Guinea Pig Gestation Calculator
This guinea pig gestation calculator finds the expected due date instantly. Enter the breeding date to calculate the gestation period for your sow, view key milestones, and plan for the litter's arrival. Covers all common guinea pig breeds.
Quick Answer
Guinea Pig gestation is 65 days — approximately 9.3 weeks or 2.1 months. Larger litters tend to be born earlier in the range. Enter your sow's breeding date in the calculator to calculate the exact expected due date and key milestones.
Guinea Pig Gestation Calculator
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How to Use This Calculator
Enter the date your sow was bred using the date picker. Select the breed from the dropdown for a slightly more precise estimate — Peruvian and Silkie sows tend to carry a few days longer than American or Teddy sows. Click Calculate Due Date to see the expected due date, earliest and latest dates in the normal range, and a full milestone timeline.
Because guinea pig pregnancy carries real risk for sows bred after 6–7 months of age, confirm the breeding date as precisely as you can and monitor closely from day 59 onward. Results are saved in your browser between visits.
How Long Is a Guinea Pig Pregnant?
The gestation period for a guinea pig averages 65 days — approximately 9.3 weeks. This is unusually long for a small rodent: guinea pig pups are precocial, born fully furred, eyes open, with teeth, and able to walk and eat solid food within hours of birth. That advanced development requires more time in the womb than altricial species like mice or hamsters, whose pups are born blind and hairless.
Early pregnancy (days 1–25): Embryo implantation occurs around day 14. There are no outward signs of pregnancy during this window. A veterinarian can sometimes detect a heartbeat by ultrasound around day 20. Avoid unnecessary handling or stress during this critical period.
Mid-pregnancy (days 25–45): Pups develop fur and grow steadily. The sow's appetite increases and her weight climbs noticeably. This is a good time to gradually increase her intake of vitamin C-rich vegetables, since guinea pigs cannot synthesize their own vitamin C and pregnant sows need more of it.
Late pregnancy (days 45–65): The abdomen becomes visibly wide and pear-shaped. The pelvic bones on either side of the spine widen and become easy to feel — a normal and necessary preparation for delivery. Labor is typically quick, often completing within 30 minutes to a few hours, and pups are up and moving almost immediately after birth.
Signs Your Guinea Pig Is Pregnant
Gentle abdominal palpation by an experienced handler or vet, and weight tracking, are the most reliable ways to confirm guinea pig pregnancy early. Beyond that, the following signs help track a sow through the different stages of gestation.
Early signs (weeks 1–3): the sow stops cycling into heat (guinea pigs cycle roughly every 16 days when not pregnant), and steady weight gain begins — often the first objective clue, since a healthy pregnant sow gains weight consistently week over week.
Mid-pregnancy (weeks 4–7): the abdomen visibly widens and takes on a rounded, barrel-like shape. Weight gain accelerates, and by day 35–40 an experienced handler can often feel firm lumps (the pups) through gentle palpation.
Pre-birth signs (final 1–2 weeks): the sow's pelvic bones on either side of the spine widen and become easy to feel — a necessary preparation for delivery vets specifically check for — her abdomen becomes pear-shaped, and she may become restless or seek out a quiet corner in the final day or two before labor.
Guinea Pig Gestation Period in Days, Weeks and Months
The table below converts the guinea pig gestation period into days, weeks, and months for easy reference.
| Measurement | Average | Normal Range |
|---|---|---|
| Days | 65 days | 59–72 days |
| Weeks | 9.3 weeks | 8.4–10.3 weeks |
| Months | 2.1 months | 1.9–2.4 months |
Gestation Period by Guinea Pig Breed
| Breed | Avg. Gestation (Days) | Notes |
|---|---|---|
| American | 65 days | Most common short-haired breed |
| Abyssinian | 65 days | Rosetted coat; average gestation |
| Peruvian | 68 days | Long-haired; tends toward longer end |
| Silkie (Sheltie) | 68 days | Long-haired; tends toward longer end |
| Teddy | 64 days | Dense, wiry coat; slightly shorter |
| Skinny Pig (hairless) | 63 days | Hairless breed; shortest average |
| Coronet | 67 days | Rosetted coat; average gestation |
How Guinea Pigs Compare to Other Small Pets
At 65 days, guinea pigs have one of the longest gestation periods of any small rodent — far longer than a hamster despite being a similarly-sized animal. The table below compares guinea pig gestation to other common small pets.
