An animal gestation calculator adds the species' typical pregnancy length to the breeding date. Dogs average about 63 days (normal 58–72 from breeding), cats about 65, pigs 114, sheep 147, goats 150, cows 283 and horses about 340 days. Pick the animal, enter the breeding date and you get the due date, the normal window and how far along the pregnancy is today.
Every length comes from the Merck Veterinary Manual or a university extension service or veterinary school. It is a planning tool, not a diagnosis: your veterinarian should confirm the pregnancy and help you plan for the birth.
How to use this due date calculator
- Choose the animal: dog, cat, sheep, goat, pig, cow, horse, rabbit, or llama and alpaca.
- For a dog, choose what you are counting from. The breeding date is the default; pick ovulation, LH surge or diestrus if your vet ran tests.
- Enter the date. It defaults to today, which is handy if you are planning a breeding.
- Read the due date, the normal window and the day of pregnancy today. For dogs and cats you also see the next vet checkpoint.
- Press Share to save the result or send it to your vet or breeder.
How the due date is calculated
Due date = start date + typical gestation (days). The window is start date + the low end and + the high end of the normal range. “Day of pregnancy” is the days from the start date to today.
| Animal | Typical length | Normal range | Source |
|---|---|---|---|
| Dog | 63 days | 58–72 days | Merck: 58–72 d from breeding; 62–64 d from ovulation (63 = midpoint) |
| Cat | 65 days | 60–66 days | Merck: ~65 d; pregnancy 60–65 d; birth typically 64–66 d after breeding |
| Sheep (ewe) | 147 days | 144–151 days | Montana State Ext.: breed averages 144–151 d, about 147; individuals 138–159 |
| Goat (doe) | 150 days | 145–155 days | Merck: 145–155 d, average 150 |
| Pig (sow) | 114 days | 110–117 days | Purdue vet school: 114 d; Penn State Ext.: most farrow 110–117 d |
| Cow | 283 days | 279–287 days | UNL Beef: 279–287 d, 283 common |
| Horse (mare) | 340 days | 320–370 days | Merck: about 340 d; eXtension Horses: 320–370 d |
| Rabbit | 31 days | 31–33 days | Merck: ~31–33 d |
| Llama / alpaca | 342 days | 332–352 days | Merck: camelids ~342 ± 10 d; alpacas somewhat shorter |
For dogs, 63 days is the midpoint of Merck's 62–64 days from ovulation. For llamas and alpacas, Merck gives about 342 ± 10 days for camelids and notes alpacas run somewhat shorter, so treat that row as approximate.
Dog due date calculator: why the start date matters
Dogs are the hardest species to predict from a breeding date. The Merck Veterinary Manual explains that a bitch's estrous behavior doesn't line up closely with ovulation, and semen can stay viable in her reproductive tract for 7 days or more. That is why the range from breeding is a wide 58–72 days. Hormone timing narrows it:
| Counting from | Gestation |
|---|---|
| First breeding / mating | 58–72 days |
| Ovulation (progesterone-timed) | 62–64 days |
| LH surge / progesterone rise > 2 ng/mL | 64–66 days |
| First day of diestrus (vaginal cytology) | 56–58 days |
If you plan an elective cesarean, ovulation timing matters: Merck says it can be done safely after 62 days of gestation, but earlier the puppies' lungs may not be ready. Near term, most dogs' rectal temperature drops to about 98.8°F (range 98.1–100°F) 8–24 hours before whelping.
Worked examples
Dog bred on April 10
April 10 + 63 days = June 12, 2026. The normal window runs from June 7, 2026 to June 21, 2026. If a progesterone test put ovulation on April 12, the date becomes June 14, 2026 with a much tighter window of Jun 13 to Jun 15.
Ewe bred on October 15 (lamb gestation)
October 15 + 147 days = March 11, 2027. Breed averages put lambing between Mar 8 and Mar 15. If rams ran with the ewes for several weeks, work out the first and last possible dates and plan for lambing across that whole spread.
Sow bred on June 1 (swine gestation)
June 1 + 114 days = September 23, 2026. Most sows farrow between Sep 19 and Sep 26, so move her to the farrowing area before the early date.
Mare bred on May 20
May 20 + 340 days = April 25, 2027. The normal range is wide, from April 5, 2027 to May 25, 2027, and extension specialists note that many mares follow a similar pattern each year, so her past foaling records are a useful guide.
