Sweater Sizing Calculator

This calculator sizes the major pieces of a basic drop-shoulder sweater body from a chest measurement, desired length, and gauge. It first adds a fixed 2 inches of positive ease to your chest circumference — sweaters are traditionally sized with some room rather than negative ease, unlike the hats and socks in this same tool family — then converts that eased circumference to a full-body cast-on count using your stitch gauge. That cast-on is split roughly in half between front and back pieces (with any odd stitch going to the back, since back stitches is calculated as the remainder after subtracting front from the total), and sleeve stitches are estimated separately as 35% of the eased chest circumference, a rough proxy for typical upper-arm width relative to chest size.

Body rows come from your desired body length times row gauge, rounded up so the piece is never shorter than intended. The yarn estimate is a coarse approximation — total cast-on stitches times body rows times a flat 0.5-inch-per-stitch yarn consumption figure, converted from inches to yards — and should be treated as a ballpark, not a shopping list; actual yarn use varies substantially by stitch pattern, yarn weight, and whether cables, ribbing, or colorwork are involved. This calculator also doesn't account for waist shaping, raglan or set-in sleeve caps, or neckline shaping, all of which change the true stitch counts of a finished garment — it's a starting point for a straight-sided body, not a full pattern.