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Animal Gestation Calculator — Dog, Cat, Cattle, Goat, Horse

Estimate a due date for dogs, cats, cattle, goats, or horses from the breeding date. Species-specific earliest/expected/latest gestation windows.

Updated
Expected Due Date (Dog, 63-day average)
October 18, 2026
Earliest (58 days)
October 13, 2026
Latest (68 days)
October 23, 2026

0 days since breeding

Gestation length varies naturally by individual, litter size, and breed within each species — the earliest/latest range reflects normal variation, not a medical concern. If your animal goes noticeably past the latest date shown, or shows signs of distress at any point, contact your veterinarian.
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Reference Values

Last verified:
Category Range What It Means Status
Dog 58–68 days (avg. 63) Counted from the day of successful mating/ovulation; litter size can shift timing slightly (larger litters sometimes arrive a little early). Good
Cat 58–67 days (avg. 64) Cats are induced ovulators, so timing depends on when mating actually triggered ovulation. Good
Cattle (cow) 279–290 days (avg. 283) Bull calves are typically carried slightly longer than heifer calves. Good
Goat 145–155 days (avg. 150) Larger litters (twins/triplets) tend to arrive a few days earlier than singles. Good
Horse (mare) 320–370 days (avg. 340) One of the widest natural ranges of any common livestock/pet species — a 30+ day spread from average is not unusual. Okay

Source: Gestation-length ranges aggregated from the Merck Veterinary Manual's Approximate Gestation Periods table and Kentucky Equine Research's equine gestation data.

Worked Examples

Dog Bred on March 1

Species
Dog
Breeding Date
March 1
Due window April 28 – May 8, expected May 3

63-day average gestation (58–68 day range) counted from the breeding date.

Cat Bred on June 10

Species
Cat
Breeding Date
June 10
Due window Aug 7 – Aug 16, expected Aug 13

64-day average gestation (58–67 day range).

Cow Bred on January 15

Species
Cattle
Breeding Date
January 15
Due window Oct 21 – Nov 1, expected Oct 25

283-day average gestation (279–290 day range) — cattle have one of the longest and most consistent gestation periods of common livestock.

Mare Bred on May 1

Species
Horse
Breeding Date
May 1
Due window March 17 – April 6 (next year), expected April 6

340-day average gestation with a wide 320–370 day natural range — mares have the least predictable due date of common gestation species.

How to Use This Calculator

  1. 1

    Select your species

    Dog, cat, cattle, goat, or horse — each uses its own species-specific gestation range.

  2. 2

    Enter the breeding or mating date

    The date of successful breeding, mating, or artificial insemination.

  3. 3

    Read your due date window

    Shows the expected due date plus the earliest and latest dates within the normal range for that species.

What Each Value Means

Expected Due Date (date)
The breeding date plus the species' average gestation length in days.
Earliest / Latest Due Date (date)
The breeding date plus the species' minimum and maximum typically observed gestation length, representing the normal range rather than a hard cutoff.

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Frequently Asked Questions

How accurate is a gestation due date estimate?
It's a window, not a guarantee. Every species has a natural range around its average — dogs and cats vary by about 10 days, cattle and goats by about 10 days, and horses by up to 50 days. Actual delivery date depends on the individual animal, litter/calf size, and breed. Use the earliest and latest dates shown as your realistic planning window, not just the single expected date.
Why do horses have such a wide gestation range?
Mares have one of the widest natural gestation ranges of any common domestic species — roughly 320 to 370 days, a 50-day spread. Factors like foal sex, time of year bred, and individual mare variation all play a role, and equine researchers still don't fully understand why the range is this wide compared to other livestock.
Do larger litters change the due date?
Often yes, for litter-bearing species. Dogs, cats, and goats carrying larger litters tend to deliver a few days earlier than average, while single or smaller litters often go a bit longer — likely due to physical space constraints as the litter grows.
What if my animal goes past the latest date shown?
Going past the typical window doesn't automatically mean a problem, but it's a signal to contact your veterinarian, especially if your breeding date estimate might be off or if you notice any signs of distress, decreased activity, or other concerning symptoms.
Is the breeding date the same as the conception date?
Not always. For most species here, breeding and conception happen close together, but cats are induced ovulators — mating itself triggers ovulation, so the gestation clock starts close to the mating date. For species bred via AI or with a known ovulation date, using the ovulation date instead of the mating date gives a more precise estimate.

References & Sources

  1. [1]
    Merck Veterinary Manual - Gestation Lengths (opens in new tab)

    Supports: Veterinary gestation ranges for common domestic animal species.

    Verified

  2. [2]
    MSD Veterinary Manual - Reproduction in Horses (opens in new tab)

    Supports: Veterinary guidance on mare breeding, gestation, and foaling timelines.

    Verified

  3. [3]
    USDA APHIS - Livestock and Poultry Disease (opens in new tab)

    Supports: Official animal-health, disease-control, and veterinary oversight context.

    Verified