Knitting Yardage Estimator
Estimate how much yarn you'll need for a rectangular knit project (blanket, scarf, wrap) based on its size and your yarn's weight.
Why knitting uses less yarn than crochet for the same size
Ounce for ounce, stockinette stitch is a more yarn-efficient way to build fabric than most crochet stitches — each knit stitch pulls a single loop through, while a crochet stitch typically wraps and pulls yarn through multiple times per stitch. For the same finished dimensions in the same yarn weight, a knit project commonly uses noticeably less total yardage than an equivalent crochet one. This estimate is built around stockinette specifically; garter stitch, ribbing, and cable or textured patterns all use more yarn than plain stockinette for the same area, in some cases substantially more.
Sweater-specific factors
A garment estimate needs more than square footage: set-in sleeves and any seaming add fabric beyond the flat body measurements, colorwork (stranded or intarsia) uses more yarn than a solid color because of the floats or carried strands, and ribbed cuffs, hems, and collars are worked at a tighter gauge than the body, which uses more yarn per inch than the main stockinette section. Pattern designers usually account for all of this in their stated yardage requirements — when a specific pattern gives a yardage number, trust that over a generic estimate based on garment dimensions alone.
As with any yarn estimate, buy at least one extra skein from the same dye lot when possible, especially for a large project — most yarn shops accept an unused, unopened skein returned, and running short mid-project with no way to get an exact dye-lot match is a much worse outcome than one extra ball in the stash.