Just took some measurements of a local sign pole to make a cozy. 19.5 cm x 200 cm. From what I understand, it is better to have it stretch a bit. It apparently stays up better that way.
My reference source: Twilight Taggers: How to Yarn Bomb
Next step, creation!
Also, Happy Autumn!
I will just tell everyone that I am making a really long scarf. 😉