How to Hatch Chicken Eggs in an Incubator: A 21-Day Step-by-Step Guide

You've bought an incubator and you're ready to set your first eggs. But putting the eggs in and pressing the button is only the beginning. A successful hatch comes from managing temperature, humidity and turning correctly over 21 days. In this guide we walk through the whole process day by day, from preparation before setting the eggs to the chick pipping the shell.

How Long Does Incubation Take?

A chicken egg's incubation period is 21 days. The first 18 days are the "development period" and the last 3 days the "hatch period". The settings for these two periods differ; the most common mistake is forgetting to change the settings for the final 3 days.

Other poultry have different durations; this guide is for chickens, but for comparison:

Poultry	Incubation period
Chicken	21 days
Quail	17-18 days
Duck	28 days
Turkey	28 days
Goose	30-32 days

Step 1: Preparation Before Incubation

The single most important factor in your hatch rate is the quality of the eggs you set. A bad egg won't give a good result.

Choosing eggs:

• Choose clean, crack-free, normally shaped eggs. Discard very large, very small or double-yolk eggs.
• Don't wash the eggs. Washing removes the natural protective layer (cuticle) on the shell and lets microbes in. If lightly soiled, wipe with a dry cloth.

Resting the eggs:

• Before setting collected eggs, rest them pointed-end down for 12-24 hours at room temperature. This lets the air cell settle into place.
• The fresher the egg, the better. Hatch rates drop noticeably for eggs older than 7 days.

Calibrating the machine:

• Run the incubator at least 24 hours before setting the eggs. Make sure the temperature and humidity have stabilised at your target values.
• Don't blindly trust the machine's own display. Verify with a separate digital thermometer/hygrometer. On cheap machines the display and the real value can differ by 1-2 degrees, and that difference can ruin the hatch entirely.

Step 2: The Right Temperature

Temperature is the most critical incubation parameter. Even half a degree off affects the result.

• Forced-air (fan) machines: 37.5 – 37.8 °C
• Still-air (static) machines: 38.0 – 38.5 °C (measured at egg level, because in a still-air machine the top is hotter)

Most home machines are forced-air, so your target is around 37.7 °C.

Watch out for:

• Too hot and chicks hatch early and weak, with more deformities.
• Too cold and the hatch is delayed; chicks hatch late and listless.
• A short (a few hours) power cut is not a disaster. Keep the lid closed; the machine holds its heat for a while.

Step 3: The Right Humidity

Humidity is as critical as temperature but more forgiving. It splits into two periods:

• Days 1–18 (development period): 50%–55% humidity
• Days 19–21 (hatch period): 65%–70% humidity

The point of humidity is to make the water inside the egg evaporate at the right rate. During development the air cell should grow slowly; during the hatch period high humidity softens the shell and lets the chick come out without sticking to it.

How to set humidity: by filling the water trays in the machine. More water surface = more humidity. During the hatch period, fill the extra trays or add a wet sponge.

Step 4: Turning the Eggs

Eggs are turned regularly to stop the embryo sticking to the shell.

• How often: At least 3-5 times a day. An odd number is preferred (3, 5) so the egg rests on a different side each night.
• Until when: Stop turning completely at the end of day 18. After this the chick starts getting into hatch position; turning harms it.
• If your machine has an auto-turner: it does the work. Still, don't forget to switch off the turning motor on day 18.
• If you turn by hand: mark an "X" on one side and an "O" on the other with a pencil so you don't lose track of which you've turned.

Step 5: Candling (Egg Check)

Candling means holding a strong light under the egg in a dark room to see inside. It lets you track development and remove empty/dead eggs.

• Day 7: A network of veins and a small dark embryo are visible. Eggs that stay fully clear are infertile — remove them. Eggs showing a blood ring died early — remove those too.
• Day 14: Most of the egg should have darkened, with the air cell clear at the top.
• Day 18: Final check. Don't touch the eggs after this.

Removing empty and dead eggs matters: they spoil and burst inside, contaminating the other eggs.

Step 6: The Hatch Period (Last 3 Days)

From day 19 things change. This period is also called "lockdown":

1. Stop turning (at the end of day 18).
2. Raise humidity to 65-70%.
3. Don't open the lid. This is the biggest mistake. When you open the lid out of curiosity the humidity drops suddenly, the membrane shrinks onto the chick ("shrink wrap"), and the chick dies before it can hatch.
4. Once chicks start breaking the shell (pip), be patient. It can take a chick 12-24 hours to break out completely. Don't intervene; helping usually does harm.

After hatching, chicks can stay in the machine until their down dries (6-12 hours). Once dry and lively, move them to a heated brooder.

The Most Common Mistakes

• Trusting the machine's display. Always use an external thermometer/hygrometer.
• Opening the lid during the hatch period. Humidity escapes and the chick sticks to the shell.
• Forgetting to stop turning on day 18.
• Washing the eggs. It destroys the protective layer.
• Trying to track the process in your head. Which setting on which day, when turning stops, when humidity rises — these are hard to remember, and slipping up one day can risk the whole batch.

That last point is exactly why we built the Kuluçka Takip app: it automatically reminds you which day you're on, when to stop turning, when to raise humidity and the estimated hatch day. If you're running several batches you track each one separately. You can check out the app here.

If you follow the steps in this guide in order, you can get a high hatch rate on your first try. The three most critical rules: the right temperature, the right humidity, and not opening the lid during the hatch period. Get those three right and the rest largely takes care of itself.