How long is a pig pregnant?
Your sow carries her piglets about 114 days. Pig farmers keep it in their heads as 3 months, 3 weeks and 3 days, and that is close enough to count on. A litter is usually 12 to 13 piglets, and she nurses them until weaning at around 21 days.
Farrowing date = breeding date + 114 days
The 3-3-3 rule, worked out
Three months, three weeks and three days is 3 × 30 + 3 × 7 + 3 = 114 days on a 30 day month. Count it off on a real calendar and you land within a day or two of that, so when you need a firm date for a bred sow, use the calculator above.
Planning dates (guide)
These are general guides, not fixed rules. Your vet and your own herd plan come first.
| Day | What to plan |
|---|---|
| About 21 | A sow that was not settled usually returns to heat about three weeks after breeding, so this is the first heat check |
| About 28 or later | A vet can confirm pregnancy by ultrasound |
| About 105 to 110 | Clean and bed the farrowing pen so the sow can settle in before she farrows |
| About 114 | Farrowing |
| About 21 days after farrowing | Piglets are commonly weaned at about this age on commercial farms |
Sample farrowing dates
| Bred | Farrowing date | Normal window |
|---|---|---|
| Thu, Jan 1, 2026 | Sat, Apr 25, 2026 | Wed, Apr 22, 2026 to Tue, Apr 28, 2026 |
| Sun, Mar 1, 2026 | Tue, Jun 23, 2026 | Sat, Jun 20, 2026 to Fri, Jun 26, 2026 |
| Fri, May 1, 2026 | Sun, Aug 23, 2026 | Thu, Aug 20, 2026 to Wed, Aug 26, 2026 |
| Wed, Jul 1, 2026 | Fri, Oct 23, 2026 | Tue, Oct 20, 2026 to Mon, Oct 26, 2026 |
| Tue, Sep 1, 2026 | Thu, Dec 24, 2026 | Mon, Dec 21, 2026 to Sun, Dec 27, 2026 |
| Sun, Nov 1, 2026 | Tue, Feb 23, 2027 | Sat, Feb 20, 2027 to Fri, Feb 26, 2027 |
That window is a 3 day planning guide on either side of day 114, not a published range. Most sows farrow within a few days of the expected date, and your vet can tell you when an overdue sow is worth worrying about. To compare other species, see the animal gestation periods chart.
Frequently asked questions
How long is a pig pregnant?
About 114 days, or 3 months, 3 weeks and 3 days.
How many piglets does a sow have?
A sow or gilt usually has 12 to 13 piglets per litter on commercial farms. Heritage breeds and young gilts often have fewer.
When are piglets weaned?
On commercial farms piglets are weaned at about 21 days of age. Small farms often wait longer.
How do I calculate a farrowing date by hand?
Add 3 months, 3 weeks and 3 days to the breeding date, or add 114 days.
Sources
More gestation calculators
Cow Gestation Calculator
Calving date by breed, with the normal window.
Horse Gestation Calculator
Foaling date with the 320 to 370 day window.
Goat Gestation Calculator
Kidding date for dairy, meat and pygmy goats.
Sheep Gestation Calculator
Lambing date for ewes, with the normal window.
Dog Pregnancy Calculator
Whelping date with week-by-week milestones.
Cat Pregnancy Calculator
Kitten due date and stages of cat pregnancy.