Estimate farrowing date for your sow based on breeding date
Swine gestation is highly consistent at 114 days (3 months, 3 weeks, 3 days). Range: 110–118 days.
Powered by Toolraxy
Founder & CEO, Toolraxy
Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.
User Ratings:
ADVERTISEMENT
ADVERTISEMENT
Breeding pigs requires precise record-keeping, and knowing your sow’s farrowing date allows you to prepare farrowing crates, adjust feeding programs, schedule vaccinations, and ensure assistance is available when piglets arrive. This swine gestation calculator estimates farrowing dates based on breeding date, using the famously consistent 114-day gestation period of pigs.
The average sow gestation lasts exactly 114 days — remembered easily as “3 months, 3 weeks, and 3 days.” This remarkable consistency makes swine gestation one of the most predictable among livestock species. The normal range is 110 to 118 days, but most sows farrow within 24 hours of day 114. Miniature and potbellied pig breeds average 113 days — slightly shorter than standard commercial breeds.
This calculator does more than predict a farrowing date. It shows you days since breeding, days remaining, current pregnancy stage, and displays key swine pregnancy milestones from breeding through farrowing. Pig producers use this information to time pregnancy checks (day 25-30 ultrasound), schedule the move to farrowing crates (day 110), and prepare for piglet processing. Powered by Toolraxy — all calculations happen in your browser.
Select your breed type — Choose Standard Swine (114 days) or Miniature/Potbellied (113 days), or Custom
Enter custom days (if selected) — Set any gestation length between 108-120 days
Enter the breeding date — Select the date of natural breeding or AI
Click Calculate — Results update automatically as you change inputs
View the estimated farrowing date — See predicted delivery date with color coding
Check days remaining — Know how much preparation time you have left
See the current stage — Understand early, mid, or late pregnancy
Review key milestones — Use the timeline grid for management planning
The swine gestation calculator adds breed-specific gestation days to the breeding date, then calculates time-based metrics relative to today’s date.
| Breed Type | Gestation Days | Example Breeds |
|---|---|---|
| Standard Swine | 114 days | Yorkshire, Duroc, Hampshire, Landrace, Berkshire, Large White |
| Miniature / Potbellied | 113 days | Vietnamese Potbellied, Mini Pig, KuneKune |
| Custom | 108–120 days | User-defined |
Swine gestation is famously consistent:
3 months (approximately 90 days)
3 weeks (21 days)
3 days (3 days)
Total: 114 days
Farrowing Date Formula:
Days Since Breeding:
Days Since = Today's Date − Breeding Date
Days Remaining:
Days Remaining = Farrowing Date − Today's Date
Pregnancy Stage Determination:
Trimester Length = Gestation Days ÷ 3 Early Pregnancy: Days Since ≤ Trimester Length Mid Pregnancy: Days Since > Trimester Length AND ≤ Trimester Length × 2 Late Pregnancy: Days Since > Trimester Length × 2 Late Pregnancy Final 2 Weeks: Days Remaining ≤ 14
Scenario: A Yorkshire sow (standard breed) was bred on April 1, 2025. Today is May 15, 2025.
Step-by-step calculation:
Identify breed type: Standard Swine → 114 days gestation
Breeding date: April 1, 2025
Calculate farrowing date: April 1 + 114 days = July 24, 2025
Days since breeding: April 1 to May 15 = 44 days
Days remaining: May 15 to July 24 = 70 days
Trimester calculation: 114 ÷ 3 = 38 days per trimester
Days since (44) > 38 and > 76? No (44 ≤ 76) → Mid Pregnancy
Check approaching status: 70 days remaining > 10 → no orange warning
Interpretation: The sow is in mid-pregnancy, 44 days along. According to the milestone grid:
Embryo attachment completes at Day 35-45 — she is at the end of this window
Visible belly growth will begin at Day 60-70 (approximately June 1-11)
Rapid fetal growth occurs at Day 80-90 (late June)
The producer has 70 days to prepare. The orange warning color will appear when 10 days remain (July 14, 2025) — signaling close observation. At Day 100-110 (July 10-20), the sow will develop udder (bag up) and show nesting behavior.
Miniature breed example: A Potbellied pig bred on April 1, 2025. Select “Miniature / Potbellied Pig” → 113 days. Farrowing date = July 23, 2025 (1 day earlier than standard).
A producer has a Landrace sow bred on August 1. Using the calculator with Standard Swine (114 days), due date is November 23.
August 25 (Day 24): Watch for return to heat — none observed
August 30 (Day 29): Schedule ultrasound for pregnancy confirmation
October 1 (Day 61): Increase feed to 2.7 kg/day for gestation
October 15 (Day 75): Notice belly visibly enlarging
November 1 (Day 92): Udder development begins (bagging up)
November 10 (Day 101): Prepare farrowing crate, gather supplies
November 15 (Day 106): Move sow to farrowing crate
November 20 (Day 111): Milk let-down observed (colostrum dripping)
November 22 (Day 113): Sow restless, nesting behavior
November 23 (Day 114): 5 AM — farrowing begins; 12 piglets delivered by 8 AM
The producer followed the milestone timeline, with the orange warning at day 114 triggering final observation.
Saves time — Instant farrowing date calculation using the 3-3-3 rule
Breed-specific presets — Standard Swine (114d), Miniature/Potbellied (113d)
Custom gestation — Set any length between 108-120 days
Stage tracking — Know early, mid, or late pregnancy with final 2-week alert
Visual milestones — Reference grid shows key management benchmarks
Farrowing warning — Orange color at 10 days remaining signals close observation
Free to use — No premium version, subscriptions, or registration
Private — All calculations in your browser; no data transmitted
Accessible on any device — Works on phones, tablets, and computers
Countdown display — Days remaining helps with farrowing crate timing
Shareable results — Copy or share timeline with veterinarian
The calculator provides estimates based on the standard 114-day gestation. Swine gestation is highly consistent — over 90% of sows farrow within day 112-116. Miniature breeds average 113 days. Individual sows may vary by ±2-3 days. Use the calculator as a planning tool and watch physical signs (bagging up, milk let-down) for actual timing.
The “3-3-3” rule is a memory aid for swine gestation duration:
3 months (approximately 90 days)
3 weeks (21 days)
3 days (3 days)
Total: 114 days
This rule makes farrowing date estimation easy without a calculator: add 3 months to breeding date, then add 3 weeks and 3 days.
Without a known breeding date, farrowing date estimation is difficult. A veterinarian can estimate gestation stage by:
Ultrasound with fetal measurements (Days 25-90)
Observation of udder development and physical signs (late pregnancy)
For future pregnancies, record breeding dates accurately.
Prolonged gestation beyond 118 days is uncommon. If a sow reaches Day 118 without farrowing:
Verify breeding date accuracy
Consider possibility of small litter (1-3 piglets)
Consult veterinarian — prolonged gestation increases risk of stillbirths and farrowing difficulty
Most healthy sows farrow within 110-118 days.
Standard commercial swine breeds average 114 days gestation. Miniature breeds (Vietnamese Potbellied, KuneKune) average 113 days — approximately 1 day shorter. The reason is not fully understood but may relate to smaller litter sizes (miniature pigs typically have 4-6 piglets vs. 10-14 in standard breeds).
Schedule ultrasound at Day 25-35 post-breeding. This window allows:
Confirmation of pregnancy
Detection of non-pregnant sows for rebreeding
Estimation of litter size (experienced ultrasonographers)
The calculator’s milestone “Day 25–30: Ultrasound confirmation” reminds producers of this critical window.
Contact a veterinarian immediately if you observe:
Vaginal bleeding or discharge before Day 100
Sow off feed for more than 24 hours
Fever, lethargy, or signs of systemic illness
Straining or signs of premature labor (before Day 110)
Abnormal discharge (green, brown, foul-smelling)
Set up 1-2 weeks before due date:
Clean and disinfect farrowing crate thoroughly
Ensure floor is non-slip (rubber mats or textured surface)
Install heat lamp (90-95°F / 32-35°C) for piglet creep area
Position within 18 inches of crate floor for piglets
Check that sow can stand and lie comfortably
Have farrowing supplies within reach
Clean water available at all times
The Day 101 milestone signals farrowing crate preparation.
Most reliable signs:
Milk let-down — colostrum drips or sprays from teats when udder pressed — 12-24 hours before
Udder distension — tight, full mammary glands (“bagging up”) — 5-10 days before
Nesting behavior — sow gathers straw, rearranges bedding — 24-48 hours before
Vulva swelling and reddening — 1-7 days before
Restlessness — frequent position changes, pawing — 2-6 hours before
Milk secretion (spontaneous) — teats drip colostrum — 2-12 hours before
The calculator’s orange warning at 10 days remaining helps producers start watching for signs.
Piglets should nurse within the first 2 hours of life — colostrum intake is critical for passive immunity. Target intake: 200-250 ml of colostrum per piglet within the first 6 hours. Piglets that do not nurse within 12 hours have significantly higher mortality risk. Ensure piglets find teats; assist weak piglets. The calculator focuses on gestation — for piglet care resources, consult swine management guides.
ADVERTISEMENT
ADVERTISEMENT
