When to use
- Planning breeding cycles for sow herds
- Scheduling farrowing crate preparation
- Setting up vaccination and nutrition milestones
- Exporting gestation timelines to farm calendars
- Training new farrowing house staff on expected timelines
ToolsConductScience tool
SwineFree in-browser calculator
Sow Gestation & Farrowing Date Calculator.
Calculate expected farrowing date from breeding date. Track milestones, export calendar reminders, and plan your farrowing house prep.
PrivateData stays in your browser
LiveNo sign-up required
Validated2026-04-08
CitableMethods and citation included
Calculator
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Load example gestation data to see the full workflow
Breeding Information
Add or subtract days from the standard 114-day gestation
Do not use for
- As a substitute for veterinary pregnancy confirmation
- For species other than domestic swine (gestation varies by species)
Gilts may farrow early
First-parity sows (gilts) often farrow 1–2 days before the 114-day mark. Use the adjustment field to subtract 1–2 days for gilts.
Record the exact breeding date
Accuracy depends entirely on the breeding date. For AI (artificial insemination), record the date of the last insemination. For natural service with multiple matings, use the first observed breeding.
Plan for a range, not a single date
Normal farrowing range is 112–116 days. Have your farrowing house ready by day 110 to avoid being caught off-guard.
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Method
Calculates farrowing date as breeding date + 114 days (Merck Veterinary Manual standard). Milestones are placed at veterinary-recommended intervals: Day 25 (ultrasound), Day 57 (mid-gestation), Day 90 (late-gestation nutrition), Day 107 (farrowing crate), Day 112 (close watch), and Day 114 (expected farrow). All computation is client-side — no data leaves your browser.
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Validated
Last validated 2026-04-08. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
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How to cite
How to Cite
ConductScience Sow Gestation & Farrowing Date Calculator (v1.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/swine-gestation-farrowing-calculator
Merck Veterinary Manual — Breeding and Gestation of Pigs. Merck & Co., 2023.
Swine Gestation Biology
The domestic pig (*Sus scrofa domesticus*) has a gestation period of 114 days (approximately 3 months, 3 weeks, and 3 days). This is remarkably consistent across all commercial breeds — Yorkshire, Duroc, Hampshire, Berkshire, and crossbreeds.
Key gestational stages:
- Days 1–12: Embryo development and implantation
- Days 13–35: Organogenesis — critical period for fetal development
- Days 35–90: Rapid fetal growth — skeletal and organ maturation
- Days 90–114: Final growth phase — piglets gain 50% of birth weight in the last 3 weeks
Proper nutrition during late gestation (day 90+) directly impacts piglet birth weight and colostrum quality. Sows should transition to lactation-level feed during this period.
Farrowing Management Best Practices
Successful farrowing management depends on preparation and monitoring:
Pre-farrowing (Day 107–112):
- Clean and disinfect farrowing crate before sow entry
- Set heat lamp or mat to maintain piglet zone at 86–90°F (30–32°C) for the first week
- Stock iron dextran (150–200 mg IM for piglets), ear tags, and processing supplies
- Ensure adequate colostrum management plan (all piglets within 6 hours)
During farrowing:
- Average farrowing duration: 2–5 hours for the complete litter
- Interval between piglets: typically 15–20 minutes
- Intervene if no piglet delivered for >45 minutes
- Dry piglets and place under heat source immediately
Post-farrowing (first 72 hours):
- Monitor sow for appetite return and milk production
- Process piglets (iron injection, teeth clipping, tail docking, ear notching) within 24–72 hours
- Watch for crushing — highest risk in first 3 days
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