Needle Size?

Hello, I am new to knitting and so far I’m loving it. I need help with something, though. I have some Bernat Satin yarn, which I love, it is so soft and silky, etc. :heart: Anyway the suggested needle size is 5.0 mm / US 8 needles. I wish to knit a scarf with two strands of yarn together. Any idea on what size needle I should use, and is there a formula for determining this?

TIA, Nancy

Doubling a worsted weight makes more like a super bulky. If you double the mm size that usually works. So 5mm doubled would be 10 mm or size 15, which should be about right.

Thank you Sue!