Chicken eggs take 21 days to hatch. By following a few key steps such as regular turning, candling at the right times and a final lockdown, you give yourself the best chance of a strong hatch.
Chicken incubation duration and conditions
Allow 21 days at 37.5 °C (99.5 °F) in a forced-air incubator. Humidity should sit around 45-55% for the first 18 days, then rise to 65-75% during lockdown to help the chicks hatch.
Turning the eggs
From day 1 to day 18, eggs must be turned at least twice a day, ideally three times, so the embryo doesn't stick to the shell. An odd number of turns stops the egg resting on the same side every night. Automatic turners do this continuously.
When to candle the eggs
First candling is around day 7: you'll see spider-web blood vessels. A second check around day 14 confirms development. Remove clear (infertile) eggs or those showing a blood ring.
Lockdown (days 18 to 21)
On day 18, stop turning, lay the eggs on their side and raise the humidity. Avoid opening the incubator after that: the embryo positions itself to hatch and a drop in humidity can shrink-wrap it against the membrane.
Hatching
Around day 21 the chick pips the air cell internally, then breaks the shell. Give it time: hatching can take several hours. Only remove chicks once they are fluffy and dry, without opening the incubator too often.
Temperature and humidity: the right settings
The ideal temperature is 37.5 °C (99.5 °F) in a forced-air incubator, and slightly higher (38 to 38.5 °C) in a still-air model where heat is less even. Half a degree off for too long can ruin a hatch. For humidity, aim for 45 to 55% until day 18, then 65 to 75% during hatching. The best indicator is the air-cell size at candling: it should grow steadily.
Common mistakes to avoid
Opening the incubator constantly, trusting an uncalibrated thermometer, letting the water reservoirs run dry or setting eggs that are too old are the most common causes of failure. Place the incubator in a room with a stable temperature, away from direct sun and radiators, and run it for 24 hours before setting eggs to check the settings.
After hatching
Let chicks dry in the incubator for 12 to 24 hours before moving them to a brooder, kept around 32 to 35 °C for the first week. Offer lukewarm water and chick starter feed. Thanks to the yolk sac absorbed just before hatching, a chick can wait 24 to 48 hours without eating while the rest of the clutch hatches.