Edited by Jennifer Bryant · Poultry breeder, Animal Science graduate, and Poultry Nerds Podcast co-host.
Candling means shining a bright light through an egg in a dark room so you can see what's growing inside. Around one week into incubation, a developing egg shows a dark spot with thin red veins spreading out like a spider web. It's one of the most exciting moments of hatching.
Don't worry, there are no actual candles involved anymore. Old-timers used candlelight. Today, a small, bright flashlight does the job.
What You Need
A small, bright light (an egg candler or a strong LED flashlight)
A dark room
Clean, dry hands
About a minute per egg
Step by Step
Darken the room. The darker, the better.
Wash and dry your hands. Eggshells have tiny pores, and clean hands are kind to the eggs.
Hold the light to the big end of the egg. That's where the air cell sits.
Tilt the egg gently until you can see inside.
Look, then put it back quickly. Eggs cool fast outside the incubator, so keep it short.
What You Might See
Around one week: A dark spot (the embryo) with red veins reaching out. Sometimes you'll see it wiggle!
Later in incubation: The egg looks darker and fuller as the chick grows. The air cell at the big end gets larger.
A clear egg: It may not be fertile, or it may have stopped growing very early. If you're not sure, check again in a few days before removing it.
A red ring: A thin red ring with no web of veins often means the embryo stopped growing.
Tips for Success
Brown and speckled eggs are harder to see through than white ones. Be patient.
Candle only a few times during incubation, not every day.
Never candle during the last few days before hatch, when the incubator should stay closed.
Remove eggs that have clearly stopped growing, especially if they smell bad, so they don't spoil the batch.
Want to learn what every stage looks like? Incubation Masterclass walks you through it step by step. Need eggs to start with? Find hatching eggs at Hatching Egg Directory.
