Stop turning eggs on day 18 of incubation. This applies to chicken eggs, which hatch around day 21. The final three days, commonly called “lockdown,” are when the chick positions itself for hatching, and any turning at this point can interfere with that process. If you’re using an automatic turner, day 18 is when you turn it off and remove it from the incubator.
Why Day 18 Is the Cutoff
During the first 17 days of incubation, turning prevents the developing embryo from sticking to the inner shell membrane. It also helps the blood vessel network and fluid systems around the embryo develop properly. Without regular turning in those early days, embryos can develop abnormally, stick to the shell membrane, or die.
By day 18, the chick is large enough to fill most of the egg and begins orienting itself into hatching position, typically with its head tucked under its right wing and its beak pointed toward the air cell at the fat end of the egg. If you continue turning after this point, you risk disorienting the chick or shifting it into an abnormal position that makes hatching difficult or impossible.
Research on turning schedules has shown that stopping as early as day 15 doesn’t significantly reduce hatch rates. So if you accidentally stop a couple of days early, your eggs will likely still be fine. The real danger is turning too late, not stopping too soon.
What Happens During Lockdown
Lockdown refers to the period from day 18 through hatch day (typically days 18 to 21). The name is literal: you should not open the incubator during this window. Every time you open the lid, you lose humidity, and humidity is critical during these final days.
Around day 19 or 20, the chick breaks through the inner membrane into the air cell at the top of the egg. This is called internal pipping, and it’s when the chick takes its first breath of air. Shortly after, it cracks through the outer shell (external pipping) and slowly rotates inside the egg, unzipping a line around the shell until it can push free. If humidity drops after the chick pips, the exposed membranes can dry out and shrink-wrap around the chick, physically trapping it inside the shell.
Adjusting Humidity for Lockdown
When you stop turning on day 18, you also need to raise the humidity inside the incubator. During the first 17 days, most setups run at moderate humidity to allow proper moisture loss through the shell. At lockdown, the target for a forced-air incubator is around 60 to 65% relative humidity. This keeps membranes soft and pliable so the chick can rotate and push out.
If you’re using a still-air incubator (no fan), humidity is harder to measure accurately. Without air circulation, moisture layers unevenly, with more humidity near the bottom where the eggs sit and drier air near the heating element at the top. A hygrometer placed at egg level gives you the most useful reading, but expect less precision than a forced-air setup. Adding extra water channels or a damp sponge before sealing the incubator for lockdown helps compensate.
Ventilation in the Final Days
As chicks begin to pip and breathe, their oxygen demand spikes. Most incubators have adjustable air vents that should be gradually opened wider during the final days. Restricted airflow means rising carbon dioxide levels inside the incubator, which can weaken or suffocate chicks mid-hatch.
Once most eggs have hatched, you can open the vents fully and, if your incubator has viewing windows, crack those open too. At this stage, drop the temperature slightly to around 95°F. This helps newly hatched chicks dry off their down feathers without overheating. Chicks can stay in the incubator for up to 12 to 24 hours after hatching. They absorb the remaining yolk sac just before hatching, which sustains them during this period.
Lockdown Timing for Other Poultry
The day-18 rule is specific to chickens. Other species have different incubation lengths, and the general principle is to stop turning about three days before the expected hatch date.
- Ducks: Stop turning on day 25 (hatch around day 28)
- Turkeys: Stop turning on day 25 (hatch around day 28)
- Quail (Coturnix): Stop turning on day 14 or 15 (hatch around day 17 to 18)
- Geese: Stop turning on day 27 (hatch around day 30)
The same lockdown principles apply across species: raise humidity, increase ventilation, and leave the incubator closed.
Common Mistakes at Lockdown
The most frequent problem is opening the incubator to check on eggs after pipping begins. It’s tempting, especially if one chick has pipped but hasn’t made progress in several hours. But hatching is a slow process. A chick can take 12 to 24 hours from the first external pip to fully emerging, and opening the lid during that window drops humidity rapidly. Dried membranes are the leading cause of chicks that pip but never hatch.
Another common mistake is leaving the automatic turner running past day 18. Some incubators have turners on timers that don’t auto-stop, so you need to manually disable them. If you forget and the eggs keep turning into day 19 or 20, chicks may end up in the wrong position, with their heads at the narrow end of the egg or facing away from the air cell. These malpositioned chicks often can’t pip properly.
Finally, placing eggs directly on the incubator floor after removing the turner can matter. Lay them on their sides rather than keeping them upright. This gives the chick the most room to rotate during hatching.