Horse Gestation Calculator

Plan foaling dates. Prepare for every milestone.

Editable planning examples — individual mares vary.

Breeding & Mare Inputs

Foaling Date & Care Summary

ESTIMATED FOALING DATE—Planning estimate, not a guaranteed delivery date.

—Since entered date

—Remaining

—Timeline complete

Gestation Progress

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Day 0Day 113Day 227Day 340

First thirdMiddle thirdFinal third

Calendar thirds are illustrative, not fetal measurements.

Key Veterinary Milestones

Early scan & twins

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Heartbeat recheck

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EHV-1 reminders

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Foaling location

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Illustrations are educational, not patient scans.

Gestation & Foaling Journey

Illustrated care milestones

Breeding date

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Early veterinary checks

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Late-gestation nutrition

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Foaling location & kit

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Estimated foaling

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Illustrated sequence — milestone spacing is schematic.

Your timeline

Day 0Day 340

Mare Care & Foaling Calendar

Milestone	Date or window	Planning note	As-of status

Care reminders should be individualized with an equine veterinarian. A past planned date does not mean care was completed.

How dates are calculated

Estimated foaling date = entered date + gestation days.
Planning window is a user-defined allowance (e.g. ±10 days), not a statistical confidence interval.
Gestation length varies by individual mare. Consult your veterinarian for personalized care.

Planning assumptions & limitations

Light horse 340, draft 345 and pony 330 days are editable planning examples, not validated breed medians or normal-range guarantees. Individual history and a known ovulation date are more informative.

Breeding is day 0. Calendar arithmetic uses whole date-only days. EHV-1 reminders use calendar months 5, 7 and 9, with end-of-month dates clamped to the last valid day.

Early scan days 14–18 and heartbeat days 25–30 are best interpreted after ovulation; an insemination date may precede ovulation. Veterinary assessment confirms pregnancy, viability and twins.

Nutrition review begins 90 days before the estimate by default. Adjust feeding gradually based on body condition and veterinary advice. EHV-1 and pre-foaling vaccine reminders are not prescriptions; actual product, region and prior vaccination history matter.

Contact your veterinarian promptly for distress, abnormal discharge, premature udder development or concerning labor. Do not wait for a calculated date.

Frequently asked questions

How accurate is the foaling estimate?

It is a planning estimate, not a birth prediction or guarantee. Individual variation and uncertain breeding dates affect accuracy.

Does breed determine gestation length?

Breed can influence gestation, but broad groups overlap. Use mare-specific records; the presets are editable examples.

When should the first scan be scheduled?

A veterinarian commonly assesses pregnancy and twins around days 14–18 after ovulation. Confirm timing with your veterinarian when only a service date is known.

Does this confirm my mare is pregnant?

No. A calendar cannot establish pregnancy, fetal viability, twins or a normal delivery. Veterinary examination is required.

What if the estimated date has passed?

The page shows days past the central estimate. Review records and the mare’s actual status with your veterinarian; do not infer a diagnosis from the date.