ROAS = ad-attributed revenue divided by ad spend. A 10x ROAS means 1 baht of ads brings back 10 baht. Below 1x, ad spend alone is not recovered, before any product cost. Set your own break-even ROAS from your margin: a business with tight margins needs a higher ROAS, one with low product cost can accept a lower one. If ROAS is weak, fix the creative message and the target audience before blaming the platform's algorithm. Check it weekly against actual sales.