Adding Length to Sweaters

If I find jumpers I like that are not the length I want, I regularly adapt them. Not every garment is easy to lengthen, especially if there is waist shaping or a complicated textured or colour work pattern, but

where the sides of the body are straight, and the design fairly plain, it can work just fine. It does, however, beg the question, 'How do I know how much extra yarn I will need if I want to add a certain length to my garment?'

I am currently working on Blueprint by Joan Forgione in Manos Milo. This is another cropped design but I have decided to add an extra 4 inches to the body length.

What I need to know is, 'Will I have enough yarn to do this or will I need to get an extra skein?'

The key to this calculation is my gauge swatch.

  • My gauge, measured from my swatch, is 23 stitches x 36 rows per 4 inches (10cm).

  • At this gauge my extra 4 inches of body will mean an extra 36 rounds, each being 253 stitches which means 36 x 253 = 9108 extra stitches in total.

  • My whole swatch is 36 stitches x 42 rows making a total of 1512 stitches.

  • This swatch weighs 6g.

  • This means my extra 4 inches will weigh (9108 ÷ 1512) x 6 = 36.14g

  • I'll round this up to 40g to allow for a margin of error.

  • My yarn has 350m per 100g so I can also convert the requirement into metres: 350 x 0.4 = 140m

  • I have 3 skeins = 1050m to make a size that requires 758m which leaves me 292m spare.

  • I have enough!

This does, of course, assume that you have already got your yarn to swatch with and weigh at the outset (and some reasonably accurate digital scales). But it may at least enable you to work out at the start of a project whether you can make it the length you want and get more supplies promptly if not.

Judith Goodfellow