For chicken eggs in a forced-air incubator, set the temperature to 99.5°F (37.5°C). This is the standard target for the first 18 days of incubation, and it applies to most common poultry species including ducks, quail, and turkeys. If you’re using a still-air incubator (one without a fan), you’ll need to run it slightly higher, around 101 to 102°F, because heat stratifies inside the cabinet and the top of the egg will be warmer than the bottom.
Forced-Air vs. Still-Air Settings
The type of incubator you own determines your target temperature. A forced-air model has a built-in fan that circulates heat evenly, so every egg sits in roughly the same environment. Set it between 99°F and 99.5°F and hold it there throughout incubation. A still-air incubator has no fan, which means warm air rises and pools near the top. To compensate, you set the thermostat 2 to 3 degrees higher so the temperature at egg level stays in the right range. Measure at the top of the eggs, not at the thermometer’s default position on the lid.
Forced-air incubators are more forgiving because temperature is uniform throughout. Still-air models require more attention and more frequent checks, especially during the first 48 hours after you load the eggs.
How Much Fluctuation Is Safe
Poultry embryos can tolerate a surprisingly wide band of temperatures for short periods. Anything between 97°F and 103°F won’t cause significant harm. The real danger zone is above that: hitting 105°F for just 30 minutes can seriously injure or kill developing embryos. On the low side, prolonged cold exposure (36 hours or longer below normal) increases embryonic mortality, delays hatch times, and produces weaker chicks that are more susceptible to dehydration.
Brief, mild swings of a degree or two are normal and expected. What matters is that the average temperature stays close to 99.5°F over the full incubation period. Resist the urge to adjust the thermostat during the first 48 hours after setting eggs. The eggs themselves are cold when they go in, so the incubator temperature will dip temporarily before recovering on its own.
Temperature During Lockdown
The last three days of incubation (days 18 through 21 for chickens) are called lockdown. During this phase you stop turning the eggs and avoid opening the incubator. Some hatch guides recommend dropping the temperature slightly during lockdown, to somewhere between 97°F and 99°F (36.1 to 37.2°C). Research on commercial hatching supports this: optimal hatchability comes from holding 37.5 to 37.8°C (99.5 to 100°F) for days 1 through 18, then reducing to 36.1 to 37.2°C (97 to 99°F) for the hatching period. The embryo generates its own metabolic heat in the final days, so a small reduction helps prevent overheating inside the shell.
Humidity also matters during lockdown. Raise it to around 65 to 70% to keep the membrane from drying out and trapping the chick. Don’t open the lid to check on progress, since each opening dumps humidity and can stall the hatch.
Settings for Ducks, Quail, and Turkeys
The good news is that most common poultry species incubate at essentially the same temperature: 99.5°F in a forced-air incubator. Ducks, quail, and turkeys all use this same setting. The differences between species come down to incubation length and humidity, not heat. Duck eggs take about 28 days (except Muscovy ducks, which take 35), quail hatch in roughly 17 to 18 days, and turkeys need about 28 days. Stop turning three days before the expected hatch date for each species.
Reptile Eggs Need Lower Temperatures
If you’re incubating reptile eggs, the temperature range is significantly lower than for poultry. Most common pet reptile species incubate between 80°F and 86°F (27 to 30°C), depending on the species. For many geckos and bearded dragons, the exact temperature you choose within that range can influence the sex of the hatchlings, a trait called temperature-dependent sex determination. Higher temperatures within the normal range tend to produce one sex, lower temperatures the other. Check species-specific guides for your particular reptile, since the correct range varies more between reptile species than it does between poultry species.
Calibrate Your Thermometer First
A thermometer that reads even one degree off can mean the difference between a strong hatch and a poor one. Before you start a new incubation cycle, check your thermometer’s accuracy with a simple ice bath test. Fill a container with crushed ice, add cold water until the ice is submerged, stir gently, and let it settle for about two minutes. Then submerge the thermometer’s sensor without letting it touch the sides or bottom of the container. After about 60 seconds the reading should stabilize at 32°F (0°C).
If it reads something different, note the gap. For example, if your thermometer shows 32.6°C in the ice bath instead of 0°C (or 33°F instead of 32°F), it’s reading about one degree high. Subtract that offset from every reading going forward. Some digital thermometers have a calibration button that lets you correct this directly. Either way, repeat the test to confirm your adjustment before trusting it with a batch of eggs.
Room Temperature and Placement
Where you put the incubator affects how stable it runs. A room that swings between 60°F during the night and 85°F during the day forces the thermostat to constantly compensate, which increases the chance of overshooting or undershooting. Aim for a room that stays in the mid-70s if possible. Keep the incubator away from windows, exterior walls, heating vents, and direct sunlight. A consistent ambient temperature means your incubator’s heater cycles on and off less frequently, which produces a smoother, more stable internal environment for developing embryos.