That might depend on your own tension. I tend to crochet very tightly so I would go up, not down, but if you crochet loosely I would go the other way.Question for the crocheters with a bit more experience than me: I lost my 4mm crochet hook! It is the one that I use most often so am SUPER annoyed. Is it better to size down to 3.5mm and crochet a bit loosely, or go up to 4.5 and crochet a bit tighter than usual?