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Change the Size of a Knitting Pattern

Kimberly is an enthusiastic knitter who also crochets, teaches knitting, sews, does alterations,and designs/tests knit and crochet patterns.

Make Everything You Knit Fit


Tiny Scarf Knit in the Round


Math for Knitters: Fear Not!

As a knitter with an engineering degree, I recognize knitting as applied mathematics. Combine arithmetic and geometry with yarn and get whatever sizes and shapes you want to create. You need not know calculus, thank goodness, but if you can work percentages and ratios you can scale a knitting pattern up or down in size as needed instead of having to pick a size that doesn't fit perfectly.

Be master of your knitting by using some arithmetic and your gauge swatch (which you knit for every project, right?!) I'll use a scarf as an example, since it is a simple rectangle and the math is very simple. I have knit several Dr. Who reproduction scarves--enormous, monster scarves that overwhelm a small person. I decided I'd like to make a scaled-down version that was more practical for everyday wear, especially for the South, where the warmth of a nine-foot-long, extra-wide scarf is rarely called for.

The Dr. Who scarf is worked in stripes of various widths and the pattern states how many garter ridges (one garter ridge is two rows) in each color band. I wanted my smaller scarf to be 1/2 as wide and 2/3 as long as the larger scarves, so I cast on half the stitches called for in my pattern (20 instead of 40) to begin. The scarf is a stripe pattern with different numbers of garter ridges in each color. If a stripe was 3 ridges wide, I reduced the number of ridges by 1/3, so I knitted 2 ridges instead of 3. For numbers not divisible by 3, I rounded to the nearest multiple of 3, e.g. 10 is closest to 9, so two-thirds of nine is 6 ridges. This is easy mental math for scaling a simple pattern.

Scaling or Sizing More Complicated Projects

Sweaters and Such

Changing length is usually a simple thing to do. Just knit more rows to make longer sleeves or a longer skirt. Changing width can be tricky, however. When changing the number of stitches in a row, make sure you don't interfere with a pattern stitch, e.g. a 4 stitch repeat means you must add or subtract stitches in groups of 4. Also make sure that increases or decreases remain spaced properly around a garment.

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For projects with shaping such as sweaters, I recommend Elizabeth Zimmerman's percentage system, as explained in her excellent book, Knitting Without Tears. There is also a wonderful resource below which gives charts for sweaters in multiple sizes at various gauges--just knit a swatch and find your size on the appropriate chart.

Those with more confidence in their math skills can work out the percentage size reduction and translate that to armhole decreases and other more involved shapes. Proceed at your own risk, though, and be prepared to rip if necessary. Taking frequent measurements as you go or trying on at key junctures can help keep you on track. Be sure to write down what you do so you can do it again if you like the results!

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Please add your comments here:

Jenn Dixon from PA on July 30, 2014:

I'm afraid I usually stick to the patterns. When I try to change anything, bad things happen, and I end up with a misshapen end product.

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