Gorilla Gestation Calculator
This gorilla gestation calculator finds the expected birth date instantly. Select your subspecies and enter the mating date to calculate the gestation period and view key milestones.
Quick Answer
The gestation period for gorillas averages 257 days, with a normal range of 250–265 days — the closest to human gestation of any great ape. Enter your mating date above for an exact expected birth date.
Gorilla Gestation Calculator
Free tool — no signup required
Closest Gestation to Humans of Any Great Ape
At 257 days, gorilla gestation is remarkably close to the human gestation period of 280 days — closer than chimpanzees (235 days) and nearly matching orangutans (260 days). This similarity reflects how closely related the great apes are evolutionarily, and gorilla reproductive biology has long been studied as a comparative model for understanding primate — including human — pregnancy and development.
Silverback-Led Troops
A silverback is the dominant adult male gorilla — named for the distinctive patch of silver-gray hair that develops on his back with maturity — who leads and protects a troop of females and their offspring. He fathers most or all of the troop's infants and plays an active protective role even though females do the actual infant care, defending the troop from predators and rival males, and mediating disputes within the group.
Infant Development
Gorilla infants are born essentially helpless, much like human newborns, and cling constantly to their mother's fur for the first several months. They begin riding on their mother's back around 4 to 5 months of age as they gain strength and coordination, and remain nutritionally dependent on nursing until weaning around 3 years old. This extended, intensive care period is central to why gorillas reproduce so slowly.
Slow Reproduction & Conservation Status
Female gorillas typically give birth only once every 4 to 6 years, one of the slowest reproductive rates of any great ape — a direct consequence of the extended infant care period. This slow reproduction makes gorilla population recovery from any decline especially difficult.
Mountain gorillas number only around 1,000 individuals, and the Cross River gorilla subspecies has fewer than 300 remaining, making it one of the rarest great apes on Earth. Habitat loss, poaching, disease, and past civil conflict across their Central African range have all contributed to declines, though dedicated conservation efforts have helped mountain gorilla numbers slowly rise in recent decades.
Gorilla Intelligence
Gorillas display remarkable intelligence — they use tools in the wild (such as using sticks to measure water depth), maintain complex social structures within their troops, and show clear signs of empathy, grief, and self-awareness. Some captive gorillas, most famously Koko, have even been taught to use sign language to communicate with humans, offering rare insight into great ape cognition.
Gestation by Gorilla Subspecies
| Subspecies | Avg. Gestation | Notes |
|---|---|---|
| Mountain Gorilla | 257 days | Endangered — only ~1,000 remain |
| Western Lowland Gorilla | 257 days | Most common in captivity |
| Eastern Lowland Gorilla | 257 days | Also called Grauer's gorilla |
| Cross River Gorilla | 257 days | Critically endangered — fewer than 300 remain |
How Gorilla Gestation Compares to Other Great Apes
| Species | Avg. Days | Vs. Gorilla |
|---|---|---|
| Human | 280 days | 23 days longer |
| Orangutan | 260 days | 3 days longer |
| Gorilla | 257 days | — |
| Chimpanzee | 235 days | 22 days shorter |
See our chimpanzee gestation calculator.
How We Calculate Gorilla Gestation
The gorilla gestation calculator uses the formula: Birth Date = Mating Date + 257 days. The average is derived from published primatology and zoo husbandry research.
