CollarDog Ovulation Calculator: Find the Fertile Window
Planning a breeding? Estimate your dog's fertile window and best mating days from the first day of her heat, so you know roughly when she is most likely to conceive.
Dog Ovulation Calculator
Enter the first day of her heat to estimate the fertile window.
How Dog Ovulation Timing Works
A dog's fertile window opens during the estrus phase of her heat. Counting from the first day she started bleeding (proestrus), ovulation usually happens around day 11, within a natural range of about days 9 to 15.
The eggs need roughly two days to mature after ovulation, so the best mating days are typically days 11 to 13. Many breeders mate every other day across this window.
Estimated ovulation ≈ first day of heat + 11 days
Why This Is Only an Estimate
Dogs do not all ovulate on the same day, and some have silent or irregular heats. That is why the result is shown as a window, and why a vet's progesterone test is the only reliable way to time a breeding.
Note the first day of heat
Record the day bleeding first appeared (start of proestrus).
Read the fertile window
See the estimated ovulation day and best breeding days.
Confirm with your vet
Use a progesterone test to pinpoint the real ovulation date.
Frequently Asked Questions
Answers to the most common questions about dog ovulation and breeding timing.
A dog usually ovulates around day 11 of her heat, counting from the first day of proestrus (the start of bleeding), though it can naturally range from about day 9 to day 15. Because this varies from dog to dog, a progesterone test at your vet is the only reliable way to confirm ovulation.
The best breeding days are usually around days 11 to 13 of the heat, a couple of days after ovulation, once the eggs have matured. Many breeders mate every other day across this window to improve the chances of conception.
A calendar estimate is only a rough guide. Individual dogs ovulate on different days, and silent or irregular heats are common. For a real breeding decision, a progesterone test (and sometimes vaginal cytology) at your vet is the only reliable way to pinpoint ovulation.
Yes. Counting from the first day of heat, ovulation usually falls around day 11, and the best breeding days are roughly days 11 to 13. Many breeders mate every other day across that window. This calculator applies that canine breeding chart to your dog's dates, but a progesterone test remains the only reliable confirmation.
Sources & Further Reading
The timing figures on this page reflect published veterinary averages. To go deeper, visit these trusted references: