How many lbs of shredded chicken will serve 20 people?

It depends on how much shredded chicken you want to serve each person!

Here's a general guideline:

* Light snack or side: 2-3 ounces per person, so 40-60 ounces (2.5-3.75 lbs) total

* Main course: 4-6 ounces per person, so 80-120 ounces (5-7.5 lbs) total

* Heavier main course (like tacos): 6-8 ounces per person, so 120-160 ounces (7.5-10 lbs) total

Always better to have too much than too little! It's better to err on the side of having a little extra, especially if you're serving a crowd.