Quandaries and Queries
Who is asking: Student
Gauge: 3.2 stitches(width) and 4 rows(height) = 1"
Dimensions: 6.25"(width) x 5.25"(height)
Dimensions: 4"(width) x 3"(height)
How do I calculate the percentage change in size to accurately determine the number of stitches and rows needed to produce the desired dimensions for the finished (felted) item?
The complication here is that when you felt, the item shrinks more in one direction than in the other. Using your dimensions you started with a width of 6.25" and, after felting this is 4". 4/6.25 = 0.64 and hence the width after felting is 64% of the width before felting. In the other direction 3/5.25 = 0.57 so the resulting height is only 57% of the starting height. (When you dry your jeans they shrink more in length than in width.)
But you want to go in the other direction, you know the desired dimensions after felting and you want to know the dimensions before felting.
Rows: 5.25/3 = 1.75
Take the number of inches desired in the finished item, in the stitch direction, multiply by 1.56 to get the number of inches required before felting. Multiply this by 3.2 to get the number of stitches to cast on. Take the number of inches desired in the finished item, in the row direction, multiply by 1.75 to get the number of inches required before felting. Multiply this by 4 to get the number of rows to knit.Penny