More or less yards needed?

I have done several afghans (posted several before) with a Lion Brand pattern that used their Wool-Ease Thick and Quick which is a 6-super bulky yarn. Have to make another but none of the colors suit my brother. They don’t have much variety in their colors. I have found a yarn I think would be good but it is a 5-Bulky. Will I need more yards or less going down in the weight? Using the Super bulky it took 8 skeins which was about 848 yards (with some left over). Those were 106 yards per ball. The one I am thinking about is 153 yards per ball. So my math question is, will I need more, the same, or less yardage going down to a bulky yarn?

Thanks

If you use the same number of stitches and same needle, it’ll probably take about the same amount. If you use a smaller needle and more stitches to make the same size you’ll need a little more. Or if you use a smaller needle and same stitches it could be about the same, but you’ll get a smaller blanket. You could estimate how much by comparing the gauges. If the original gets 2 sts per inch and you get 3 sts per inch, you may need half as much more.

Okay, I will fess up, I don’t do a swatch for afghans. Not that concerned about the exact size on those. The super bulky yarn was done with a size 13 and the guage is supposed to be 9sts + 12 rows = 4’", The bulky yarns says with a 10.5 size gauge is 14sts + 18 rows - 4" Guess I will need to experiment with both size needles and see what happens. I think I might have some left over yarn to try to test with different size needles and then hopefully can figure this out.

I don’t do a swatch to ‘match’ gauge, but do CO a bunch of stitches and knit several rows to see how many sts per inch I get so I know how many to cast on. I’d suggest a size 11 for the bulky unless you want a dense knit. You’ll probably get about 3 sts per inch.

If you’re really opposed to doing a swatch for an afghan, you could just start the project and measure your gauge when you get several rows done. You should be able to figure out your final dimensions based on your work-in-progress gauge, and then just buy more yarn (or not) accordingly.

Usually that’s a great idea, but for an afghan that could be over 100 sts and would take quite a bit of time to knit a few inches on it to see if it’s going to be large enough. Doing a sample with 20-30 sts won’t take nearly as much time, so you’d be able to figure it out sooner.

Thanks for the help. I will post later when I have figured it all out. I may just make an entirely different afghan this time instead of doing all the math, easier way out.