what size circular needles for hat
2. 16 inch needles are generally the next step up. This is the size needle you'll use for most hats. Note that the circumference of a hat is usually more like 20-22 inches. This is because any knitting project's true dimensions will be a little bit more than its dimensions while on the needles. 3. Next up are the 24 inch needles: the most common length.