Pig Farrowing Calculator
This pig farrowing calculator predicts your sow's expected farrowing date instantly. Enter the breeding date to calculate the farrowing window, then use the guides below to prepare the farrowing crate, know the labour stages, recognize complications, and give newborn piglets the best possible start.
Quick Answer
Sows farrow approximately 114 days after breeding — the classic “3 months, 3 weeks, 3 days” rule — with a normal range of 112–116 days. Enter your sow's breeding date above to calculate the exact expected farrowing date and start your preparation countdown.
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Farrowing Supplies Checklist
Have these on hand and within reach before your sow's expected farrowing date — most farrowings happen with little warning once labour starts.
| Supply | Purpose |
|---|---|
| Clean, dry towels | Drying piglets immediately after birth to prevent chilling |
| Iodine (7% tincture) | Navel dip to reduce infection risk |
| Heat lamp or heat pad | Warming the piglet creep area to 85–90°F |
| Digital thermometer | Monitoring the sow's temperature for fever or the pre-labour drop |
| OB lubricant & long OB gloves | Assisting a stuck piglet if needed |
| Needle-tooth nipper / clippers | Clipping needle teeth, if your operation practices this |
| Iron injection (iron dextran) | Preventing anemia — piglets are born with very low iron reserves |
| Scale | Weighing each piglet at birth and tracking early growth |
| Notebook or log | Recording birth order, times, and any interventions |
| Vet's emergency number | Posted where you can see it — most farrowings happen overnight |
Setting Up the Farrowing Crate or Pen
Move the sow to the farrowing crate or a clean farrowing pen about 3–5 days before her expected farrowing date so she has time to settle into the new environment before labour begins.
- A crate confines the sow's body movement, reducing the risk of her accidentally lying on and crushing piglets — a leading cause of piglet mortality in loose-housed systems
- Provide a piglet creep area along the sides, outside the sow's reach, where piglets can nurse and retreat safely
- Add a heat lamp or heating pad in the creep area only — sows prefer cooler temperatures (60–70°F) while newborn piglets need warmth (85–90°F) for their first days
- Use clean, dry bedding and ensure continuous access to water — intake rises sharply during farrowing and lactation
- Clean and disinfect the crate or pen before move-in to reduce disease exposure to the newborn litter
- If using a pen rather than a crate, add solid guard rails a few inches off the floor and walls so piglets have an escape gap when the sow lies down
Signs Farrowing Is Imminent (Final 24–48 Hours)
- Udder development: the udder fills and enlarges starting 2–3 days before farrowing.
- Milk let-down: being able to hand-express milk is one of the most reliable short-term predictors, typically appearing 12–24 hours before farrowing.
- Nest-building behavior: even sows in a crate will paw at and arrange bedding, a strong instinctive behavior right before labour.
- Vulva swelling and reddening.
- Reduced appetite in the final 12–24 hours.
- Restlessness — repeated standing and lying, tail twitching, and general agitation as contractions begin.
- Mucus or bloody discharge can appear shortly before the first piglet, though heavy or foul discharge is a warning sign, not a normal one.
The Stages of Labour
| Stage | Typical Timing | What Happens |
|---|---|---|
| Stage 1 — Pre-labour | 2–12 hours | Restlessness, nesting, cervical dilation; no piglets visible yet |
| Stage 2 — Active farrowing | 2–4 hours (up to 6) | Piglets are delivered, typically 15–20 minutes apart |
| Interval between piglets | 15–20 min (normal) | Longer than 30–45 minutes with straining warrants a check |
| Stage 3 — Placenta | Within 4 hours of last piglet | Afterbirth is passed, sometimes in sections during Stage 2 |
When to Intervene or Call the Vet
- More than 45–60 minutes of straining passes without a piglet being delivered
- More than 30–45 minutes pass between piglets while the sow still appears to be straining
- The sow shows signs of exhaustion, fever, or stops contracting before the litter is clearly finished
- A piglet is visibly stuck in the birth canal
- Foul-smelling or discolored discharge appears
- The placenta hasn't passed within 4–6 hours of the last piglet
- Stage 1 (restless, nesting, no visible piglets) drags on for more than 12–24 hours without progressing to active labour
Newborn Piglet Care in the First Hours
- Dry each piglet with a clean towel right after birth — chilling is a leading cause of early piglet loss, especially in cold weather.
- Get warmth immediately. Move dried piglets to the heated creep area away from the sow while she continues farrowing.
- Dip or spray the navel with iodine to reduce infection risk.
- Ensure nursing within the first few hours — ideally within 6 hours at the very latest. Colostrum intake in this window is critical for immune protection; assist weak piglets onto a teat if needed.
- Clip needle teeth if your operation practices this, to reduce injury to the sow's udder and littermates.
- Iron injection around day 2–3 of life — piglets are born with very low iron reserves and sow milk is a poor iron source, so an injection prevents anemia during rapid early growth.
- Watch the runt or weakest piglets closely in the first 24–48 hours, since they're at the highest risk of failing to nurse adequately.
Common Farrowing Complications
- Dystocia: difficult birth from a piglet malpositioned in the birth canal, an oversized piglet, or an unusually narrow pelvis. Signs include prolonged straining without progress — this needs OB assistance or a vet.
- Uterine inertia: weak or stopped contractions, often from an exhausted uterus in large litters, low calcium, or an overweight sow. Labour stalls partway through with piglets still undelivered.
