Guinea Pig Pregnancy Calculator by Mark Guinea Pig Pregnancy Calculator Estimate your guinea pig’s delivery date and track pregnancy stages. Mating Date ? Select the date of successful mating (e.g., 2025-04-01). Gestation Period (days) ? Average is 65 days; range is 59–72 days (smaller litters may take longer). Calculate Reset Enter the mating date, then click “Calculate”. JavaScript is disabled. Please enable it to use the calculator. Share this: Click to share on Facebook (Opens in new window) Facebook Click to share on X (Opens in new window) X Like this:Like Loading... Related