A fertilized egg in ARK: Survival Ascended won’t hatch unless you hold it at the right temperature — get it wrong and the egg steadily loses health and dies. Incubation is the gateway to breeding, so getting it right matters. This guide covers fertilized vs unfertilized eggs, the temperature ranges by category, every way to control temperature, and how to keep a baby alive the moment it hatches.
Egg temperature ranges
Each species’ egg falls into a temperature band. Use this as a guide, then confirm the exact range with the incubation tool before you commit ACs or torches.
| Category | Temperature | Example species |
|---|---|---|
| Very Warm | 35°C+ | Wyvern, Giganotosaurus, Magmasaur |
| Warm | ~25–35°C | Rex (32–34°C), Trike, Stego, Therizino (26–32°C) |
| Mild | ~15–25°C | Raptor, Allosaurus, Carbonemys |
| Cool | ~0–15°C | Argentavis (12–13.5°C), Quetzal, Pteranodon |
Fertilized vs unfertilized eggs
Creatures drop unfertilized eggs regularly — these are food and kibble ingredients; they never hatch. A fertilized egg only appears after a male and female of the same species mate. Only fertilized eggs incubate into babies, and only fertilized eggs need temperature control.
Why temperature matters
Drop the egg and read its status — it tells you whether it’s too hot or too cold. While the temperature is wrong, the egg’s health drops; if it hits zero, the egg is lost. Your only job during incubation is to bring the surrounding temperature into the correct band and hold it there until the egg hatches.
Ways to control temperature
- Air Conditioners — the cleanest, most reliable method. A ring of ACs holds a stable temperature for almost any species; add or remove ACs to fine-tune. This is what most breeders use for a permanent hatchery.
- Standing Torches / Campfires — cheap heat for cold-climate eggs; place more or fewer to dial in the temperature.
- Incubator — the late-game device that lets you set an exact temperature and even improves mutation odds; ideal for serious breeding.
- Location & weather — the ambient climate does half the work. Hatch desert eggs in a hot biome and snow eggs in the cold, then top up with ACs or torches.
- Dimetrodon — radiates insulation; sitting an egg near tamed Dimetrodons can hold temperature naturally.
Incubation time & hatching
Once the temperature is right, the egg incubates over a set time, then hatches into a baby that immediately needs food in its inventory — so be ready with meat or berries before it pops. From there you’re into the raising and imprinting phase covered in our breeding & imprinting guide. Get exact ranges and times from our free ARK Egg Incubation tool.
Frequently asked questions
What temperature does a Rex egg need in ARK?
About 32–34°C — in the “Warm” band. A ring of air conditioners in a hatchery holds it easily; in a hot biome you may need fewer ACs or some torches to fine-tune. Therizino eggs sit just below at 26–32°C.
How do I hatch a Wyvern egg?
Wyvern eggs are “Very Warm” (35°C+) and need a large bank of air conditioners — around 15 or more — or a hot biome plus extra heat. An Incubator set to the exact temperature is the cleanest solution. Until then, keep the egg in your inventory so it doesn’t decay while you build the hatchery.
Why is my ARK egg losing health?
The temperature is outside the egg’s range — too hot or too cold. The egg’s status text tells you which; adjust ACs, torches or location until it reads as incubating. If health hits zero the egg is lost, so correct it quickly or hold the egg in your inventory while you set up.
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