Kromski WPI Gauge

Measuring yarn weight — simply and reliably

Anyone who processes handspun yarn into knitting or weaving projects needs to know its yarn weight. Not for aesthetic reasons — but because stitch count, needle size, and thread spacing all depend on it. The established measurement method in hand spinning is called WPI: Wraps Per Inch. You wrap the yarn tightly around a ruler or tool, count the wraps across one inch, and can thereby determine the yarn weight category (lace, fingering, DK, bulky, etc.).

The Kromski WPI Gauge is a small wooden tool made exactly for this purpose. It has a milled groove of the correct width (1 inch = 2.54 cm) that you wrap the yarn around and read off. No ruler, no guessing, no holding with both hands — the gauge sits stably in the hand and gives a reproducible result.

What WPI is used for

• Classifying handspun yarn before knitting it
• Checking whether a yarn matches a knitting pattern (WPI categories are internationally consistent)
• Calculating the correct sett (threads per inch) when weaving
• Comparing two yarn batches without needing scales

Frequently asked questions about the WPI Gauge

What do the WPI categories mean?

As a rough guide: 30+ WPI = laceweight, 20–26 WPI = fingering/sock weight, 14–18 WPI = sport to DK, 10–14 WPI = worsted, 6–9 WPI = bulky, below 6 = super bulky/art yarn. These ranges vary slightly by source — the gauge delivers the measurement; the classification depends on the project.

Do I have to measure in inches or can I use centimetres?

WPI is an anglophone convention (Wraps Per Inch), but the standard is used worldwide — knitting patterns, weaving setts, and yarn manufacturers all use it. The gauge is designed for 1 inch (2.54 cm). To convert to WPC (Wraps Per Centimetre): WPC = WPI ÷ 2.54.

Can I use the gauge for weaving yarn too?

Yes — in weaving, WPI is often used to estimate the sett (warp threads per inch). A rough rule: the sett for plain weave is approximately WPI ÷ 2. The gauge gives the basis; the sett depends on the weaving style and fibre type.