Swine Gestation Calculator
Calculate your pig's farrowing due date from the breeding date using the average 114-day gestation period. Free swine pregnancy calculator with farrowing date range, timeline, and progress charts for farmers and breeders.
About This Calculator
The Swine Gestation Calculator helps pig farmers and breeders determine the expected farrowing date for their sows. By entering the breeding or insemination date, the calculator estimates when the sow will give birth using the average swine gestation period of 114 days (with a typical range of 109 to 120 days).
Both domestic and miniature pig breeds have a gestation period of 112 to 120 days. The calculation uses 114 days as the average — the most commonly cited figure by veterinarians and agricultural experts. If a pig farrows before day 109, it is considered an abortion, and piglets born between 109 and 112 days are considered premature. The calculator provides a farrowing date range so you can prepare for the full expected window.
The results include the expected farrowing date, earliest and latest farrowing dates, days along in the pregnancy, days remaining, current week of pregnancy, and the trimester. The timeline and progress charts help visualize the gestation progress. You can share the results with your veterinarian or farm team using the share icon, which saves the breeding date in the URL for easy sharing.
Sows reach sexual maturity at 3 to 12 months old and experience heat every 18 to 24 days. It is recommended to breed a sow during its second or third heat period, not the first. Proper management during gestation — including nutrition, housing, and health monitoring — is essential for maximizing litter size and piglet health. The average litter size ranges from 8 to 14 piglets, with the fourth litter typically being the largest.
Frequently Asked Questions
How long is a pig's gestation period?
Both domestic and miniature pig breeds have a gestation period of 109 to 120 days, with the average being 114 days. If a pig farrows before day 109, it is considered an abortion. Piglets born between 109 and 112 days are considered premature farrowing.
How does the swine gestation calculator work?
Enter the breeding or insemination date of your sow, and the calculator adds 114 days to determine the expected farrowing date. It also calculates a range from 109 to 120 days, plus the number of days along, days remaining, week of pregnancy, and trimester. The calculator works in reverse too: enter the farrowing date to estimate when the sow was bred.
How accurate is the 114-day farrowing estimate?
The 114-day estimate is an average and actual farrowing can vary by a few days. Most sows farrow between 112 and 120 days after breeding. Factors like litter size, sow genetics, age, nutrition, weight, and environment can affect the exact gestation length. Always consult your veterinarian for precise farrowing management.
How many piglets can a sow have per litter?
A sow can give birth to 1 to 20 or more piglets per litter. On average, the fourth litter tends to be the largest. Litter size depends on the sow's genetics, age, nutrition, environment, and parity. Proper nutrition and management during gestation help maximize litter size.
When should I move a pregnant sow to the farrowing pen?
Most farmers move pregnant sows to the farrowing pen about 3 to 7 days before the expected farrowing date (around day 107 to 111 of gestation). Moving her early allows the sow to adjust to the new environment, reduces stress, and lets nesting behavior begin naturally. Signs of imminent farrowing include restlessness, nesting behavior, milk letdown, and vulva swelling.
What are the signs that a sow is pregnant?
The most obvious sign that a sow is pregnant is that she does not return to heat 18 to 24 days after breeding. Other signs include physical changes in belly shape, weight gain, and enlarged mammary glands. Near the farrowing date, the sow will act restless and begin nesting. Ultrasound or blood tests by a veterinarian can confirm pregnancy earlier.
What is the difference between gestation and farrowing?
Gestation is the period of pregnancy from breeding to birth, lasting approximately 114 days in pigs. Farrowing is the actual act of giving birth to piglets. The farrowing date is the expected delivery date calculated from the breeding date using the average gestation period.
How often do sows go into heat?
Sows reach sexual maturity at 3 to 12 months old and then experience heat (estrus) every 18 to 24 days. The heat period lasts 1 to 3 days. It is recommended to breed a sow during its second or third heat, not the first. A sow should be at least 230 days old and weigh around 300 pounds (136 kg) before breeding for optimal litter health.