately available to you. You will be amazed how easy this works without buying an expensive computer program.