My MIL gave me a bunch of yarn that she got many years ago while living in Germany. I'm about to dig it out and consider it for a sweater project, but since there's no label, and I've no clue exactly how much there is, how can I determine if I've enough for a big project.

If I know that the yarn is probably a worsted, which the pattern I'm interested in calls for, and I have approximately the *weight* of the yarn called for in the pattern...would I mostly likely be good to go if I'm getting gauge? I would, of course, actually plan on having a certain percentage over, as I wouldn't want to guess right down to the ounce or anything...but is that a reasonable way to estimate how much I'll need?

Any other suggestions?

Well, never mind for that pattern...it calls for a cotton blend, and the yarn is a wool...probably too different to swap.

Still, the question will come up again when I want to do a wool pattern! Any advice is appreciated.

Yarn substitution is done all the time. Gauge is the key. If you can get the gauge the pattern calls for with your choice of yarn then you are all set. Just because the pattern might call for a different type of yarn doesn't mean you can use what you want. Gauge is the key! If you want a thinner type of yarn then you will have to make adjustments. I am making a cable hoody which called for worsted weight yarn. My son chose a thinner yarn because he liked the feel and the color of the yarn. He wanted the thickness that the pattern showed but chose a thinner yarn. I am knitting double stranded with the yarn and went up a needle size and I am right on gauge. I did knit a gauge swatch with the right size needle the pattern called for but no gauge. Up the needle size and right on gauge.
So try a swatch or two if you really want to use that yarn for that particular pattern and go from there. The other alternative is get different yarn.:guyknitting: