The leaves on the larger crochet leaf bookmarks are about 2 inches/5 cm long. You can make the chain part as long as you’d like your bookmark to be. The green one is about 12 inches/30.5 cm not counting the leaf, while the blue one is about 7 inches/17.78 cm excluding the leaf.

The embroidery floss one’s leaf is not quite an inch/2.5 cm, and the chain is about 8.5 inches/21.59 cm.

You can change up how you make the leaf to make it smaller or bigger, use thicker or thinner yarn (and corresponding size hook) and make the chain part however long you want. You can also single crochet down both sides of that chain to make the bookmark part wider, or use bigger stitches if you like.