If you're incubating chicken eggs, you've likely heard the advice:
🕯️ “Candle the eggs on Day 7.”
But this often leads to confusion for beginners and even seasoned poultry keepers:
👉 Should I candle at the start or end of Day 7?
👉 What should I expect to see inside the egg?
👉 What if nothing is visible—did I do something wrong?
In this complete guide, we'll explain everything you need to know about candling chicken eggs, including the best timing, what to look for, how to candle correctly, and what to do after candling.
Let’s break it down for success.
📅 What is Day 7 in Chicken Egg Incubation?
The term “Day 7” refers to the seventh full day of incubation. But here's where the misunderstanding happens:
🔄 Day 0 vs. Day 1
- When you place eggs in the incubator, that day is Day 0.
- Day 1 starts after the first 24 hours of incubation.
- So, if you set your eggs on Monday morning, Day 1 starts Tuesday morning, and Day 7 ends the following Monday morning.
✅ Candling is best done at the end of Day 7 or beginning of Day 8, when embryo development is more visible.
🔍 Why Candle Chicken Eggs?
Candling is a crucial step in monitoring embryo health and improving hatch rates. By shining a bright light into the egg, you can:
- Detect if the egg is fertile or infertile
- Check embryo development and movement
- Spot blood vessels, veining, or early death
- Remove bad eggs early to avoid contamination
This reduces the risk of exploding or rotten eggs that can damage your hatch.
🕯️ How to Candle Chicken Eggs (Step-by-Step)
✅ You Will Need:
- A dark room
- A bright LED egg candler or flashlight (cool light only!)
- Clean hands
🐣 Candling Steps:
- Turn off the incubator briefly.
- Take one egg at a time (minimize cooling).
- Shine the light into the blunt (wider) end of the egg.
- Rotate slowly to examine the contents.
- Record your observations and return the egg quickly.
⚠️ Don’t candle for more than 30 seconds per egg. Overhandling can lower hatch rates.
📸 What You Should See When Candling on Day 7 (End)
By the end of Day 7, here’s what you’re likely to observe:
🔸 Healthy Fertile Egg:
- A dark embryo spot (developing chick)
- Clear blood vessels like a spider web
- Movement if the embryo is alive
- A visible air cell on the top end
🔸 Infertile Egg:
- Looks completely clear
- No blood vessels, no dark spot
- May resemble an unincubated egg
🔸 Early Embryo Death:
- Blood ring (a circular red line)
- No movement or growth
- Faint odor may start developing
✅ Pro Tip: Use a pencil to mark infertile eggs so you can double-check at Day 10 or discard early.
🔁 Should You Candle More Than Once?
Yes, for the best hatching success, you should candle your chicken eggs at least twice during incubation:
| Day | Purpose |
|---|---|
| Day 7 (end) | Check for fertility and initial development |
| Day 14 | Confirm active embryo growth |
| Optional Day 18 | Light check before lockdown (optional) |
Do NOT candle after Day 18 as the chick prepares to hatch and movement can be dangerous.
⚠️ Why Candling Too Early is a Mistake
If you candle too early, such as on the morning of Day 7, you may wrongly assume an egg is infertile or dead because:
- The embryo is still tiny and hard to see
- Veining may be too faint
- Movement may not be visible
➡️ This is why waiting until the end of Day 7 gives you more accurate results.
🛠️ Candling Tips for Better Hatch Rates
- Use a powerful candler – avoid phone lights or weak flashlights
- Don’t crack or shake eggs during candling
- Be quick to avoid cooling the egg
- Track your observations using a notebook or hatch chart
- Discard any rotten, leaking, or smelly eggs immediately
💡 Did you know? Candling helps prevent exploding eggs, which can ruin your entire batch by spreading bacteria.
❓ Common Questions About Candling Chicken Eggs
Q: Can I candle daily?
A: It's not recommended. Candle only on Day 7 and Day 14 unless needed.
Q: What if I see no veins?
A: Wait a day or two. Sometimes development is slightly delayed.
Q: Can I reuse infertile eggs?
A: No. Always discard infertile eggs safely. Don’t consume incubated eggs.
🐥 Conclusion: Candling on Day 7 – End is Best
To summarize:
✅ Day 7 candling should happen at the end of the 7th day, or the morning of Day 8
✅ Look for veins, movement, and embryo shadows
✅ Remove infertile or dead eggs to improve hatch success
✅ Handle eggs gently and return them to the incubator quickly
Candling is both fascinating and important—it’s your window into life forming inside the shell.