Yarn Weight Converter

Convert yarn weights between US and UK naming systems with recommended hook, needle, and gauge info.

Quick Converter

Select System

Select Weight

Full Conversion Table

US Name	UK Name	CYCA #	WPI	Needle (mm)	Hook (mm)	Knit Gauge

How to Use This Converter

Select your naming system (US or UK) and choose a yarn weight from the dropdown to see the full equivalent info.
The full table below shows all weights side-by-side for quick comparison.

US vs. UK Yarn Weight Names

The US and UK use different names for the same yarn weights. For example, what Americans call "worsted" is called "Aran" in the UK. Always check the CYCA number or WPI to confirm you have the right weight.

What is WPI?

WPI (Wraps Per Inch) is the number of times you can wrap yarn around a ruler in one inch. It's the most reliable way to determine yarn weight when labels are missing. Higher WPI = thinner yarn.