Fiber-to-Yarn Yield Calculator

Before you buy fiber for a project, it helps to know how much finished yarn it will actually produce — and that number depends on both how much fiber survives processing and how thick you plan to spin it. This calculator applies two sequential loss stages to your raw fiber weight: first a wash yield percentage (raw fleece typically retains only 50-70% of its weight after scouring out grease, dirt, and vegetable matter, while pre-washed roving or top retains 90-98%), then an additional prep-loss percentage for waste from carding, combing, or picking. What remains is the spinnable fiber weight.

Separately, it estimates yardage per pound of the finished yarn from your target WPI using McMorran's balance — a widely-used handspinning approximation where yards per pound equals your WPI value squared, scaled up by a factor of 100, then split across however many plies you're spinning — and multiplies that per-ounce yardage by your spinnable fiber weight to get the total estimated yards you should be able to spin. The overall yield percentage (spinnable weight over raw weight) is a single number useful for comparing whether a cheaper, dirtier fleece is actually a better value than a more expensive, cleaner one once processing loss is priced in. Because both the wash yield and McMorran's balance are estimates rather than measurements, treat the total yardage as a planning figure — your actual results will vary with how tightly you spin, how consistent your WPI is across the skein, and how thorough your washing and prep actually are.