Over several years, I have struggled with the question. How many chickens do I need? It has taken several years to figure out an answer because there are a lot of variables.
First, how many eggs do you want per day? Do you plan to sell or give away eggs? I think you will find that the more eggs you have the more eggs you will use. Our average egg consumption is about 12 eggs per day for our two families, 
Secondly, what type of birds do you want? Do your research because each breed has different qualities. For our first year, I purchased 24 Buff Orpingtons. All was well until they all went broody almost all at the same time and egg production went to 2-3 eggs per day, but we sure got lots of baby chicks. For example, Orpingtons and Australorps will lay an egg just about every other day. Leghorns will lay an egg every day and Rhode Island Reds will lay about 5-6 eggs per week.
Lastly, the age of your birds is an important factor. I keep a young flock, replacing them every 18-24 months. Once a hen is 24 months old her egg production will slowly decline. So, the older your hens are the more hens you will need to maintain the desired egg production.
Back to my original question: How many chickens do I need? If I have 20 Rhode Island Reds and 8 Buff Orpingtons I will get a yearly average of 14-18 eggs every day. Certain times of the year we will have more which allows me to give away extra eggs. I seldom sell eggs because people in our area do not want to pay more than $2.00/dozen.
I have found that a good rule of thumb is that you need twice the number of chickens as what you need for eggs each day.
The only two breeds I need.
https://steemit.com/homesteading/@hansjurgen/6iqkho-the-only-two-chicken-breeds-i-need
Cheers and thanks for your up-vote, Tim and Joann