How much yarn?

I would like to make the following illusion knitting pattern on a blanket.

(yes, yes, sacrilegious)

The pattern is 26 sts across, so I figure if I use bulky yarn (~3 sts per inch), and the pattern covers 1/4 of the blanket, I could make a blanket ~35"x35".

How do I decide how much yarn I will need? Is there any way to estimate how much yarn will be used per stitch? And are there any tricks when illusion knitting that would change this relationship? Once I know how much total yarn I need, how will I know how much of EACH color? Is there a website that explains all of this?

Thank you!

My best suggestion is to knit a 4x4 swatch using the pattern. Then unravel the swatch and measure how much yarn you just used. Then you can multiply it out. It’ll also give you a better idea of exactly how many stitches per inch you’ll get using illusion knitting (which I think would be different than a normal stockinette stitch)

That is a great idea, thanks! Here I am imagining some complicated system, when all I have to do is swatch.