Swine Gestation Calculator

Swine gestation calculator will tell you the date of your pig's farrowing.

Last updated: January 8, 2026

CreatorFrank Zhao

Breeding date

Farrowing date

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Farrowing Date

Sunday, 05/10/2026

114 days to go

🐖 Your sow is going to farrow in 114 days!

• Earliest possible farrowing: 05/08/2026
• Latest possible farrowing: 05/16/2026

Earliest Possible

05/08/2026

Day 112

Latest Possible

05/16/2026

Day 120

ℹ️

Swine typically farrow within 112 to 120 days after breeding. Monitor your sow closely as the date approaches.

1Farrowing date

due\_date = breeding\_date + 114

2Earliest possible date

earliest = breeding\_date + 112

3Latest possible date

latest = breeding\_date + 120

breeding_dateBreeding date

due_dateFarrowing date

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Introduction / Overview

The Swine Gestation Calculator estimates your sow’s expected farrowing date based on a breeding date. It also shows a practical earliest/latest window, so you can plan monitoring and preparation in time.

This is useful for pet owners and breeders planning cage setup, monitoring, and vet check timing. If you manage multiple species, you may also like our Rabbit Gestation Calculator.

✅ Quick note: farrowing dates are estimates. Individual variation can shift the true birth day by a few days.

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How to Use / Quick Start Guide

Enter the breeding date

Use the Breeding date field for the day the sow was bred.

Read the estimated farrowing date

The calculator fills in the Farrowing date and shows an earliest/latest window.

Use it in reverse (optional)

If you have a target farrowing date, enter it and the calculator back-solves the breeding date.

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Example (with math):

If the sow was bred on Oct 1, an average farrowing estimate uses a 114-day gestation.

\text{Oct 1} + 114\ \text{days}

=

\text{Jan 23}

The earliest/latest range is computed the same way using $112$ and $120$ days.

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Calculation Method / Formula

The calculator uses a standard average swine gestation length of 114 days, plus a realistic “normal range” window. In the calculator:

Core estimate

\text{Farrowing Date} = \text{Breeding Date} + 114\ \text{days}

(average; individual pregnancies vary)

Window shown in the results:

Earliest possible: $\text{Breeding Date} + 112\ \text{days}$
Latest possible: $\text{Breeding Date} + 120\ \text{days}$

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Real-World Examples / Use Cases

Example 1: Planning cage setup

Situation: You record a breeding date of Sep 10 and want a clear prep window.

\text{Sep 10} + 114\ \text{days}

=

\text{Jan 2}

How to use it: Begin preparing the cage and supplies at least a week before the “earliest possible” date.

Example 2: Breeding backward from a target farrowing date

Situation: You want piglets arriving around Mar 15. When should breeding occur?

\text{Mar 15} - 114\ \text{days}

=

\text{Nov 21}

How to use it: Plan pairing dates around the target, then confirm pregnancy and re-check the window.

Example 3: Interpreting “earliest” and “latest”

Situation: Your sow was bred on Nov 5. What window should you watch most closely?

Earliest

\text{Nov 5} + 112

Average

\text{Nov 5} + 114

Latest

\text{Nov 5} + 120

How to use it: Treat the window as your monitoring period. If you’re outside the range, consider that your breeding date might be off (or consult a vet).

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Common Scenarios / When to Use

Best times to use it

Right after breeding (record keeping)
Before setting up a birthing area
When scheduling help / night checks
Planning vaccinations and nutrition changes

When it may be less accurate

If the breeding date is uncertain (unknown service)
If multiple breeding events occurred across many days
If health issues or extreme stress affected the pregnancy

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Tips & Best Practices

•Write down the date immediately: a “small” recording error of 3–5 days is the most common reason farrowing dates feel off.
•Use the full window: plan your monitoring around the earliest/latest dates, not only the average.
•Prepare supplies early: clean cage area, fresh bedding, towels, and a plan for monitoring.
•Don’t ignore red flags: if the sow is clearly in trouble, prolonged labor, or shows sudden illness, contact a veterinarian.

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Pro Tip: If you’re timing multiple breeding groups, run the calculator for each group date and write the window on a barn calendar. Small workflow changes often beat perfect math.