- Savaging and crushing risk: some first-time sows (gilts) react aggressively to newborns, and any sow lying down carelessly in a pen without adequate guard rails can crush piglets — a crate or well-guarded pen substantially reduces this risk.
- Stillbirths: more common toward the end of a long farrowing, especially after 4+ hours of active labour, as later-born piglets face a higher risk of oxygen deprivation.
- MMA (mastitis-metritis-agalactia): a post-farrowing syndrome combining udder inflammation, uterine infection, and reduced milk supply, usually appearing within 12–72 hours of farrowing — watch for fever, a hot or swollen udder, and hungry, restless piglets.
Post-Farrowing Care for the Sow
- Nutrition: gradually increase feed over the first few days after farrowing to reach full lactation intake by about day 5–7; a nursing sow needs considerably more energy and water than during pregnancy.
- Watch for mastitis: check the udder daily for heat, swelling, or hard quarters, and monitor piglets for signs they aren't getting enough milk.
- Uterine health: normal post-farrowing discharge (lochia) tapers off within a few days; discharge that is heavy, foul-smelling, or persists longer than a week can signal metritis and warrants a vet check.
- Rebreeding timeline: most sows return to estrus 4–7 days after weaning (commonly 3–4 weeks post-farrowing in commercial systems), so plan the next breeding around your weaning schedule.
Want the Full Pregnancy Timeline?
This calculator focuses on farrowing — the birth event itself. For a complete week-by-week pregnancy timeline, nutrition guidance, and checkpoint schedule from breeding through farrowing, see our full pig gestation calculator.
Frequently Asked Questions
How do I calculate when my sow will farrow?
Add 114 days to the breeding or AI date — the famous '3 months, 3 weeks, 3 days' rule for pig gestation, with a normal range of 112–116 days. Use the calculator above for an exact farrowing date so you know when to start watching for labour signs and have supplies ready.
What supplies do I need for farrowing?
A basic farrowing supply kit includes: clean, dry towels for drying piglets, iodine (7% tincture) for navel dips, a heat lamp or heat pad for the creep area, a digital thermometer, obstetric (OB) lubricant and long OB gloves in case you need to assist, clean scissors or a needle-tooth nipper if your operation clips teeth, an iron injection (e.g., iron dextran) for piglets, a scale to weigh newborns, a notebook to log birth order and times, and your veterinarian's emergency number posted where you can see it.
How do I set up the farrowing crate or pen?
Move the sow to the farrowing crate or a clean farrowing pen about 3–5 days before her expected date so she can settle in. Provide a piglet creep area along the sides, outside the sow's reach, kept at 85–90°F (29–32°C) with a heat lamp — while the sow herself prefers cooler temperatures around 60–70°F. Use clean, dry bedding, disinfect the crate before move-in, and ensure continuous access to water, since her intake rises sharply during farrowing and lactation.
What are the signs that farrowing is imminent?
In the final 24–48 hours, watch for udder filling and enlargement, restlessness and nest-building even in a crate (pawing and arranging bedding), a swollen and reddened vulva, reduced appetite, and mucus discharge. Milk let-down — being able to hand-express milk from the teats — is the single most reliable short-term predictor, typically appearing 12–24 hours before the first piglet arrives.
What are the stages of labour in a sow?
Stage 1 (pre-labour, roughly 2–12 hours) involves restlessness, nesting, and cervical dilation with no visible piglets yet. Stage 2 (active farrowing) is the delivery of piglets, usually spaced 15–20 minutes apart, with the whole litter typically born within 2–4 hours (occasionally up to 6). Stage 3 is the passage of the placenta (afterbirth), normally within 4 hours of the last piglet, sometimes passed in sections throughout Stage 2.
When should I intervene or call the vet during farrowing?
Call your vet if: more than 45–60 minutes of straining passes without a piglet being delivered; more than 30–45 minutes pass between piglets with continued straining; the sow shows signs of exhaustion, fever, or stops contracting before the litter is clearly finished; you see a piglet visibly stuck in the birth canal; foul-smelling or discolored discharge appears; or the placenta hasn't passed within 4–6 hours of the last piglet. When in doubt, call — early intervention prevents stillbirths and protects the sow.
What is MMA and why does it matter after farrowing?
MMA (mastitis-metritis-agalactia) is a post-farrowing syndrome combining udder inflammation, uterine infection, and reduced or absent milk production, usually appearing within 12–72 hours of farrowing. It's a leading cause of piglet starvation and early mortality in the litter, so watch the sow closely in the first few days for fever, a hot or swollen udder, reduced appetite, and piglets that seem constantly hungry or restless — all are reasons to call the vet promptly.
How soon should piglets nurse after birth, and why does colostrum matter?
Every piglet should nurse within the first few hours of birth, ideally within 6 hours at the very latest. Piglets are born with almost no antibody protection of their own, since the pig placenta blocks most maternal antibodies before birth, so colostrum is essentially their entire source of passive immunity. The gut's ability to absorb those antibodies drops sharply after about 12 hours and largely closes by 24–36 hours, making early nursing one of the most important factors in litter survival.
Sources & References
- Merck Veterinary Manual — Porcine parturition, dystocia, and neonatal care
- USDA — Swine production data
- Penn State Extension — Swine reproduction and farrowing management
- University of Minnesota Extension — Farrowing management and sow care
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Kanika
Researched and reviewed by Kanika, founder of GestationCalc. All gestation data is verified against primary veterinary and agricultural sources before publication.
Last reviewed: September 8, 2026