Help with yarn/needle sizes

What’s the difference between a sport yarn and a worsted yarn?

There is a pattern I want to do from knitpicks and it doesn’t call for the sport yarn, but it comes in prettier colors. The fiber content is the exact same. I don’t know if that makes a difference.

The Sport yarn info is:
Gauge: 6 sts = 1" on #3 - 5 needles (3.25mm-3.75mm)
Amount: 110 yards/50 gram ball
And the Worsted yarn info is:
Gauge: 4.5 - 5 sts = 1" on #6 - 9 needles (4.0mm-5.5mm)
Amount: 75 yards/50 gram ball

Obviously it’s different, but would it be possible to substitute this yarn?
The pattern recommends US 11 (8mm) 32” circular needles.

Thanks Much! :knitting: :hug: :thumbsup:

Usually, doubling sport weight will get you a worsted weight. You can use the thinner yarn, but would probably have to double the number of stitches and rows, and use a 5 or 6 needle. Or you can double the thinner yarn and follow the pattern.

What’s the pattern?
It’s a shawl. Link ^

Sure you can do this easily with thinner yarn, the main part is going to be figuring how much to cast on. I think the gauge is something like 2¼ sts per inch, so the 170 st cast on comes out about 75". Figure out your gauge with the fingering yarn, which you can use size 8 to 10 needles for it, then multiply that by 75" and that will be your cast on number. You may want to put your markers 6 sts in from the edge on both ends of the row, but you can also leave them at 5 sts. That should still make a good size fringe. Then just follow the decreasing instructions to the end.