Knitting Needles

I am wondering if the weight/gauge of the yarn determines the size and circumference of the needles or if the size (length and width) of the project determines the size of the needles?

Thank you!

The size of the project will determine the length of the needles, but it is the weight of the yarn that will determine which size needles you need to get gauge. Different weight yarns work better with a specific needle range.

However doing a large project with a bulky yarn on large needles will get you finished quicker, but it will look different than the same pattern done on smaller needles with a lighter yarn.