How many yards of yarn to make a king size crochet blanket?

To crochet a Queen-sized blanket, it all depends on what type of yarn you use, the pattern you are using, the hook size, and your gauge.

The top area of a Queen-sized bed is 60in x 80in--then there would be overhang to hang over the edge of the bed. So a fairly standard size of a quilt would be 102in x 112in.

Looking around, I found some amounts of yarn--but these are really, really just estimates! Check your pattern for specific yarn, hook, gauge requirements.

I would guesstimate that you would need at least 6000yards, of yarn; or 32 balls of 3.5oz skeins; or 8lbs--14 skeins, of yarn.