Cow Gestation Calculator
A cow's gestation period is about 283 days, or roughly 9 months and 1 week, though it ranges from 279 to 292 days depending on breed and individual animal.
How to use the cow 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. Pick the breed so the calculator uses the right average gestation length.
- 3. Plan around the range. Use the earliest and latest dates and the milestone timeline to schedule checks, feed changes and preparation of the calving area.
Calculate a calf due date
Bull calves are typically carried slightly longer than heifer calves.
Estimated calving date
Saturday, 8 May 2027
Earliest
4 May 2027
Latest
17 May 2027
0 of 283 days elapsed
Milestone timeline
| Day | Milestone | Date |
|---|---|---|
| 30 | Pregnancy check by ultrasound | 28 Aug 2026 |
| 223 | Dry off (60 days pre-calving) | 9 Mar 2027 |
| 253 | Pre-calving vaccinations | 8 Apr 2027 |
| 273 | Move to calving pen | 28 Apr 2027 |
| 283 | Expected calving | 8 May 2027 |
How long is a cow's gestation period?
The average is 283 days from breeding to calving, about 9 months and 1 week. Anything between 279 and 292 days is normal, and a typical litter is 1 calf. Treat the calculated date as the middle of that window rather than a fixed appointment.
Cow gestation table: breeding date to calving date
Breeding dates one week apart with the matching calving date at 283 days.
| Breeding date | Expected calving date |
|---|---|
| 29 Jul 2026 | 8 May 2027 |
| 5 Aug 2026 | 15 May 2027 |
| 12 Aug 2026 | 22 May 2027 |
| 19 Aug 2026 | 29 May 2027 |
| 26 Aug 2026 | 5 Jun 2027 |
| 2 Sept 2026 | 12 Jun 2027 |
| 9 Sept 2026 | 19 Jun 2027 |
| 16 Sept 2026 | 26 Jun 2027 |
| 23 Sept 2026 | 3 Jul 2027 |
| 30 Sept 2026 | 10 Jul 2027 |
| 7 Oct 2026 | 17 Jul 2027 |
| 14 Oct 2026 | 24 Jul 2027 |
How breed changes the calving date
Selecting a breed swaps the average the calculator uses, which can move the calving date by more than a week.
| Breed | Average days | Difference |
|---|---|---|
| Average | 283 | — |
| Holstein | 279 | -4 days |
| Jersey | 279 | -4 days |
| Angus | 281 | -2 days |
| Hereford | 285 | +2 days |
| Simmental | 287 | +4 days |
| Charolais | 287 | +4 days |
| Brown Swiss | 290 | +7 days |
| Brahman | 292 | +9 days |
Working backwards from a target calving date
If you want calfs on the ground in a particular week, switch the calculator to target date mode and enter the date you are aiming for. It subtracts 283 days to give the breeding date to book, plus the earliest and latest service dates that still land inside your window.