Pig Birthing Date Calculator: Calculate Expected Farrowing Dates

The "three months, three weeks, three days" rule is one of the most widely known facts in pig farming — and it's remarkably accurate. Pig gestation is 114 days on average, and most sows farrow within a day or two of this. The Pig Birthing Date Calculator takes the mating or AI date and calculates the expected farrowing date, along with key pre-farrowing management milestones.

The calculator returns the expected farrowing date based on a 114-day gestation, a countdown from today, and suggested dates for moving the sow to the farrowing pen (day 110), washing and disinfecting the sow (day 111), and setting up the farrowing environment. A notes panel covers what to prepare: a heat lamp positioned for piglets, bedding materials, colostrum, farrowing kit, and veterinary contact details.

The 114-day average gestation period (3 months, 3 weeks, 3 days) is the standard used across all UK pig production literature and is published by AHDB Pork and the National Pig Association. Individual sows may farrow one to three days early or late; sows carrying very large or very small litters may occasionally deviate further from the average.

Enter the date the sow was mated or artificially inseminated. The expected farrowing date and preparation milestones will appear. Add the farrowing date to your farm calendar and set reminders for the pre-farrowing management checks. For sows with a history of early or late farrowing, adjust your monitoring window accordingly.