Rabbit Gestation Calculator
31 days for helpless young — while a smaller guinea pig takes 68 and produces young that can walk.
The formula
due date = mating date + typical gestation for the species
A window, not a date
Every figure here is the middle of a range that veterinary sources quote, and the ranges are genuinely wide. A dog may deliver anywhere from 58 to 68 days after mating; a mare's range runs from 320 to 370. Treating the central figure as a deadline rather than a midpoint is the most common mistake made with these numbers.
Mating is not conception
Sperm survives in the reproductive tract for days in several of these species, so the date of mating and the date of fertilisation can differ appreciably. In dogs the gap can be as much as a week, which is most of the reason the apparent gestation range is so wide. Counting from ovulation, measured properly, narrows it considerably.
Size does not settle it
Gestation length tracks how developed the young are at birth more than how big the mother is. A rabbit delivers helpless young in 31 days; a guinea pig, smaller still, takes 68 and produces young with fur and open eyes that can eat solid food almost immediately. The difference is a strategy, not a scaling law.
Ratios are expectations, not promises
Every genetic ratio on these pages is a probability distribution, not a guarantee. A 3:1 cross does not produce three dominant offspring for every recessive one in a litter of four — it produces each offspring independently with a three-quarters chance. Small families depart from the expected ratio routinely, and that is the reason Mendel needed thousands of pea plants rather than dozens.