Ask Anything | Why are pattern gauge and dimensions given for blocked fabric?

I received an interesting message after my post about The Importance of Swatching Your Knits. (Not a member yet? You can watch the lesson for free on YouTube.)

Before I answer, let me touch on one important revelation from the lesson. In knitting patterns, gauge and dimensions are almost always given for fabric that has been washed and dried, a.k.a. blocked. That includes dimensions like "knit until piece measures 5 inches".

Like Tammi's question implies, it would make things easier for knitters if they knew the before-blocking gauge of a pattern so they could just refer to it during the knitting process. It take's time to knit a swatch, measure the before-blocking gauge, wash and dry the swatch, measure the after-blocking gauge, and do the necessary math to find the ratio to convert after-blocking dimensions to work with before-blocking gauge.

If knitters always used the exact same yarn as the pattern designer (and I mean exact same fiber content, same weight, same brand, same color, etc.) one could conceive that if both the designer and knitter had the same before-blocking gauge they would also have the same after-blocking gauge. In reality, knitters don't always use the yarn recommended by the designer. That's perfectly fine. In most cases you'll likely be able to match, or come reasonably close to matching the designer's after-blocking gauge with your choice of yarn and needles. However, your before-blocking gauges could be vastly different than the designer's because different fiber types have different qualities and characteristics and yarns have different constructions. Therefore, yarns will react to water by shrinking, felting, stretching, blooming... in different amounts.

To ensure knitters are able to create a finished garment that is the same size as indicated in a pattern, even if they substitute yarns, gauge and dimensions must be given after blocking because different yarns (and the fabric they create) react to washing and drying in different ways.

If you'd like to learn more about fiber content and yarn construction, I highly recommend "The Knitter's Book of Yarn: The Ultimate Guide to Choosing, Using, and Enjoying Yarn" by Clara Parkes