There will be skeins that do not tell you the yardage. I usually measure the yardage with a yard counter that is specific to yarn. Unfortunately, my son broke it. I am currently in the works to having it fixed and looking for a replacement that has equal to higher accuracy rates. Tempted as I may be to using a niddy noddy, it is known that they are not the most accurate tools for yarn measurement. I will add a guesstimate online. However, if a tag has an actual measurement, it is probably because it was spun prior to this conundrum. Thanks for understanding. I will be sure to update again once my yard counter is fixed/replaced.