To incubate chicken eggs successfully, stabilize the incubator before setting fertile eggs, maintain the correct temperature and humidity, turn the eggs through day 17, and begin “lockdown” on day 18. Most chicken eggs hatch around day 21. Small, consistent adjustments are safer than repeatedly opening the incubator or making large setting changes.
This guide covers the complete 21-day process for a small forced-air or still-air incubator. Always compare these ranges with the instructions for your exact model because sensor location, fan design, room humidity, elevation, and egg size can affect operation.
Chicken Egg Incubation Settings at a Glance
| Stage | Temperature | Relative humidity | Turning | Main job |
|---|---|---|---|---|
| Before setting | Stabilize for at least 24 hours | Confirm both sensors | Test the turner | Clean, calibrate, and observe |
| Days 1–17 | About 99.5–100°F in a forced-air incubator; follow model guidance for still air | Commonly about 50–60% | Automatic, or at least 3 times daily | Keep conditions steady and candle briefly |
| Days 18–21 | Continue the model’s recommended hatching temperature | Commonly about 65–70% | Stop turning | Lock down, increase ventilation, and avoid opening |
| After hatch | Move dry chicks to a preheated brooder | Not applicable | Not applicable | Provide brooder heat, water, and chick starter |
What You Need Before You Start
- A clean incubator sized for your planned hatch
- An accurate thermometer positioned as the manufacturer directs
- A calibrated hygrometer or the model’s reliable humidity display
- An automatic egg turner, or a pencil and turning record for manual turning
- A purpose-built egg candler or a bright, cool LED light
- Clean water and a safe way to add it without wetting the eggs
- Fertile hatching eggs from a healthy flock or reputable source
- A fully prepared brooder, feeder, waterer, bedding, and chick starter feed
Plan the chick setup before the eggs are due. Our complete brooder setup guide explains the equipment, while the baby chick care guide covers heat, water, feed, bedding, and daily checks after hatch.
Choose and Store Fertile Hatching Eggs
Only fertile eggs can develop. If the eggs came from your own flock, a rooster must have had access to the hens. Fertility still is not guaranteed, so candle later instead of assuming every egg will grow.
Select normal-sized, intact eggs with reasonably clean shells. Do not set cracked, leaking, badly misshapen, unusually thin-shelled, or heavily soiled eggs. Avoid washing hatching eggs; scrubbing and soaking can damage the shell’s protective bloom and may draw contamination through the pores. A slightly dusty egg is usually a better candidate than one that requires aggressive cleaning.
For best results, set eggs within seven days of laying. If they must wait, store them large end up in a cool location around 55–60°F, not in a household refrigerator. Tilt or turn stored eggs gently once or twice daily. Before setting, allow cool eggs to warm gradually toward room temperature so condensation does not form on the shells.
If you are deciding between shipped eggs, local hatching eggs, and already-hatched chicks, review our guide to buying baby chicks and hatchery options.
Prepare and Test the Incubator
Clean and dry the incubator, racks, water channels, and turner according to the manufacturer’s instructions. Place the unit indoors on a level, stable surface away from direct sun, exterior doors, heating vents, drafts, and heavy traffic. A room with a steady temperature makes the incubator’s job easier.
Install the thermometer and hygrometer exactly where the model requires. A reading near the lid can differ from conditions at egg height, especially in a still-air incubator. Check the built-in readings against separate, known-accurate instruments and test the automatic turner before adding eggs.
Run the incubator empty for at least 24 hours; longer is useful if the room temperature changes between day and night. Confirm that temperature and humidity recover normally after adding water. Do not place valuable eggs into a machine that is still drifting or whose alarms and turner have not been tested.
Temperature: Forced-Air vs. Still-Air Incubators
A forced-air incubator uses a fan to distribute heat and commonly operates around 99.5–100°F. A still-air incubator develops temperature layers and often requires a slightly higher reading at the top of the eggs; Illinois Extension lists about 100.5°F for chicken eggs in its still-air model guidance. Follow the instructions and sensor position for your particular unit rather than transferring a forced-air setting to a still-air machine.
