Artificial incubation

Chicken egg incubation can successfully occur artificially as well. Nearly all chicken eggs will hatch after 21 days of good conditions - 99.5 °F (37.5°C) and around 55% relative humidity (increase to 70% in the last three days of incubation to help soften egg shell). Many commercial incubators are industrial-sized with shelves holding tens of thousands of eggs at a time, with rotation of the eggs a fully automated process.

Home incubators are usually small boxes (styrofoam incubators are popular) and hold a few to 50 eggs. Eggs must be turned three to five times each day, rotating at least 90 degrees. If eggs aren't turned, the embryo inside will stick to the shell and likely will be hatched with physical defects. This process is natural; hens will stand up three to five times a day and shift the eggs around with their beak.