For a 16 oz. takeout cup:
With worsted weight yarn and a G hook, chain 30. Join into a ring and hdc into each chain. Increase 2 sts every other round (e.g. inc 1, hdc 12, inc 1, hdc rem), checking the fit every once in a while, working a plain round to tighten it up if necessary. I like a cozy about 6 rounds high. Stretchy yarns like wool need fewer increase rounds – increasing 2 sts every third round might do the trick. If you want it to fit lower, start with a shorter foundation chain.
Found info on where to find the pattern here: