Ahem…please consider this a demonstration of why you need to swatch to figure out your needle size. A friend and I knit these swatches on the Exact Same Needles from different colors of the Exact Same Yarn, and look at the difference in the gauge.

The yarn label says “Needle Size 3mm (US 2-3), 28sts to 36 rows = 10cm square” (that’s 7 stitches and 9 rows per inch for those of us who think in inches). We both used the exact same US size 2/3mm needles (not just the same size, the actual same needles from the same set of DPNs).

Mine is coming in at 4.75 stitches and 7.5 rows per inch, my friend’s at 8.25 stitches and 12.25 rows per inch. I was actively trying to tighten up, they were actively trying to knit loosely. Same needles. Same yarn. And still three and a half stitches per inch difference between us (and either one and quarter or two and a quarter stitches per inch difference between what we got and what the label says). The difference on the row gauge is even more dramatic.

And here’s the thing, no one has done anything wrong! Not me, not my friend, and not the yarn company. Different knitters just get wildly different gauges with the exact same yarn and needles. This is why you really do need to check your gauge, not just go by what it says on the yarn label or in a pattern. Every knitter is different, and nothing except your fabric will tell you what gauge you’re actually getting.

And I know someone is about to say ‘well I always get gauge.’ And that’s cool! You totally might usually get pretty close to the gauge printed on the yarn label. But even if you generally get the gauge listed on your yarn label, that doesn’t mean you’re going to get the gauge used in your pattern (which may be significantly different than what it says on your label). So if you’re making something where the size matters, you still need to see what’s happening with your fabric and compare that with what it says in your pattern.

Now, no one can make you do anything, and if you’re making something where the size doesn’t matter (or you don’t care what size it comes out), then do whatever you want! But if you’re just sort of trusting that using whatever needles are called for on your yarn label will get you where you need to go, you are likely to have the occasional rude surprise.