Short answer: A chicken egg takes 21 days to hatch, and each day has a job: days 1 to 3 the heart and blood vessels form, days 7 and 14 are your candling checks, day 18 is lockdown when you stop turning and raise humidity, and days 19 to 21 are hatch. Write the day on the machine's log every morning so you can see when something drifts, not just that it did.
Key takeaways
- Count day 1 as the day you set the eggs, and write that date on the machine before the first egg goes in.
- Candle on day 7 and again on day 14, and remove clear eggs and dead embryos only after you have looked at them properly.
- Lockdown on day 18 means no more turning, a humidity rise, and no opening the lid for anything except an emergency.
- Most chicks start pipping on day 19 or 20 and hatch on day 21. A chick still in its shell on day 22 is not automatically dead.
- Keep a daily log of temperature, humidity and turning. The log tells you what changed; memory does not.
Why the day count matters more than the machine
A farmer rang us last March to say his eggs had gone soft and smelled wrong on day 12. He had kept his machine at the right temperature. What he had not done was write anything down, so when he asked us what went wrong, he could not tell us whether the trouble started on day 2 or day 10.
Every stage of the 21 days depends on the one before it. If you know which day you are on, you know what the embryo should be doing and what you should be checking. Without a day count, every problem looks the same.
So before anything else, write the set date on a card and stick it to the front of the machine. Then start each morning by crossing off the day.
Days 1 to 7: the heart starts and the blood vessels spread
In the first 24 hours the embryo is a small pale disc on the yolk. By day 2 the heart is beating and the blood vessels are running across the yolk sac. By day 4 the main body shape is visible. By day 7 the eggs should show a clear network of veins when you hold a light to them.
This is why the first week is the most sensitive. Heat that drifts above about 39 °C for an hour or two can kill embryos that are still forming. The chick is not weak in this stage, it is fragile, and the damage does not show until candling.
Your job in this week is simple and mostly boring:
- Check the thermometer at tray level, not on the lid. Trays at the back of a machine often run cooler.
- Turn the eggs at least three times a day, or let an automatic turner do it, and make sure it actually moves.
- Do not open the lid more than you have to. Each time you open it, the temperature drops and the humidity escapes.
Day 7: the first candling and what to pull out
Candling means holding a strong light against the shell in a dark room and looking at what is inside. On day 7 you are looking for three things: a clear network of veins, a dark embryo spot with a visible shape, and an air cell that is starting to form at the blunt end.
Eggs that look clear, with no veins and no dark spot, are infertile or died very early. Take them out. Eggs with a ring of blood around the inside of the shell, or a dark spot that has collapsed and is spreading, are dead. Take those out too, and make a note of how many.
Do not panic if you remove a few. A normal set from a good flock will lose a small share of eggs by day 7, and the number depends a great deal on the breeding stock and how the eggs were stored before they were set.
| What you see on day 7 | What it usually means | What to do |
|---|---|---|
| Clear egg, no veins | Not fertile, or died very early | Remove and record |
| Veins and a dark spot that moves when tilted | Developing normally | Leave in place |
| Blood ring around the inside of the shell | Embryo died in the first week | Remove and record |
| Veins but no dark spot | Embryo stopped early | Remove and record |
Days 8 to 13: the quiet stretch where mistakes hide
Between day 8 and day 13 the embryo grows fast and nothing much looks different from outside. Farmers relax here, and this is where the most avoidable losses happen. The usual cause is humidity that has slipped too low because the water tray was not topped up after the first candling.
Dry air in this stage causes the membranes to tighten and the air cell to grow too large. You will not see the problem until day 18, when the chick has no room to position itself. The fix is to check the water level every morning and keep the humidity inside the range in our temperature and humidity chart for setting.
Two checks in this stage pay back the effort:
- Weigh a few marked eggs on day 7 and again on day 14. You want them losing weight steadily, not in a sudden drop.
- Make sure the turning has not stopped quietly. An automatic turner that has jammed looks fine from the front door of the room.
