I usually buy 2 pounds of yeast at a time. there's 2 1/2 cups of yeast in a pound. It last a long ass time.
If a person was running short, the no knead artisan bread only uses a quarter teaspoon. I don't care for it much though. It's got a hard crust and a weird crumb. I love the taste though, the long fermentation makes it taste great.