| Animal | Avg. Gestation (Days) | Vs. Guinea Pig |
|---|---|---|
| Rabbit | 31 days | 34 days shorter |
| Ferret | 42 days | 23 days shorter |
| Cat | 65 days | 0 days shorter |
| Guinea Pig | 65 days | — |
| Dog | 63 days | 2 days shorter |
| Mice | 20 days | 45 days shorter |
| Hamster | 16 days | 49 days shorter |
How We Calculate Guinea Pig Gestation
The guinea pig gestation calculator uses the formula: Due Date = Breeding Date + 65 days. The 65-day average is derived from published small-animal veterinary research and validated by the Merck Veterinary Manual. Because litter size significantly affects gestation length in guinea pigs, the calculator shows the full 59–72 day range so you can plan for early or late delivery.
Frequently Asked Questions
What is the gestation period for a guinea pig?
The gestation period for a guinea pig averages 65 days (about 9 weeks), with a normal range of 59–72 days depending on litter size and breed. Larger litters tend to be born earlier in the range, while smaller litters (1–2 pups) often go closer to day 70–72.
How long are guinea pigs pregnant?
A guinea pig (sow) is pregnant for approximately 59 to 72 days, averaging 65 days. This is unusually long for a rodent — guinea pig pups are precocial, meaning they're born fully furred with their eyes open and are mobile within hours of birth, which requires more in-utero development time than altricial rodents like mice or hamsters.
What is the guinea pig gestation period in weeks?
The guinea pig gestation period is approximately 9.3 weeks on average, with a normal range of 8.4–10.3 weeks (59–72 days). Use the calculator above to enter your sow's exact breeding date and get the precise expected due date by week.
How many pups do guinea pigs have per litter?
Litter size ranges from 1 to 6 pups, with 2–4 being most common. First-time mothers typically have smaller litters. Larger litters place more strain on the sow and are associated with shorter gestation and lower individual birth weights — pregnancy toxemia risk also increases with litter size.
What are signs a guinea pig is about to give birth?
In the final days, a pregnant sow's abdomen becomes very wide and pear-shaped, her hip bones (pelvic bones on either side of the spine) widen noticeably and become easy to feel — a key indicator vets use to assess birthing readiness — and she may become restless or seek out a quiet corner. Labor itself is typically quick, often complete within 30 minutes to a few hours.
Why is guinea pig pregnancy considered risky?
Guinea pig pregnancy carries real risk, especially in sows bred for the first time after 6–7 months of age. After this age, the pelvic bones fuse and can no longer widen enough for a natural delivery, often requiring an emergency C-section. This is why breeders recommend first breeding a sow between 4 and 6 months old, while the pelvis is still flexible.
How does guinea pig gestation compare to other small pets?
At 65 days, guinea pig gestation is far longer than hamsters (16 days) or mice (20 days), and even longer than rabbits (31 days) or cats (65 days, essentially tied) — despite guinea pigs being similar in size to hamsters. The long gestation reflects how developed guinea pig pups are at birth compared to the blind, hairless pups of most other small rodents.
Sources & References
- Merck Veterinary Manual — Guinea pig (cavy) reproduction
- USDA National Agricultural Library — Companion animal care and welfare resources
- Cornell University College of Veterinary Medicine — Small mammal reproduction
- Penn State Extension — Small animal husbandry reference
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Kanika
Researched and reviewed by Kanika, founder of GestationCalc. All gestation data is verified against primary veterinary and agricultural sources before publication.
Last reviewed: September 8, 2026