Ovatekly · Guides
Candling eggs, day by day.
What you are looking for on day 7, day 14 and day 18, what a clear egg and a blood ring look like, and when to take an egg out.
Short answer
Candle chicken eggs on day 7, again on day 14, and once more on day 18 before lockdown. A growing egg shows a dark spot with red veins spreading out like a spider; an egg that glows evenly is infertile or died very early; a red ring means the embryo has died. Remove clear eggs and eggs with blood rings (Illinois Extension). Candling for less than 10 minutes does not harm the embryo (Texas A&M AgriLife).
Four patterns
What a candled egg looks like
Drawn illustrations, to show the patterns. Real eggs are less tidy, and brown or speckled shells hide more.
Before you start
How to candle without harming the egg
- Work in a dark room and hold the egg with its large end against the light (Illinois Extension).
- Be quick, and keep hot lights brief. Cooling for less than 10 minutes during candling does not harm the embryo, but even a brief period at 104 °F (40 °C) kills it (Texas A&M).
- Wash your hands before you touch the eggs; dirt and oil carry germs into the shell (Texas A&M).
- White and pale eggs are easier to read than brown or speckled ones (Texas A&M). White eggs can be checked from day 3; brown ones from day 5 or 6 (Illinois Extension).
- Mark each egg in pencil and write down what you saw. Illinois Extension suggests a candling chart and checking every few days, not every day.
- Put each egg back the way it was, small end lower than the large end (Texas A&M).
Sources: Texas A&M AgriLife Extension, Incubating and Hatching Eggs (POSC-PU-018, 2022); Illinois Extension, Candling Eggs.
The schedule
Day by day, for chicken eggs
| When (chicken eggs) | What you should see | What to do |
|---|---|---|
| Day 3 (white shells) or day 5 to 6 (brown) | A small reddish area with blood vessels extending away from it (Illinois Extension). | Nothing yet if you are unsure: dark shells are hard to read this early. |
| Day 7 | A dark spot in the large end with a faint outline of firm, distinct blood vessels around it (Texas A&M). | Remove clear eggs and eggs with blood rings or streaks (Illinois Extension). |
| Day 14 | A dark mass filling most of the egg and a clear air cell. | Remove any egg that has stopped developing or smells. |
| Day 18 | Eventually only a dark mass and the air cell (Texas A&M). The air cell should be clearly larger than on day 7. | Last look. Then lockdown: the lid stays shut until the hatch. |
Sources: Texas A&M AgriLife Extension, Incubating and Hatching Eggs (POSC-PU-018, 2022); Illinois Extension, Candling Eggs. Other species keep the same order on their own calendars: lockdown is day 15 for Japanese quail and day 25 for ducks and turkeys. See how long eggs take to hatch.
Decisions
What you see, and what to do about it
| What you see | What it usually means | What to do |
|---|---|---|
| Even glow, perhaps a yolk shadow, no veins | An infertile egg, or one that died very early. Texas A&M: an infertile egg transmits light brightly. | Remove it. With a brown or speckled shell, look again a few days later first. |
| Dark spot with red veins spreading out | A live, developing embryo. | Back into the incubator, same way up. |
| A red ring or streak of blood | The embryo has died: the blood draws away from it and forms a ring (Illinois Extension). | Remove it. |
| A dark spot stuck to the shell, no vessels | A dead embryo. Once it dies it stops growing and the blood system fades (Texas A&M). | Remove it. |
| A dark mass, sharp line at the air cell | A late-stage embryo, as expected from about day 14. | Leave it. |
| Cloudy, murky, leaking or smelling | A rotting, contaminated egg. Dirty eggs can burst in the incubator (Texas A&M, Table 3). | Remove it gently, then wash your hands. |
Sources: Texas A&M AgriLife Extension, Incubating and Hatching Eggs (POSC-PU-018, 2022), text and Table 3; Illinois Extension, Candling Eggs.
Expect some clear eggs. Texas A&M puts infertile eggs at ten percent or more of a typical setting. Taking out clear and dead eggs is not just tidying: it removes possible sources of contamination from the incubator. If you have doubts about an egg, ask someone who has candled before.
The light
What to candle with
Texas A&M notes that many people candle with a small flashlight that can be focused, and that commercial candlers cost little. What matters is a bright, cool light you can press the egg against, in a dark room.
Every Ovatekly incubator has a candling light built in and clear trays, so you do not need anything else for the eggs inside it. If you hatch in another machine or want a light you can hold, the Ovatekly Candler (US$15) is a pocket lamp with nine cool LEDs under a soft cup that the egg sits on.
Not sure about an egg during an Ovatekly hatch? Photograph it against the light and email it to contact@ovatekly.com with the day you are on. A person looks at it with you.
Questions
Questions people ask
When should you candle eggs?
What does an infertile egg look like when you candle it?
What does a blood ring mean?
Does candling hurt the eggs?
Can you candle brown, blue or speckled eggs?
Can I candle during lockdown?
Sources
Where the numbers come from
- Texas A&M AgriLife Extension, Incubating and Hatching Eggs (POSC-PU-018, 2022), Candling section and Table 3.
- Illinois Extension, Candling Eggs.
- Kansas State University, Incubation and Reproduction (poultry Q&A).
Updated October 17, 2026. Written by the Ovatekly team. Temperatures, humidity levels and incubation periods on this page are general references from the extension publications named beside them, not Ovatekly specifications.
More from the hatch guides
A person for the whole hatch.
Every Ovatekly comes with Hatch Support: email a photo of your display or a candled egg to contact@ovatekly.com and a real person answers, from the day you set your eggs until they hatch.