Calculator Input
Enter the sow record and breeding details below. Results appear above this form immediately after submission.
Formula Used
- Expected farrowing date = Breeding date + Gestation days.
- Farrowing window start = Breeding date + (Gestation days − Window days).
- Farrowing window end = Breeding date + (Gestation days + Window days).
- Progress percentage = (Days elapsed ÷ Gestation days) × 100.
- Rule of thumb = Swine gestation is commonly summarized as 3 months, 3 weeks, and 3 days, which equals about 114 days.
How to Use This Calculator
- Enter the sow ID and herd or batch name.
- Select the breeding method used for the record.
- Use the service date that best represents the breeding event.
- Keep 114 days for standard planning or enter a custom value.
- Set a farrowing window to model practical early or late delivery variation.
- Choose a reference date to check current gestation progress.
- Submit the form to view the result panel, milestone table, and chart above the form.
- Use the CSV or PDF buttons to save the calculated schedule.
Example Data Table
| Sow ID | Breeding Date | Gestation Days | Expected Farrowing | Parity | Method |
|---|---|---|---|---|---|
| SOW-101 | Jan 02, 2026 | 114 | Apr 26, 2026 | 2 | Artificial Insemination |
| SOW-118 | Feb 14, 2026 | 114 | Jun 08, 2026 | 4 | Timed AI |
| GILT-22 | Mar 01, 2026 | 114 | Jun 23, 2026 | 0 | Natural Service |
Frequently Asked Questions
1) How long is normal swine gestation?
Most swine pregnancies average about 114 days. Producers often remember it as 3 months, 3 weeks, and 3 days. Individual animals can farrow a little earlier or later.
2) Why does the calculator allow custom gestation days?
Herd records sometimes use slightly different planning values. Custom days help match observed herd performance, management preferences, or veterinary guidance while keeping the due-date logic simple.
3) Can a sow farrow outside the expected date?
Yes. A practical farrowing window helps account for normal biological variation. Nutrition, environment, litter size, and recording accuracy can all shift the actual farrowing date slightly.
4) Does parity change the due date calculation?
Parity does not directly change the calendar formula here. It is stored because herd managers often compare gilts and older sows when reviewing productivity, health, and farrowing patterns.
5) Which breeding date should I enter after multiple services?
Use the date your farm treats as the official service date. Many herds use the last insemination or final confirmed mating when calculating the projected farrowing schedule.
6) When should pregnancy checks happen?
Common management checkpoints are around days 21, 28, and 35. Exact timing depends on technique, equipment, and veterinary protocol, so herd-specific practice may differ slightly.
7) Why is crate movement shown before the due date?
Many farms move sows to the farrowing area before expected delivery. This supports acclimation, monitoring, sanitation, and staff readiness during the final gestation days.
8) Is this calculator a veterinary diagnosis tool?
No. It is a planning and recordkeeping tool. Health concerns, abnormal discharge, missed farrowing, or suspected pregnancy loss should always be reviewed with a qualified veterinarian.