Dog Heat Cycle Calculator
Enter the date your dog's heat signs began to see an approximate timeline of the typical estrous cycle stages. Individual cycles vary significantly, so treat these as general ranges, not exact dates.
Last updated: September 23, 2026
Frequently asked questions
What are the stages of a dog's heat cycle?
The canine estrous cycle is commonly described in four stages: proestrus (swelling and bloody discharge begin, not yet receptive to mating), estrus (the fertile window when a female is typically receptive), diestrus (a longer post-heat phase whether or not pregnancy occurred), and anestrus (a resting phase between cycles).
How often do dogs go into heat?
Most dogs cycle roughly every 6 months, but the interval varies widely - anywhere from about 4 to 12 months between cycles is considered within a normal range depending on the individual dog and breed, which is why this calculator lets you adjust the interval field rather than fixing it at 6 months.
Can this calculator tell me exactly when my dog is fertile?
No - it gives a general approximate window based on typical average stage lengths, not a precise fertility determination for your specific dog. If precise timing matters, such as for a planned breeding, a veterinarian can assess the actual cycle stage using vaginal cytology or progesterone testing, which is far more accurate than date estimates alone.
How is this different from the Dog Pregnancy Calculator?
This Dog Heat Cycle Calculator estimates the stages and timeline of the reproductive (estrous) cycle itself, before and around mating. The Dog Pregnancy Calculator instead estimates a due date after a mating has already occurred, working forward from the mating date using the typical canine gestation length - they cover different points in the reproductive timeline.
What are common signs that a dog has entered heat?
Common early signs include vulvar swelling and a bloody or blood-tinged discharge, along with behavioral changes like increased urination frequency and attracting more attention from male dogs - the appearance of these signs is typically what owners use as the starting reference point (proestrus onset) for tracking the cycle.
Does spaying eliminate heat cycles?
Yes - a spayed female dog (with ovaries removed) no longer cycles through heat, since the hormonal cycle depends on the ovaries. This calculator is intended for unspayed female dogs going through their natural reproductive cycle.