Day 14: the second candle and the weight check
On day 14 you candle again. The embryo should now fill most of the egg, and the veins at the edge of the yolk should be darker and more crowded. The dark outline of the embryo should be easy to see, and the egg should look heavier and more solid than on day 7.
This is the last point where you can take a clean decision about a clear or dead egg without disturbing the hatch. If an egg is still clear on day 14, it is not coming back. If the embryo has stopped and the egg looks dark and empty, remove it before it contaminates the others.
We give a farmer one piece of advice at this stage. Do not judge the whole batch from the eggs on top of the tray. Candle the eggs from the back and middle too. Machines with uneven heat often lose a whole row, and you only find it if you look.
Day 18: lockdown, stopping the turner and raising humidity
Day 18 is lockdown. From this point the egg stops being turned. The chick has to settle with its head toward the air cell, its beak under the right wing, and turning now would tangle the membranes and kill it.
Three things change on day 18, and all of them should happen in the same visit:
- Stop the turner, or lay the eggs flat and leave them, and mark the tray so no one turns it by mistake.
- Move the eggs to the hatcher, or raise the humidity to the hatch level in the same machine. Hatch humidity is usually higher than setting humidity, and for most chicken eggs it sits in the upper 60s percent.
- Lower the temperature slightly, as your machine's guide says. Chicks give off heat once they start moving, and a hatcher that stays at setting temperature can overheat them in the last hours.
Do not open the machine to look at the eggs on day 18. You have already done your checks. Each opening drops the humidity you have just built up.
Days 19 to 21: pipping, zipping and the hatch
On day 19 or 20 you should start to hear chicks. The first sign is a small hole in the shell, called pipping. The chick breaks through with its beak and then works its head round the shell, which is called zipping. Once the shell is open, the chick rests for several hours before it stands.
Expect the hatch to run across about 24 hours. A chick that pips on day 20 may not come out until the morning of day 21. Chicks that have pipped but not zipped within 12 hours may be stuck (our guide to failed hatches explains the usual causes), and we cover what to do about that in our assisted hatching guide.
Leave the lid closed while chicks are coming out. Wait until the chicks are dry and fluffed before you move them. In our hatchery the rule is simple: the machine is not finished until the last chick has been dry for 12 hours, and nothing is moved before that.
Ghana conditions that change the daily routine
The 21-day schedule is fixed, but the humidity you need to hit it is not. In Ghana the air changes sharply over the year, and it changes inside a room in the same day.
During the harmattan, from about December to February, the air is dry and dusty. Setting humidity often falls below target in a room without air conditioning, and the water tray empties quickly. Top it up twice a day in this season, and keep a small hygrometer in the room as well as the one on the machine.
In the rainy months, roughly April to July and again in September and October, the air is damp. The machine may read high on humidity while the eggs are actually dry, because the room air is saturated. Check the air cell at candling and the weight on day 14, not the number on the screen alone.
Power is the third problem. A cut during days 1 to 17 is a worry. A cut on day 19 can be fatal if the machine stays cold. Plan your backup before you set, and read our guide to incubating through power cuts.
Need chicks for your next batch?
Send breed, number and town. We reply with price, hatch date and delivery cost in writing.
The daily log: what to write down and why
A log takes two minutes a day. It is the only way to know whether a bad result came from the eggs, the machine or your routine. The batch record we send with our chicks is built on the same idea.
Each morning, write down:
- The day number and the date.
- Temperature and humidity at tray level, and whether either was outside range overnight.
- Water level, and how much you added.
- Whether the turner ran, or whether you turned by hand and how many times.
- Any eggs removed, with the day and a short note on what they looked like.
After the hatch, add the number of chicks out, the number of pipped but dead, and the number of unhatched eggs. Those three numbers, read against your daily log, show you where the loss happened.
