Seaming Yarn Calculator — Total Yarn for All Garment Seams

At this calculator's default 3x multiplier (mattress stitch), a standard pullover needs roughly 8-12m of seaming yarn for its side, shoulder and sleeve seams. A cardigan may need 12-18m due to additional front-band seaming. If you instead follow the leaner 1.5x rule of thumb (Ysolda/Purl Soho: 1.5x seam length plus a ~30cm weaving-in tail), the same pullover needs about 5-6m. Always allow extra.

Using the same yarn as the project creates an invisible seam. If the project yarn is textured, slippery, or very thick, you may prefer a smooth, matching-colour yarn in a similar weight for easier sewing.

Measure your finished pieces: body side seams from underarm to hem, sleeve seams from underarm to cuff, shoulder width, and armhole circumference for set-in sleeve attachment.

When binding off, leave a tail 3x the seam length. For example, a 40cm side seam needs a 120cm tail. This avoids having to join new yarn mid-seam. If tails are too short, add new yarn with an overlapping join.

Backstitch uses the most yarn (~4x seam length). Mattress stitch uses ~3x. Whip stitch uses ~2.5x. Kitchener stitch (grafting) uses ~3x. Crochet slip stitch join uses ~2.5x. Choose based on the desired finish, not just yarn usage.