Brief, small fluctuations are less dangerous than prolonged overheating. Do not chase every momentary change by turning the control repeatedly. Let the unit settle, verify the reading with the second thermometer, and make one small adjustment at a time. Consistently early hatches can indicate that average temperature ran high; consistently late hatches can indicate that it ran low.
Humidity and the Egg’s Air Cell
Humidity controls how quickly moisture leaves the egg and how the air cell grows. Extension references vary somewhat: common recommendations for the first 18 days fall around 50–60% relative humidity, followed by roughly 65–70% for hatching. Use your incubator instructions as the starting point, then check air-cell growth or egg-weight loss across the hatch rather than relying on one number alone.
If the air cell remains too small, the eggs may be losing too little moisture and humidity may be too high. If it becomes too large too quickly, humidity may be too low. Climate matters: the same water-trough setup can behave differently in an arid home and a humid one. Add warm water through the designated port when possible and keep water off the eggs.
How and When to Turn Chicken Eggs
Turning keeps the developing embryo from remaining against one side of the shell membranes. An automatic turner provides the most consistent schedule. For manual turning, mark opposite sides with a pencil—such as X and O—and turn the eggs gently at least three times per day. An odd number of turns prevents them from resting on the same side every night.
Eggs in an upright turner generally sit large end up. Eggs turned by hand can lie on their sides and be rolled gently. Wash and dry your hands before handling them, avoid jolts, and keep the incubator open only as long as necessary. Stop all turning at the beginning of day 18.
Candling Chicken Eggs on Days 7 and 14
Candling shines a cool light through the shell so you can check development without opening the egg. Work in a dark room, handle one small group at a time, and return eggs promptly. Dark or heavily pigmented shells may reveal less detail, so do not discard an uncertain egg too early.
What to look for when candling
- Around day 7: a living embryo often appears as a dark spot with branching blood vessels. A clear egg may be infertile, but wait and recheck if the shell is difficult to see through or the incubation clock is uncertain.
- Around day 14: the embryo occupies more of the egg, movement may be visible, and the air cell should be noticeably larger.
- Blood ring or stopped development: a ring with no normal vein network can indicate early embryo loss. Compare with reliable candling references before removing an egg.
- Leaking, cracked, or foul-smelling egg: remove it carefully. A spoiled egg can contaminate the incubator or burst.
Illinois Extension notes that candling is useful from roughly day 5 through day 17. Avoid routine candling after lockdown begins. For additional examples, see the university’s egg candling guidance.
The 21-Day Chicken Egg Incubation Timeline
Days 1–6: Establish consistency
Confirm temperature, humidity, ventilation, and turner operation at least morning and evening. Record the readings instead of relying on memory. Avoid unnecessary opening during these sensitive early days.
Day 7: First candle
Candle briefly for a vein network and embryo shadow. Recheck questionable eggs later rather than making a rushed decision.
Days 8–13: Monitor and turn
Continue the stable routine. Refill water as needed without flooding the incubator, and verify that an automatic turner has actually changed position.
Day 14: Second candle
Check that the embryo has grown and that the air cell is progressing. Remove only eggs you are confident have stopped or are unsafe.
Days 15–17: Prepare for lockdown
Finish the brooder, chick feed, and safe water setup. Plan how you will raise the humidity without opening the lid repeatedly. If using a removable turner, review the model’s instructions before day 18.
Day 18: Begin lockdown
Stop turning, remove the turner if required, place eggs in their hatching position, raise humidity to the model’s hatching range, and provide the recommended ventilation. Do not candle routinely after this point. The chick begins positioning itself for hatch.
Days 19–20: Internal and external pipping
A chick may first break into the air cell, begin breathing, and peep inside the egg. It then makes an external pip through the shell. Long quiet rests between stages are normal while the chick absorbs the remaining yolk and prepares to hatch.
Day 21: Hatch day
The chick works around the shell in a process called zipping, then pushes free. Resist the urge to peel the shell away. Premature assistance can tear active blood vessels or interrupt yolk absorption. A hatch can extend into day 22 or later, especially if average temperature ran slightly low.
