Gestation Calculator
Normal gestation range: 112–116 days. Larger litters may farrow 1–2 days early; smaller litters may go 1–2 days late.
How Pig Gestation Works
The average gestation period for a pig is 114 days — often remembered as "3 months, 3 weeks, and 3 days." This applies to all domestic pig breeds, from Landrace and Yorkshire to Duroc and Berkshire. Once a sow or gilt is successfully bred, the clock starts ticking toward the expected farrowing (birthing) date.
During the first two-thirds of pregnancy the embryos develop relatively slowly. Most fetal growth happens in the final 30–40 days, which is why sow nutrition in late gestation is critical for piglet birth weight.
Factors That Affect Gestation Length
While 114 days is the textbook average, actual gestation can range from 112 to 116 days. Several factors influence where a particular sow falls within that window:
- Litter size — Larger litters tend to arrive 1–2 days earlier, while smaller litters may go a day or two past the due date.
- Breed — Some breeds, such as Meishan, naturally carry slightly longer than European breeds.
- Parity — First-litter gilts sometimes farrow a day later than experienced sows.
- Environment — Heat stress or sudden changes in housing can trigger earlier farrowing.
Signs of Approaching Farrowing
Starting around day 110, watch for these indicators that farrowing is near:
- Udder development and milk letdown (milk can be expressed from teats 12–24 hours before farrowing).
- Vulva swelling and relaxation of the pelvic ligaments.
- Nesting behavior — the sow may repeatedly rearrange bedding.
- Restlessness, increased breathing rate, and loss of appetite on the day of farrowing.
Quick Gestation Reference Table
Use the table below for a quick month-to-month estimate. Exact dates depend on the specific breeding day.
| Bred In | Expected Farrowing |
|---|---|
| January | April – May |
| February | May – June |
| March | June – July |
| April | July – August |
| May | August – September |
| June | September – October |
| July | October – November |
| August | November – December |
| September | December – January |
| October | January – February |
| November | February – March |
| December | March – April |
Frequently Asked Questions
How long is a pig pregnant?
A pig's pregnancy lasts an average of 114 days (approximately 3 months, 3 weeks, and 3 days). The normal range is 112 to 116 days.
Can I breed a gilt at any age?
Gilts should reach at least 7–8 months of age and weigh around 260–300 lbs (120–135 kg) before their first breeding. Breeding too early can reduce litter size and cause farrowing difficulties.
How soon after farrowing can a sow be bred again?
Most sows are rebred 5–7 days after weaning, which typically occurs at 21–28 days of lactation. This means a sow can produce roughly 2.3–2.5 litters per year.
Does the 114-day rule apply to mini pigs and pot-bellied pigs?
Yes. Miniature breeds such as Vietnamese pot-bellied pigs also have a gestation period of approximately 114 days, though individual variation of 111–115 days is common.