Yarn Weight Calculator

Why a Swatch Predicts the Whole Project

Every knitter or crocheter's tension is a little different, so pattern-stated yardage is only a starting estimate for anyone whose gauge doesn't match exactly. Weighing a small swatch and scaling it up sidesteps that problem entirely — the swatch is made with your actual hands, your actual yarn, and your actual stitch pattern, so the ratio of weight to area it gives you is genuinely yours rather than an average from the pattern designer's swatch.

How to Use This Calculator

Knit or crochet a swatch of at least 4"×4" in your actual project stitch pattern, then weigh it on a kitchen scale. Enter that weight along with the swatch's width and height, then enter your finished project's width and height (for something like a blanket or shawl, where surface area is the main driver of yarn use). The default 10% buffer accounts for pattern-edge irregularities and tension drift over a larger piece.

How We Calculate It

Yarn needed = (project area ÷ swatch area) × swatch weight × (1 + buffer). For example: a 4"×4" (16 sq in) swatch weighing 10g, for a 40"×60" (2,400 sq in) blanket, with a 10% buffer → (2400 ÷ 16) × 10 × 1.10 = 1,650g.

A Few Notes

This works well for flat, roughly rectangular projects like blankets, scarves, and shawls where area is the main driver of yarn use — it's much less reliable for garments with shaping, cables, or colorwork that changes yarn consumption per square inch relative to your flat swatch. Once you know the total weight needed, check your yarn label for grams per skein to figure out how many skeins to buy, and round up rather than down given normal-batch dye-lot variation.