Sweater Question

I’m making a sweater, and I’ve started with the back and am working on the arm holes where the sleeves will attach later. I’ve made the curve by following the pattern. Now the pattern says to continue knitting in stockinette until the armhole measures 8 inches. Does that mean 8 inches around the arm hole or 8 inches straight up from where I started the curve for the arm hole to where the needle is?
Thanks!!

Find the row where you first did the bind off stitches or started decreasing. Follow it into your sweater and mark it; measure from that row.

Thanks, Suzeeq, but where do I continue measuring? Do I go straight up to the needle, or do I go around the curve of the arm hole?

Measure straight up.

Sorry I wasn’t clear; yes, straight up.