Wolf ears don't alter it. The general math for 38" hanks is to go by wig size. Monsters are roughly 5-6 and I'd rather have left over hair than not enough, also I do so much it helps me to have left overs in a consistent size. Spectra is 3 hanks to get the length to her feet and I wanted 3 colors.
This Frankie is 2 hanks cut in 3 pieces each. I planed for 2 colors and did run out of the lighter so the darker color goes more in to the back of the head then originally intended.
This is one hank cut in 6 pieces. She has a bald patch on the crown of her head because I rooted hairline in.
If you live near a Dollar Tree check their toy section for headbands with hair attached to them. It takes at least 2 to do a Monster in needle and thread so 4 if you knot. Do compare colors as they seem to have dye lots and their can be subtle but noticeable differences. And it's hit and miss which store has what. Once you cut the hair off the headband make a pony tail and trim the bottom evenly, perfectly usable hair. The new bands have 2 lengths which can be separated and used.
This is the best pic I can find at the moment but the orange and yellow are Dollar Tree headband hair needle and threaded.