What hook or needle size should I use?

I have listed the recommended needle or hook size below, but please check tension before embarking on a project to ensure that it fits.  (Not so important for a scarf but annoying if your hat doesn’t fit).  The hook or needle size depends on the finish required for your creation.

Yarn Weight Knitting Needle Size Crochet Hook
Lace 1.25mm – 3mm 0.75mm-3mm
4 ply 2mm – 4mm 2.5mm – 4mm
Double 3.5mm – 4.5mm 3.5mm – 4.5mm
Chunky 5.5mm -9mm 5mm – 9mm