Swine Gestation Calculator — Farrowing Date

Background.

This calculator adds the widely published 114-day swine gestation average to a recorded breeding date. The MSD Veterinary Manual lists 114 days for pigs, and Penn State Extension’s June 2026 review independently says pig gestation averages approximately 114 days. It also marks day 110 because Penn State describes days 110–115 as a late-development and farrowing-observation period.

The date is a planning estimate, not proof of pregnancy or a guaranteed delivery appointment. Modern herd data can average closer to 116 days, and genetics, parity, litter and farm practice can affect observed timing. Keep service and pregnancy-check records and follow the herd veterinarian’s farrowing plan.

For breeding on 1 January 2026, day 110 is 21 April and day 114 is 25 April. The calendar uses UTC civil dates, so leap years and daylight-saving changes cannot shift the result.

This page supplies no farrowing-induction, hormone, medication or treatment dosing. Do not use an average date to decide on intervention. Illness, abnormal discharge, distress or farrowing without normal progress requires prompt veterinary assessment.

What is swine gestation calculator?

Swine gestation is the interval from conception to farrowing. Veterinary and current extension sources commonly use about 114 days as a planning average.

How to use this calculator.

1. 01Enter the best recorded breeding or insemination date.
2. 02Use day 110 to begin the farm's established late-gestation observation plan.
3. 03Treat day 114 as an estimate and let veterinary findings and herd records govern.

The formula.

The calculator shifts the recorded civil date by 110 and 114 whole days. It does not infer conception, fit a probability distribution or recommend intervention.

A worked example.

Frequently asked questions.

References& sources.

1. [1]MSD Veterinary Manual's Approximate Gestation Periods table lists pig gestation at 114 days.
2. [2]Penn State Extension, updated June 2026, independently gives an approximately 114-day average.