Gestation & Due Date Calculator
Enter a plug or mating date and instantly get the expected birth window, weaning date, and the date to separate pups by sex.
Try Moustra freeHow to use the gestation calculator
- Select your species — mouse, rat, hamster, gerbil, guinea pig, or rabbit. Each carries its own typical gestation and weaning age.
- Enter the plug or mating date — the morning you observed a copulation plug is embryonic day 0.5.
- Read the timeline — the expected birth window, weaning date, and the date to separate pups by sex update instantly.
Typical gestation and weaning by species
| Species | Gestation (days) | Weaning (days) |
|---|---|---|
| Mouse | 19–21 (≈20) | 21 |
| Rat | 21–23 (≈22) | 21 |
| Hamster (Syrian) | 15–18 (≈16) | 21 |
| Gerbil | 24–26 (≈25) | 24 |
| Guinea pig | 59–72 (≈65) | 21 |
| Rabbit | 28–33 (≈31) | 35 |
Frequently Asked Questions
How long is a mouse pregnant?
Mouse gestation is typically 19–21 days, most often about 19–20 days. From an observed copulation plug (embryonic day 0.5), you can expect pups roughly three weeks later. Rats are slightly longer at 21–23 days.
What is a copulation plug and when is E0.5?
A copulation (vaginal) plug is a gelatinous mass that forms after mating. By convention, the morning a plug is observed is embryonic day 0.5 (E0.5). Entering the plug date here sets day 0 for the gestation countdown.
When should mouse pups be weaned?
Mouse pups are usually weaned at 21 days of age (commonly 18–28 days depending on the strain and litter). This calculator adds the species' typical weaning age to the expected birth date so you have the date on your calendar.
When do I need to separate pups by sex?
To avoid unplanned litters, separate pups by sex before they reach sexual maturity — around 5–6 weeks (≈42 days) for mice. The 'separate by sex' date is an estimate based on typical puberty age; check your strain.
Is this gestation calculator accurate for my strain?
It uses typical published ranges for each species. Individual strains and conditions vary by a day or two, so treat the birth window as a planning estimate rather than a guarantee. For automated, per-cage tracking of plug dates and due dates, use Moustra.
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