Frequently Asked Questions
Sources & References
- IUCN Red List — Gorilla conservation status
- Merck Veterinary Manual — Primate reproduction
Related Calculators
Cattle & Cow Gestation Calculator
283 days avg
Goat Gestation Calculator
150 days avg
Dog Gestation Calculator
63 days avg
Pig Gestation Calculator
114 days avg
Rabbit Gestation Calculator
31 days avg
Sheep Gestation Calculator
147 days avg
Horse Gestation Calculator
336 days avg
Llama Gestation Calculator
350 days avg
Donkey Gestation Calculator
365 days avg
Cat Gestation Calculator
65 days avg
Deer Gestation Calculator
201 days avg
Elephant Gestation Calculator
645 days avg
Giraffe Gestation Calculator
457 days avg
Mare Gestation Calculator
340 days avg
Mice Gestation Calculator
20 days avg
Guinea Pig Gestation Calculator
65 days avg
Hamster Gestation Calculator
16 days avg
Alpaca Gestation Calculator
340 days avg
Ferret Gestation Calculator
42 days avg
Beef Cattle Gestation Calculator
283 days avg
Chicken (Egg Incubation) Gestation Calculator
21 days avg
Duck (Egg Incubation) Gestation Calculator
28 days avg
Dog (Whelping) Gestation Calculator
63 days avg
Pig (Farrowing) Gestation Calculator
114 days avg
Goat (Kidding) Gestation Calculator
150 days avg
Goose (Egg Incubation) Gestation Calculator
30 days avg
Turkey (Egg Incubation) Gestation Calculator
28 days avg
Quail (Egg Incubation) Gestation Calculator
17 days avg
Sheep (Lambing) Gestation Calculator
147 days avg
Horse (Foaling) Gestation Calculator
340 days avg
Cattle (Calving) Gestation Calculator
283 days avg
Rabbit (Kindling) Gestation Calculator
31 days avg
Chinchilla Gestation Calculator
111 days avg
Rat Gestation Calculator
22 days avg
Gerbil Gestation Calculator
25 days avg
Hedgehog Gestation Calculator
35 days avg
Bison Gestation Calculator
277 days avg
Camel Gestation Calculator
400 days avg
Zebra Gestation Calculator
375 days avg
Wolf Gestation Calculator
63 days avg
Dairy Cattle Gestation Calculator
279 days avg
Ball Python Gestation Calculator
57 days avg
Corn Snake Gestation Calculator
60 days avg
Leopard Gecko Gestation Calculator
52 days avg
Bearded Dragon Gestation Calculator
65 days avg
Tortoise Gestation Calculator
75 days avg
Red-Eared Slider Gestation Calculator
75 days avg
Chameleon Gestation Calculator
175 days avg
Green Iguana Gestation Calculator
105 days avg
Crested Gecko Gestation Calculator
90 days avg
Blue Tongue Skink Gestation Calculator
100 days avg
King Snake Gestation Calculator
55 days avg
Boa Constrictor Gestation Calculator
110 days avg
Monitor Lizard Gestation Calculator
165 days avg
Python (All Species) Gestation Calculator
70 days avg
Gecko (All Species) Gestation Calculator
65 days avg
Guppy Gestation Calculator
26 days avg
Molly Fish Gestation Calculator
65 days avg
Platy Fish Gestation Calculator
28 days avg
Swordtail Fish Gestation Calculator
28 days avg
Betta Fish Gestation Calculator
3 days avg
Goldfish Gestation Calculator
5 days avg
Angelfish Gestation Calculator
2 days avg
Discus Fish Gestation Calculator
2 days avg
Koi Fish Gestation Calculator
4 days avg
Endler Guppy Gestation Calculator
23 days avg
Cherry Shrimp Gestation Calculator
30 days avg
Tilapia Gestation Calculator
14 days avg
Lion Gestation Calculator
110 days avg
Tiger Gestation Calculator
103 days avg
Leopard Gestation Calculator
96 days avg
Cheetah Gestation Calculator
93 days avg
Chimpanzee Gestation Calculator
235 days avg
Polar Bear Gestation Calculator
240 days avg
Brown Bear Gestation Calculator
220 days avg
Hippopotamus Gestation Calculator
240 days avg
Rhinoceros Gestation Calculator
462 days avg
Kangaroo Gestation Calculator
35 days avg
Koala Gestation Calculator
35 days avg
Giant Panda Gestation Calculator
135 days avg
Reindeer Gestation Calculator
228 days avg
Moose Gestation Calculator
235 days avg
Dolphin Gestation Calculator
365 days avg
Whale Gestation Calculator
365 days avg
Bear (All Species) Gestation Calculator
220 days avg
Otter Gestation Calculator
65 days avg
All Gestation Periods
Complete comparison chart
GestationCalc Editorial Team
Our editorial team includes animal husbandry specialists, veterinary consultants, and agricultural extension educators. Content is reviewed against peer-reviewed research and guidance from USDA, Penn State Extension, and the Merck Veterinary Manual.
Last reviewed: September 4, 2026