What do thread weight numbers mean?

Thread weight is measured in wt (weight): 40wt is standard embroidery, 30wt is heavier, 60wt is finer. Higher numbers mean thinner thread. Weight affects coverage, stitch density, and the look of the finished design.

How do I convert between metres and yards?

1 metre = 1.094 yards. 1 yard = 0.914 metres. Many US patterns and thread brands use yards; UK and European brands use metres. This calculator converts between them automatically.

What spool sizes are available?

Mini spools: 200-500m. Standard spools: 1,000m. King spools: 5,000m. Cones: 5,000-10,000m. For occasional use, standard spools are fine. For production work, king spools or cones are more economical.

Does thread weight affect the spool length?

Yes. Heavier threads (30wt, 12wt) take up more space on the spool, so the spool contains fewer metres. A 1,000m spool of 40wt equals roughly 800m of 30wt or 500m of 12wt by length.

SewCalcs

Thread Conversion Calculator — Weight & Length

Convert between thread length units and estimate spool needs.

Thread Length

Unit

Spool Size

How We Calculate This

Thread length is converted between metric and imperial units. Spool estimates are based on the selected spool size.

The conversions

1 metre = 1.094 yards = 3.281 feet

1 yard = 0.914 metres = 3 feet

Spools = ceil(Total length ÷ Spool size)

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before cutting or purchasing fabric.