How many times do we start stitching with a needle, put it on a needle magnet, and then wonder what size it is.  Generally, I can tell a size 20 versus a size 22 especially when they are side-by-side, but not always.  And, yes, it is important to stitch with the correct size needle to help the thread through the canvas.

Here’s a great reference chart, courtesy of John James.
https://www.jjneedles.com/images/downloads/JJ-Needles-Types-and-Sizes-Guide.pdf?fbclid=IwAR0yHeyOk01ko8kjQ3WC5DJRk1lMGmin3_1eFD5S75auUCPe_qvIz-bsaXM.