Dog due date table for 2026
Counted from the first breeding date, 63 days typical.
| Bred on | Due date | Normal window |
|---|---|---|
| Jan 1 | March 5, 2026 | Feb 28 – Mar 14 |
| Feb 1 | April 5, 2026 | Mar 31 – Apr 14 |
| Mar 1 | May 3, 2026 | Apr 28 – May 12 |
| Apr 1 | June 3, 2026 | May 29 – Jun 12 |
| May 1 | July 3, 2026 | Jun 28 – Jul 12 |
| Jun 1 | August 3, 2026 | Jul 29 – Aug 12 |
| Jul 1 | September 2, 2026 | Aug 28 – Sep 11 |
| Aug 1 | October 3, 2026 | Sep 28 – Oct 12 |
| Sep 1 | November 3, 2026 | Oct 29 – Nov 12 |
| Oct 1 | December 3, 2026 | Nov 28 – Dec 12 |
| Nov 1 | January 3, 2027 | Dec 29 – Jan 12 |
| Dec 1 | February 2, 2027 | Jan 28 – Feb 11 |
Sheep gestation calculator table for 2026
Lambing dates for ewes bred on the first of each month, 147 days typical.
| Bred on | Lambing date | Normal window |
|---|---|---|
| Jan 1 | May 28, 2026 | May 25 – Jun 1 |
| Feb 1 | June 28, 2026 | Jun 25 – Jul 2 |
| Mar 1 | July 26, 2026 | Jul 23 – Jul 30 |
| Apr 1 | August 26, 2026 | Aug 23 – Aug 30 |
| May 1 | September 25, 2026 | Sep 22 – Sep 29 |
| Jun 1 | October 26, 2026 | Oct 23 – Oct 30 |
| Jul 1 | November 25, 2026 | Nov 22 – Nov 29 |
| Aug 1 | December 26, 2026 | Dec 23 – Dec 30 |
| Sep 1 | January 26, 2027 | Jan 23 – Jan 30 |
| Oct 1 | February 25, 2027 | Feb 22 – Mar 1 |
| Nov 1 | March 28, 2027 | Mar 25 – Apr 1 |
| Dec 1 | April 27, 2027 | Apr 24 – May 1 |
Pig gestation table for 2026
Farrowing dates for sows bred on the first of each month, 114 days typical.
| Bred on | Farrowing date | Normal window |
|---|---|---|
| Jan 1 | April 25, 2026 | Apr 21 – Apr 28 |
| Feb 1 | May 26, 2026 | May 22 – May 29 |
| Mar 1 | June 23, 2026 | Jun 19 – Jun 26 |
| Apr 1 | July 24, 2026 | Jul 20 – Jul 27 |
| May 1 | August 23, 2026 | Aug 19 – Aug 26 |
| Jun 1 | September 23, 2026 | Sep 19 – Sep 26 |
| Jul 1 | October 23, 2026 | Oct 19 – Oct 26 |
| Aug 1 | November 23, 2026 | Nov 19 – Nov 26 |
| Sep 1 | December 24, 2026 | Dec 20 – Dec 27 |
| Oct 1 | January 23, 2027 | Jan 19 – Jan 26 |
| Nov 1 | February 23, 2027 | Feb 19 – Feb 26 |
| Dec 1 | March 25, 2027 | Mar 21 – Mar 28 |
What affects gestation length
- Breed. Finn and other prolific sheep breeds carry for 144–145 days on average, while Rambouillet carry for 150–151 days (Montana State).
- Litter size. Ewes carrying multiples tend to deliver a little sooner. Rabbits with small litters (usually four or fewer) tend to carry longer (Merck).
- Sex of the offspring. Bull calves and colts tend to be carried a little longer; colts by about 2–7 days.
- Season. Mares due in late spring and summer tend to have shorter pregnancies than mares due in January or February.
Pregnancy checks for dogs and cats
The Merck Veterinary Manual says ultrasound is the most useful way to confirm pregnancy and is best done at 25–35 days; before day 21 it can give a false negative. A blood relaxin test can detect pregnancy in dogs after 22–27 days. Fetal skeletons show on X-ray from about day 42–45, and an X-ray after day 55 is the best way to count the litter so you know when birth is complete.
When to see a vet
This calculator is general information, not veterinary advice. Book a vet visit to confirm any pregnancy and to plan nutrition, vaccinations and the birth. Get help right away if labor stalls: for dogs, Merck lists no puppy within 24 hours of the temperature falling below 100°F, strong contractions for more than 1–2 hours without a birth, a rest of more than 4–6 hours, obvious pain, or abnormal discharge. Call your vet too if the due window passes with no signs of labor, or if you see bleeding, a foul discharge or a sick-looking mother at any stage.
