Knitting Increase and Decrease Calculator

In short This is the arithmetic behind an instruction like "increase 6 stitches evenly across 40", and it is the one piece of knitting maths that is genuinely fiddly to do in your head. Six increases across forty stitches works out at one every 6.67 stitches, and you cannot knit two thirds of a stitch — so the row is split into groups that differ by one, four groups of seven and two of six, and written out as "(K7, M1) 4 times, (K6, M1) twice". The test any such instruction has to pass is that the plain stitches add back to exactly the count you started with. Forty in this case, and if a written instruction does not add up, it is wrong; that is the one thing worth checking by hand before you start. Decreases work the same way with one extra step that catches people out: a k2tog consumes two stitches and returns one, so removing six stitches uses twelve of them, and only the remaining twenty-eight get distributed. That is also why you cannot always decrease as much as you want in a single row — removing thirty stitches from forty would need sixty stitches to work, so it has to be spread over more than one row. There is an option to keep the ends of the row plain, which is what published patterns do so that the shaping does not land on a seam edge where it is awkward to sew.