How much yarn do I need for seaming a sweater?

A standard pullover needs 5-8m of seaming yarn for side seams, shoulder seams, and sleeve seams. A cardigan may need 8-12m due to additional front band pickup. Always allow extra.

Should I use project yarn or separate yarn for seaming?

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.

How do I estimate seam lengths for my garment?

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.

Do I need to leave long tails for seaming?

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.

Which seaming method uses the least yarn?

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.

KnitCalcs

Seaming Yarn Calculator — Total Yarn for All Garment Seams

Calculate total yarn needed for seaming all pieces of a garment together.

Side Seam Length (each)

Underarm to hem, one side

Sleeve Seam Length (each)

Underarm to cuff, one sleeve

Shoulder Seam Length (each)

Neck edge to shoulder tip, one side

Sleeve Set-In Length (each)

Armhole circumference, one side

How We Calculate This

This calculator totals all seam lengths for a garment and applies the 3x multiplier for mattress stitch seaming.

The formula

Total seam length = (Side seams + Sleeve seams + Shoulder seams + Sleeve set-in) x 2

Total yarn = Total seam length x 3

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard yarn weights and gauge. Results may vary with individual tension, yarn brand, and needle size.