Don't give a pregnant or nursing dog any medicine, including antihistamines, without asking your vet first; see the dog Benadryl dosage calculator for why. To count days forward from any date, use the date from today calculator.
Frequently asked questions
How long is a dog pregnant?
About 63 days, but the Merck Veterinary Manual gives 58–72 days counted from the first day the female accepted breeding. Counted from ovulation the range narrows to 62–64 days, from the LH surge to 64–66 days, and from the first day of diestrus to 56–58 days.
How accurate is a dog due date calculator?
Only as accurate as the date you count from. Merck notes that breeding dates do not predict whelping closely, because sperm can survive in the female's tract for 7 days or more. A date from progesterone or LH testing, or from vaginal cytology showing the start of diestrus, is far more precise.
What is the gestation period for sheep?
About 147 days. Montana State University Extension gives breed averages of 144–151 days, with individual ewes ranging from 138 to 159 days. Prolific and early-maturing meat breeds tend to be shorter (144–145 days) and fine-wool breeds such as Rambouillet longer (150–151 days).
How long are pigs pregnant?
About 114 days, often remembered as 3 months, 3 weeks and 3 days (Purdue University). Penn State Extension says most sows farrow between days 110 and 117. The Merck Veterinary Manual notes modern sows average 115–116 days from first service, slightly shorter with larger litters.
How long is a goat pregnant?
The Merck Veterinary Manual gives 145–155 days, averaging 150. Breed, litter weight, environment and the number of previous pregnancies all affect it.
How long is a cow pregnant?
About 283 days for most breeds. University of Nebraska–Lincoln Beef gives a range of 279–287 days; cows carrying bull calves tend to carry slightly longer than those carrying heifers.
How long is a horse pregnant?
About 340 days, or roughly 11 months (Merck Veterinary Manual). Extension horse specialists give a normal range of 320–370 days. Foals born before 326 days are considered premature and usually need a vet right away.
How long is a cat pregnant?
About 65 days. The Merck Veterinary Manual says pregnancy lasts 60 to 65 days and birth typically occurs 64 to 66 days after breeding. Cats are induced ovulators, so the breeding date is a closer guide than it is in dogs.
How long is a rabbit pregnant?
About 31–33 days, per the Merck Veterinary Manual. Merck advises that if a doe has not kindled by day 32, a veterinarian may induce birth, because a litter delivered after day 34 is almost always dead.
When should I call the vet during whelping?
Merck lists these signs of trouble in dogs: no birth within 24 hours of the temperature dropping below 100°F, strong contractions for more than 1–2 hours with no puppy, a rest of more than 4–6 hours during labor, obvious pain, or abnormal discharge. Call your vet straight away if any apply.
What if my animal goes past the due date?
Being a few days past the typical length is normal as long as you are still inside the normal window. Past the end of the window, contact your vet. The Merck Veterinary Manual describes true prolonged gestation in cattle and sheep as a medical problem that usually needs induction or a cesarean.
Sources & method
- Merck Veterinary Manual — Table: Approximate gestation periods
- Merck Veterinary Manual — Whelping and queening in bitches and queens
- Merck Veterinary Manual — Breeding management of bitches
- Merck Veterinary Manual — Pregnancy determination in bitches and queens
- Merck Veterinary Manual (Dog Owners) — Reproductive disorders of female dogs (dystocia signs)
- Merck Veterinary Manual (Cat Owners) — Management of reproduction of cats
- Montana State University Extension — Sheep reproduction
- Merck Veterinary Manual — Breeding, parturition and common lamb diseases of sheep
- Merck Veterinary Manual — Pregnancy in goats
- Purdue University College of Veterinary Medicine — Your sow is expecting (VA-30-W)
- Penn State Extension — Raising pigs 1: farrowing
- Merck Veterinary Manual — Breeding management of pigs
- University of Nebraska–Lincoln Beef — How long does a cow's pregnancy last?
- Merck Veterinary Manual (Horse Owners) — Management of reproduction in horses
- eXtension Horses (Cooperative Extension) — Management of the pregnant mare
- Merck Veterinary Manual — Management of rabbits
- Merck Veterinary Manual — Reproduction of llamas and alpacas
Results are estimates for general information. Found an error? It helps everyone — see our methodology.