Gorilla Gestation Calculator
Last updated
A gorilla's gestation period is about 257 days, or roughly 8 months and 1 week, though it ranges from 250 to 270 days depending on breed and individual animal.
Calculate a infant due date
Estimated birthing date
Saturday, 19 June 2027
Earliest
12 Jun 2027
Latest
2 Jul 2027
0 of 257 days elapsed
Milestone timeline
| Day | Milestone | Date |
|---|---|---|
| 0 | Conception | 5 Oct 2026 |
| 30 | A urine pregnancy test can confirm pregnancy in zoos | 4 Nov 2026 |
| 180 | Belly and breasts noticeably larger | 3 Apr 2027 |
| 257 | Expected birth, around eight and a half months after conception | 19 Jun 2027 |
How to use the gorilla gestation calculator
- 1. Choose what you know. Enter the breeding date to get a due date, or switch to the target due date mode to work backwards to the breeding date you need.
- 2. Refine the inputs. The calculator uses the 257-day average for this species.
- 3. Plan around the range. Use the earliest and latest dates and the milestone timeline to schedule checks, feed changes and preparation of the birthing area.
How long is a gorilla's gestation period?
The average is 257 days from breeding to birthing, about 8 months and 1 week. Anything between 250 and 270 days is normal, and a typical litter is 1 infant. Treat the calculated date as the middle of that window rather than a fixed appointment.
Gorilla gestation table: breeding date to birthing date
Breeding dates one week apart with the matching birthing date at 257 days.
| Breeding date | Expected birthing date |
|---|---|
| 5 Oct 2026 | 19 Jun 2027 |
| 12 Oct 2026 | 26 Jun 2027 |
| 19 Oct 2026 | 3 Jul 2027 |
| 26 Oct 2026 | 10 Jul 2027 |
| 2 Nov 2026 | 17 Jul 2027 |
| 9 Nov 2026 | 24 Jul 2027 |
| 16 Nov 2026 | 31 Jul 2027 |
| 23 Nov 2026 | 7 Aug 2027 |
| 30 Nov 2026 | 14 Aug 2027 |
| 7 Dec 2026 | 21 Aug 2027 |
| 14 Dec 2026 | 28 Aug 2027 |
| 21 Dec 2026 | 4 Sept 2027 |
Working backwards from a target birthing date
If you want infants on the ground in a particular week, switch the calculator to target date mode and enter the date you are aiming for. It subtracts 257 days to give the breeding date to book, plus the earliest and latest service dates that still land inside your window.