How long is a guinea pig pregnant?
A guinea pig sow carries her young about 68 days, with a normal range of 59 to 72 days, according to the Merck Veterinary Manual. That is a long pregnancy for such a small animal, roughly two and a half months.
Due date = mating date + 68 days
Guinea pig breeding at a glance
| Figure (Merck Veterinary Manual) | |
|---|---|
| Gestation | 59 to 72 days, average 68 |
| Litter size | 2 to 4 |
| Breeding age | Females 2 months, males 3 months |
| Weaning | 3 to 5 weeks |
Guinea pig young are born well developed, with fur and open eyes, and they start nibbling solid food within days. That is why the sow nurses for only a few weeks.
Sample due dates
| Bred | Due date | Normal window |
|---|---|---|
| Thu, Jan 1, 2026 | Tue, Mar 10, 2026 | Sun, Mar 1, 2026 to Sat, Mar 14, 2026 |
| Sun, Mar 1, 2026 | Fri, May 8, 2026 | Wed, Apr 29, 2026 to Tue, May 12, 2026 |
| Fri, May 1, 2026 | Wed, Jul 8, 2026 | Mon, Jun 29, 2026 to Sun, Jul 12, 2026 |
| Wed, Jul 1, 2026 | Mon, Sep 7, 2026 | Sat, Aug 29, 2026 to Fri, Sep 11, 2026 |
| Tue, Sep 1, 2026 | Sun, Nov 8, 2026 | Fri, Oct 30, 2026 to Thu, Nov 12, 2026 |
| Sun, Nov 1, 2026 | Fri, Jan 8, 2027 | Wed, Dec 30, 2026 to Tue, Jan 12, 2027 |
The window is the 59 to 72 day range from Merck. Most sows deliver near day 68, and your vet can tell you when to be concerned. To compare other small pets, see the pet rodent gestation chart, or the full animal gestation periods chart.
Frequently asked questions
How long is a guinea pig pregnant?
About 68 days on average, with a normal range of 59 to 72 days, according to the Merck Veterinary Manual.
How many babies do guinea pigs have?
A litter is usually 2 to 4 pups. Guinea pig young are born furred with their eyes open.
At what age can a guinea pig breed?
Merck gives sexual maturity at about 2 months for females and 3 months for males, but talk to your vet about the right age to breed a sow.
When are guinea pig pups weaned?
At about 3 to 5 weeks. They start nibbling solid food within a few days of birth.
Sources
Reference charts
More gestation calculators
Cow Gestation Calculator
Calving date by breed, with the normal window.
Horse Gestation Calculator
Foaling date with the 320 to 370 day window.
Goat Gestation Calculator
Kidding date for dairy, meat and pygmy goats.
Sheep Gestation Calculator
Lambing date for ewes, with the normal window.
Dog Pregnancy Calculator
Whelping date with week-by-week milestones.
Cat Pregnancy Calculator
Kitten due date and stages of cat pregnancy.