Lockdown: Why You Should Keep the Incubator Closed
Opening the incubator during pipping releases warm, humid air. Humidity can recover slowly, and exposed membranes may dry around a chick. Keep the lid closed unless there is a genuine safety problem. Use viewing windows, external water ports, and the incubator display instead.
Do not close ventilation holes simply to hold humidity. Developing embryos need oxygen, and carbon dioxide must escape. Mississippi State University Extension identifies temperature, humidity, ventilation, and turning as the main environmental controls for a successful hatch.
When to Move Chicks to the Brooder
Leave newly hatched chicks in the incubator until they are dry, fluffy, and able to stand—often several hours and sometimes up to about 24 hours. Avoid opening the lid repeatedly for each chick while others are pipping.
Move them together to a brooder that is already warm and stable. Show each chick the water, provide fresh chick starter, and give them room to move away from the heat source. The chicken feeding guide explains age-appropriate feed, grit, and treats. As they grow, the hen-or-rooster guide can help you understand when sex-related clues become more reliable.
Incubation Troubleshooting
| Problem | Possible contributors | What to review before the next hatch |
|---|---|---|
| Many clear eggs | Infertility, eggs stored too long, poor storage, or development too early to see | Breeder fertility, egg age, storage temperature, and candling timing |
| Embryos stop early | Temperature problems, contamination, rough handling, breeder nutrition, or genetic factors | Calibration, sanitation, egg quality, and handling records |
| Hatch is consistently early | Average incubation temperature may be high | Thermometer accuracy and sensor location |
| Hatch is consistently late | Average incubation temperature may be low | Room stability, calibration, and recovery after opening |
| Chick pips but does not finish | Humidity, temperature, ventilation, positioning, or developmental problems | Air-cell growth, lockdown settings, vent position, and turning history |
| Wet or swollen chicks | Humidity may have been too high; temperature or infection can also contribute | Humidity records, sanitation, and incubator accuracy |
| Membranes appear dry | Low hatch humidity or frequent opening during lockdown | Hygrometer calibration, water surface area, and lid-opening history |
One unsuccessful egg does not prove that a setting was wrong. Look for patterns across the entire hatch and keep records. If repeated hatches fail despite verified equipment, ask an experienced breeder, poultry veterinarian, or your local Extension office to review fertility, breeder health, sanitation, storage, and incubation practices.
Frequently Asked Questions
How long do chicken eggs take to hatch?
Chicken eggs usually hatch about 21 days after incubation begins. Some hatch on day 20, 22, or later. Consistently early or late hatches are a reason to verify average temperature and thermometer accuracy.
What temperature should a chicken egg incubator be?
A forced-air incubator commonly runs around 99.5–100°F. Still-air models may require a different temperature and sensor position, often measured near the top of the eggs. Follow the manual for the exact incubator and confirm it with a second accurate thermometer.
How often should chicken eggs be turned?
Use a reliable automatic turner or turn manually at least three times each day through day 17. Stop turning at the beginning of day 18.
When should I candle chicken eggs?
Days 7 and 14 are practical checkpoints. Candle briefly in a dark room and avoid routine candling after lockdown starts on day 18.
Should I help a chick hatch?
Usually, no. Resting after a pip can be normal, and helping too soon can cause severe bleeding or interfere with yolk absorption. If a chick is clearly in distress, seek real-time advice from an experienced poultry professional who can assess the hatch stage and membrane condition.
What should I do with eggs that have not hatched?
Allow extra time for late hatches if temperature may have run low. Illinois Extension suggests leaving unhatched chicken eggs until about day 23 or 24. After that, remove them carefully and dispose of them without opening questionable or foul-smelling eggs indoors.
Sources and Further Reading
- Mississippi State University Extension: Hatching Quality Chicks
- University of Illinois Extension: Incubation and Embryology Q&A
- University of Illinois Extension: Candling Eggs
- Penn State Extension: Hatching
A successful hatch begins with healthy breeder birds and ends with a prepared brooder. For the next stage, continue with How to Care for Baby Chicks and review common baby chick health issues before the chicks arrive.
