Thread Length Calculator

Work out how much thread a saddle stitched seam needs, in both directions, with the waste and the needle loading allowed for.

Seam length mm

One seam, measured along the stitching line.

Number of seams

Thread consumption factor

The total thread a seam consumes as a multiple of its length, covering BOTH directions. Seven to eight is the usual figure for hand sewing, being three and a half to four times the seam for each of the two passes.

Tail allowance per needle mm

Thread left hanging past each needle plus the last few stitches. A foot at each end is a practical figure.

Waste allowance %

Fraying, a cut out knot and the tail after backstitching. Ten percent for waxed thread, fifteen for a soft thread.

Thread on one spool m

Optional, for the spool count. A common spool is 25 metres.

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Free calculator by Handcraft worked examples and methodology No account, nothing stored.