Farrowing date calculator
Pig gestation calculator
A sow is pregnant for about 114 days — three months, three weeks and three days — and most farrow between day 110 and day 117. Enter the date she was served or inseminated to see the farrowing window; for a boar running with a group, enter the first and last day he was in.
Pig farrowing date calculator
Enter one breeding date, or the first and last day the male ran with the group. Work back from a target birth date with “Plan backward”.
- Earliest reference
- Sun, Mar 28, 2027
- Central reference
- Thu, Apr 1, 2027
- Latest reference
- Sun, Apr 4, 2027
- Outer breeding window
- —
- Reference breeding band
- —
Pigs: 2026-12-08 + 110 days = 2027-03-28 · + 114 days = 2027-04-01 · 2026-12-08 + 117 days = 2027-04-04 · window 8 days
Nothing you enter leaves your browser. Dates are planning references, not guarantees.
Example: a gilt inseminated on December 8
A gilt is bred by AI on December 8, 2026. The pig profile adds 110, 114 and 117 days:
Earliest farrowing: Sun, Mar 28, 2027
Expected farrowing: Thu, Apr 1, 2027
Latest in the usual range: Sun, Apr 4, 2027
Move to the farrowing pen by about: Tue, Mar 23, 2027 (five days before the earliest date)
A boar with a small group. If the boar ran with three sows from January 4 to January 9, 2027, the batch could farrow from Sat, Apr 24, 2027 to Thu, May 6, 2027, with most litters expected Wed, Apr 28, 2027 – Mon, May 3, 2027.
Which pig gestation length does the calculator use?
- Minimum
- 110 days
- Reference
- 114 days
- Maximum
- 117 days
Both limits come from Penn State Extension’s farrowing guide (“most sows will farrow between 110 and 117 days”) and the 114-day reference from its article on how gestation shapes piglet outcomes. The MSD Veterinary Manual also lists 114 days for pigs. Litters can arrive outside this window, as the Livestock Gestation Tracker app notes on its pig profile.
What makes a sow farrow early or late?
| Situation | Gestation (days) | Source |
|---|---|---|
| Most sows | 110–117 | Penn State Extension |
| Average | about 114 | Penn State Extension; MSD Veterinary Manual |
| Sows with smaller litters | usually 113–115 | Penn State Extension |
| Highly prolific modern genetics | can reach 115–120 | Penn State Extension |
| Warning sign of a difficult farrowing | over 116 | Purdue University |
We did not find a university source that gives a separate figure for gilts versus older sows, so the calculator uses one profile for both. If your own records show a consistent difference, add a custom profile in the app.
What are the signs a sow is about to farrow?
Purdue’s farrowing guide gives a useful timeline:
- 12 to 24 hours before: the mammary glands secrete milk, the sow becomes restless and starts building a nest — pawing and rooting at the bedding.
- About 6 hours before: milk flows freely from the teats.
- 30 to 90 minutes before: straining begins and blood-tinged fluid, sometimes with meconium, is passed.
Penn State adds faster breathing and trembling in the last hours to minutes.
How should I prepare the farrowing pen?
- Clean and disinfect the farrowing crate or pen and let it dry before the sow moves in
- Move her in one to five days before the earliest date (Purdue), earlier if your system needs it
- A heat source and creep area for piglets, separate from the sow
- Towels, iodine for navels, OB gloves and lubricant, and a record sheet for each litter
- Pre-farrowing vaccinations on the schedule your veterinarian sets for your herd
When does a farrowing need help?
Purdue recommends stepping in when more than an hour passes between piglets, and calling the veterinarian for a prolapse, heavy bleeding, a suspected twisted uterus or a retained placenta. A sow straining hard with no piglet, or one that is past day 116 with no sign of labour, also deserves a call.
Livestock Gestation Tracker is an organizational aid, not veterinary advice. Reference dates vary by animal, breed, pregnancy and management conditions. Use your own records and your veterinarian or a qualified livestock professional for care decisions.
Sources
Questions people ask
How long is a pig pregnant?
About 114 days — the old rule of thumb is three months, three weeks and three days. Penn State Extension says most sows farrow between 110 and 117 days.
What is the farrowing date for a sow bred on December 8?
With 114 days she is due around April 1, 2027. The 110–117-day range puts farrowing between March 28 and April 4, 2027.
Do modern sows farrow later?
Sometimes. Penn State Extension notes that sows with small litters usually farrow at 113 to 115 days, while highly prolific modern genetics can push gestation to 115 to 120 days. Purdue lists a gestation over 116 days as one warning sign of a difficult farrowing.
When should a sow go into the farrowing pen?
Purdue’s guidance is one to five days before she is due; Penn State mentions moving sows up to ten days before. Count back from the earliest date in the window so an early litter is not born in the gestation pen.
How long should farrowing take?
Purdue says the whole litter usually arrives in less than two and a half hours, with piglets coming about every 15 to 30 minutes according to Penn State. More than an hour between piglets is the point to intervene or call for help.