Pig Gestation Calculator
Estimate your sow or gilt farrowing date from the breeding date using the classic pig gestation rule of 3 months, 3 weeks, and 3 days.
The common average for pig pregnancy planning: 3 months, 3 weeks, and 3 days.
Sow Farrowing Date Calculator
Enter the breeding date and choose a gestation estimate. The calculator shows the estimated farrowing date, early and late window, farrowing area preparation date, and close-watch date.
Your Pig Gestation Result
This is an estimate only. Farrowing can occur earlier or later depending on sow, gilt, litter size, genetics, health, and management.
Pig Gestation Chart
| Milestone | Approximate Timing | What It Means | Management Note |
|---|---|---|---|
| Breeding Date | Day 0 | The sow or gilt was bred. | Record animal ID, boar/semen source, and breeding date. |
| Return-to-Heat Check | About 18–24 days | A return to heat may indicate the animal is not pregnant. | Monitor records and rebreed if appropriate. |
| Early Gestation | Days 1–35 | Pregnancy establishment period. | Avoid unnecessary stress and sudden management changes. |
| Mid Gestation | Days 36–80 | Steady fetal development. | Monitor body condition and feeding program. |
| Late Gestation | Days 81–114 | Rapid fetal growth and udder development may occur. | Prepare farrowing supplies and housing. |
| Expected Farrowing | About day 114 | Average pig farrowing date estimate. | Watch closely and seek veterinary help for abnormal labor. |
What Is a Pig Gestation Calculator?
A pig gestation calculator is a farrowing date tool that estimates when a pregnant sow or gilt may give birth based on the breeding date. The calculator adds a selected gestation length to the breeding date. The common pig pregnancy rule is 3 months, 3 weeks, and 3 days, which is about 114 days.
This tool is useful for pig farmers, homesteaders, small livestock owners, 4-H families, veterinary support teams, and students learning about swine reproduction. It helps plan farrowing crates or pens, bedding, heat lamps, piglet supplies, colostrum management, observation schedules, and late-gestation feeding.
The result should be used as a planning estimate, not a guaranteed farrowing date. Sows and gilts may farrow earlier or later depending on age, parity, litter size, genetics, nutrition, season, and health. Contact a veterinarian if the sow appears distressed, has prolonged labor, abnormal discharge, weakness, fever, or difficulty delivering piglets.
How to Use the Pig Gestation Calculator
- Select the breeding date.
- Choose the gestation estimate. The default is 114 days.
- Select whether the animal is a sow, gilt, or confirmed pregnancy.
- Click “Calculate Farrowing Date.”
- Use the preparation and close-watch dates to organize farrowing supplies.
Important: Pig farrowing dates are estimates. Gilts and high-risk animals should be monitored closely, especially near the expected farrowing window.
Pig Pregnancy Timeline
| Stage | Approximate Days | Possible Signs | Planning Action |
|---|---|---|---|
| After Breeding | Days 0–24 | Few visible signs; watch for return to heat. | Record breeding date and check heat cycle behavior. |
| Early Pregnancy | Days 25–45 | Pregnancy may not be obvious externally. | Maintain steady feed, water, and low stress. |
| Mid Pregnancy | Days 46–80 | Body condition becomes important. | Review nutrition and housing. |
| Late Pregnancy | Days 81–107 | Abdomen enlarges and mammary development may begin. | Prepare farrowing area and supplies. |
| Farrowing Window | About days 112–116 | Nesting, restlessness, milk, vulva swelling, reduced appetite. | Observe closely and prepare for piglet care. |
Signs a Sow Is Getting Close to Farrowing
Behavior Signs
A sow or gilt close to farrowing may become restless, start nesting, paw or root bedding, lie down and rise often, or become less interested in feed.
Physical Signs
Common signs include udder filling, milk letdown, swollen vulva, abdominal dropping, increased breathing, and visible contractions as labor begins.
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Pig Gestation Calculator FAQs
How long are pigs pregnant?
Pigs are commonly pregnant for about 114 days, often remembered as 3 months, 3 weeks, and 3 days.
What is a pig farrowing date?
The farrowing date is the estimated date when a pregnant sow or gilt is expected to give birth to piglets.
How does this pig gestation calculator work?
It adds the selected gestation length, usually 114 days, to the breeding date and shows an estimated farrowing date with early and late planning windows.
Can a sow farrow before 114 days?
Yes. Some sows may farrow before the average estimate, so this calculator includes an early planning window.
Can a sow go past 114 days?
Yes. Some sows farrow later than 114 days. Contact a veterinarian if the sow appears distressed, overdue with concerning signs, or unable to progress during labor.
When should I prepare the farrowing area?
Many producers begin preparing the farrowing area and supplies one to two weeks before the expected farrowing date.
Is this calculator useful for gilts?
Yes, but gilts may need closer observation because it is their first litter and farrowing behavior may be less predictable.
Is this calculator the same as a swine gestation calculator?
Yes. Pig gestation calculator, swine gestation calculator, and sow farrowing date calculator usually refer to the same type of due date planning tool.