Kintailthe story of your best friendDog heat cycle calculator
Enter the day your dog's last season began and we'll estimate when her next heat is due — and the fertile window within it. Estimates only; every dog is different.
Enter a valid start date (YYYY-MM-DD) to see the estimate.
How the dog heat cycle works
An intact female dog's reproductive cycle moves through four phases. The day ranges below are typical estimates measured from the first day of proestrus — individual dogs vary widely.
Swelling and a bloody discharge begin. She's attracting males but not yet receptive.
The fertile, receptive window. Ovulation usually falls around days 11–14.
Signs settle down whether or not she's pregnant.
Anestrus
~70 days until the next heat
The quiet resting phase between cycles.
How often do dogs go into heat?
Most dogs cycle about every six months — roughly 180 days — but this varies a lot by size and breed. Smaller dogs often cycle more frequently, while some large and giant breeds only come into season once a year. If you've tracked her before, entering her own cycle length above gives a closer estimate than the average.
Frequently asked questions
How often do dogs go into heat?
Most dogs come into season roughly every six months (about 180 days). Smaller breeds can cycle more often, and large or giant breeds sometimes only once a year — so use your dog's own interval if you know it.
How long does a dog's heat last?
The visible heat — proestrus plus estrus — usually runs about two to three weeks, with the fertile window falling roughly in the middle.
When is a dog most fertile?
Usually during estrus, around days 9–17 after heat begins, with ovulation often near days 11–14. This calculator highlights that estimated window.
Can I use this to plan or avoid breeding?
Treat it as a rough guide only. For breeding or to confirm timing, your vet can run progesterone tests, which are far more accurate than calendar estimates.
Keep the whole story
Kintail turns your daily check-ins into your dog's story — milestones, moods, heat cycles and growth, all in one warm timeline you own.
Track this for your dog →
These figures are population-typical estimates, not veterinary advice — every dog is different. For health concerns, talk to your vet.