A worked example from one set of 120 eggs
Take a farmer in Kasoa who sets 120 Ross 308 eggs in a forced-air machine in late November. Here is how a normal set might look, using rounded numbers you can compare with your own.
| Stage | Eggs left | Note |
|---|---|---|
| Set, day 1 | 120 | Machine stable at setting temperature for 24 hours before loading |
| Candle, day 7 | 112 | Eight clear or early-dead eggs removed |
| Candle, day 14 | 106 | Six more removed, one tray found 1 °C cool |
| Lockdown, day 18 | 104 | Two eggs with air cell too large, dry week in harmattan |
| Hatch, day 21 | 91 | Thirteen unhatched, most dead at day 19 to 20 |
A 76 percent hatch from set may look poor, but the farmer found the cause. The cool tray was corrected on day 14, and the dry week was seen in the log. Next set, with the water level checked twice a day in harmattan, the figure went up. The point is not the number, it is that the log made the cause visible.
Common mistakes at each stage
- Days 1 to 7: loading eggs into a machine that has not reached stable temperature. Run it empty for at least 24 hours first.
- Days 8 to 13: forgetting the water tray after the first candle. Put a reminder on the wall.
- Day 14: throwing out a clear-looking egg that still has a faint vein network. Use a bright light and look again.
- Day 18: turning eggs once more because they look restless. They are not restless, they are settling.
- Days 19 to 21: opening the lid to help a chick that is still zipping. Most chicks that are struggling need time, not hands.
A checklist you can print and stick to the machine
- Set date written on the card and on the log.
- Machine run empty and stable for at least 24 hours before loading.
- Water tray filled and checked every morning, twice a day in harmattan.
- Turning at least three times daily, or automatic turner confirmed working.
- Candle on day 7 and day 14. Remove clear and dead eggs and record them.
- Lockdown on day 18: turning stopped, humidity raised, temperature adjusted.
- Lid closed from day 18 onward except for a short check at the scheduled time.
- Hatch record filled in within 12 hours of the last chick drying.
When to ask for help, and what to send us
If your hatch is poor and you cannot find the cause in your log, call us on WhatsApp at +233 24 915 1503. Send the log, a photo of two or three unhatched eggs opened at the blunt end, and your machine make and model. We can usually spot the cause from that.
If you are thinking about buying chicks rather than setting your own eggs, first pick a bird with our breed guide, then you can order from the order form or read about our day-old chicks before you decide. For the eggs side of things, the fertile eggs page covers what we can and cannot offer.
Questions farmers ask
How long does it take for a chicken egg to hatch?
A chicken egg takes 21 days from setting to hatch when kept at the right temperature and humidity. Chicks usually start pipping on day 19 or 20 and hatch over about 24 hours. If nothing has happened by day 22, the egg is almost certainly not going to hatch, although you should open one to see why.
What should I check on day 7?
Candle the eggs in a dark room and look for a clear network of veins and a dark embryo spot. Remove eggs that are clear with no veins, and eggs with a blood ring inside the shell. Record how many you removed, because the number tells you how the set started.
Why do I stop turning the eggs on day 18?
By day 18 the chick needs to settle into position, with its head toward the air cell. Turning after this point can tangle the membranes and damage the chick. Stop the turner, mark the tray and raise the humidity for the hatch at the same time.
Should I raise the humidity on day 18?
Yes, for most chicken eggs. The hatch humidity is higher than the setting humidity, and raising it at lockdown helps the membrane soften so the chick can break out. Follow your machine's guide for the exact range, and make the change in one visit rather than in steps.
What if the power goes off during the 21 days?
A short cut of an hour or two rarely ruins a set if the machine is closed and the eggs stay warm. A longer cut needs a backup plan, such as a generator or a solar system, and the plan must be ready before you set. Record the cut in your log with the time and the length.
How do I know whether an egg is dead or still developing?
On day 14, a living embryo fills most of the egg and the veins are dark and crowded. A dead embryo has a dark, sometimes collapsed spot, and the egg may smell bad when cracked. If you are unsure, leave the egg until the next candle rather than removing it on a guess.
Does Ghana's weather change how I follow the 21 days?
The schedule stays at 21 days, but the humidity you need changes with the season. In the harmattan months the air is dry and the water tray empties fast. In the rainy months the room air is damp, so check the air cell and the egg weight, not just the machine's humidity reading.
