Not So Rigid Weaver

Musings on weaving on a Rigid Heddle Loom and beyond

Ashenhurst Sett Calculator

This sett calculator is useful when you know the weight and length of yarn, and particularly for finer yarns. The maximum sett here should be about wraps per inch * 0.7.

The range between 50% and maximum typically gives a wider range than other sett charts; most weaving will be closer to the 70-80% values for general balanced plain weave or twill. The value for woolen is for items that are intended to shrink.

Numbers are rounded to 1 decimal point because that's how precise some rigid heddles are and to help you make decisions when it falls between a fixed sett.

Ashenhurst Sett Calculator

Length of yarn per given weight. Default of 1680 is 8/4 cotton's yards per pound.
The weight of yarn of the given length.
The type of fibre has a small impact on the diameter. If unsure, leave as default.
  • Yards Per Pound:
  • Ashenhurst Diameters per inch:
DescriptionEnds Per Inch (EPI)
Plain WeaveTwill
90% of Max (Upholstery)
80% of Max (Production)
70% of Max (Clothing)
65% of Max (Woolen)
60% of Max (Clothing)
50% of Max (Delicate)
Calculator by NotSoRigidWeaver based on Ashenhurst's formula via Peggy Osterkamp

Check out Not So Rigid Designer, my online weaving software for rigid heddle loom weavers!

Thomas R. Ashenhurst wrote a number of books on textiles in the late 19th & early 20th century, including A treatise on textile calculations and the structure of fabrics, but I haven't been able to find a reference to this specific formula. I plan to get my hands on Peggy Osterkamp's book soon to see if there's a more specific reference!

My impression is that for thicker yarns, like a worsted cotton, this formula may suggest too dense of a sett - it was developed which much finer yarns in mind.

For an embeddable widget version of this calculator, use