Gestation length by species
| Species | Average | Normal range |
|---|---|---|
| Cow | 283 days | 279–290 |
| Sow | 114 days | 112–116 |
| Goat | 150 days | 145–155 |
| Ewe | 147 days | 144–152 |
| Mare | 340 days | 320–360 |
| Water buffalo | 310 days | 300–320 |
| Jenny (donkey) | 365 days | 350–380 |
| Doe (rabbit) | 31 days | 29–33 |
The calculated date is an approximate window: actual length varies with breed, parity, the sex and number of offspring, nutrition and climate. Start watching the female from the beginning of the range.
Confirm the pregnancy
This calculator assumes the female conceived on the date entered. Have a veterinarian confirm pregnancy by palpation or ultrasound, especially before decisions such as drying off or selling.
Frequently asked questions
How many days is a cow pregnant?
283 days on average (about 9 months and 10 days), with a normal range of 279 to 290 days. Bos indicus breeds and Brown Swiss tend to run a few days longer, Jerseys a few days shorter.
How long is a pig pregnant?
About 114 days: the rule of thumb is "3 months, 3 weeks and 3 days".
What is the heat check date for?
If the female did not settle, she normally comes back into heat after one cycle (about 21 days in cows, sows and goats; 17 in ewes). Watching her on that date tells you whether she needs to be rebred.