Pig Gestation Calculator
This pig gestation period calculator finds your sow's expected farrowing date using the proven 3-3-3 rule. The pig gestation period is exactly 3 months, 3 weeks, and 3 days = 114 days. Enter the service date for the exact due date, breed-specific adjustments, and farrowing milestones.
Pig Gestation Calculator
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How to Use This Calculator
Enter the date your sow was bred or artificially inseminated. Select the breed if known — though swine breeds have very similar gestation lengths, ranging from 113–115 days. Click Calculate Due Date to see the expected farrowing date and a full milestone timeline.
The calculator stores your last entry in the browser, making it easy to track multiple sows during peak breeding and farrowing seasons.
Pig Gestation Period — What to Expect
The gestation period for pigs is one of the most predictable in livestock at exactly 114 days (range: 112–116). The question of how long is a pig's gestation period is one of the easiest to remember in all of livestock production — it's exactly 3 months, 3 weeks, and 3 days. The consistency of the gestation period of pigs makes production scheduling highly reliable, which is one reason commercial pig farming operates on tight all-in/all-out cycles.
Days 1–30 (Early gestation): Embryos implant in the uterine horns around days 12–18. This is the most critical period — heat stress, mycotoxins, or nutritional deficiencies during early gestation can cause embryo loss. Feed gestation-specific rations and maintain comfortable temperatures.
Days 30–85 (Mid-gestation): Fetal development continues at a steady pace. Pregnancy can be confirmed by ultrasound at day 25–30 or by return-to-estrus check at day 18–24. Maintain sow body condition score (BCS 3–3.5) throughout this period.
Days 85–114 (Late gestation): Rapid fetal growth occurs, with 60–70% of final birth weight gained in the last 4 weeks. Increase feed intake in the final 2 weeks (flushing) to maximize colostrum and milk production. Move the sow to the farrowing house at day 107–110.
Research from Iowa State University Extension and USDA shows that farrowing rate and litter size are strongly influenced by gilt age at first service, BCS at breeding, and heat stress management — particularly critical in summer months.
Breed-Specific Pig Gestation Periods
| Breed | Avg. Gestation (Days) | Production Type |
|---|---|---|
| Yorkshire | 114 days | Commercial/maternal |
| Duroc | 114 days | Sire/growth |
| Berkshire | 115 days | Heritage/premium pork |
| Hampshire | 114 days | Commercial |
| Landrace | 114 days | Commercial |
| Spotted | 114 days | Commercial |
| Chester White | 114 days | Commercial |
| Poland China | 114 days | Commercial |
| Pietrain | 114 days | Commercial |
| Tamworth | 115 days | Commercial |
| Large Black | 115 days | Commercial |
| Meishan | 114 days | Commercial |
How We Calculate Pig Gestation
The pig gestation calculator uses the formula: Farrowing Date = Service Date + 114 days. The 114-day average is based on extensive swine production data from Iowa State University Extension, USDA NASS, and the National Pork Board. The 3-3-3 mnemonic (3 months + 3 weeks + 3 days) gives the same result.
Frequently Asked Questions
Sources & References
- USDA NASS — Hog and pig production statistics
- Penn State Extension — Swine reproduction and farrowing management
- University of Minnesota Extension — Swine gestation and production
- Merck Veterinary Manual — Porcine reproduction
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GestationCalc Editorial Team
Our editorial team includes animal husbandry specialists, veterinary consultants, and agricultural extension educators. Content is reviewed against peer-reviewed research and guidance from USDA, Penn State Extension, and the Merck Veterinary Manual.
Last reviewed: January 12, 2025