"Incubator Temperature and Humidity, Dialed In"
Hatching chickens is a 21-day balancing act between two dials: temperature and humidity. Get them right and most fertile eggs hatch. Drift off, and you get early deaths, late deaths, or chicks that pip but never make it out. Here are the numbers that matter.
Temperature
The setting depends on how your incubator moves air:
- Forced-air (with a fan): 99.5°F (37.5°C).
- Still-air (no fan): 102°F (39°C), measured at the top of the eggs, because still air is warmer high in the chamber.
Stay close. A short spike does more harm than a dip, lethal territory is around 103°F in a forced-air machine and 107°F in a still-air one. If the power fails, it is safer to let eggs cool than to trap heat and risk cooking or suffocating them.
Humidity
Humidity controls how fast moisture evaporates out through the shell, which has to happen at the right pace for the chick to develop a proper air cell:
- Days 1 to 18 (incubation): about 60% relative humidity.
- Days 19 to 21 (lockdown / hatch): raise to about 70% so membranes stay soft enough for the chick to turn and break free.
Use weight loss to check yourself
Hygrometers drift, so breeders cross-check with the egg itself. Under correct humidity, an egg loses about 12 to 14% of its weight over the 21 days as the air cell grows. Weigh a sample at set and again partway through: losing too much means raise humidity; too little means lower it.
Turning
Turn eggs an odd number of times a day (so they do not rest the same way each night) through day 18, then stop at lockdown so chicks can orient and pip. Never incubate with the pointed end up.
Log it, do not guess
ChickenAncestry shows the target temperature and humidity for your batch’s current phase and lets you log readings as you take them, flagging any that fall out of range so a drifting incubator does not quietly ruin a hatch.
For the full timeline, see incubation day by day, and if a hatch disappoints, read why your eggs did not hatch. Then track your next batch free.
ChickenAncestry tracks every bird's sire and dam, draws the pedigree, and computes inbreeding (COI), free to start.
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