Quick answer: Enter the first day of your dog’s last heat into this dog heat cycle calculator, along with how far apart her heats usually are. Most dogs come into heat about every 6 months, with an average of 7. Within each heat, she is usually fertile from about day 10 to day 18 after bleeding starts.
Tip: if you know her usual gap from past heats, pick that instead.
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How does this dog heat cycle calculator work?
The calculator adds her usual gap between heats to the first day of her last one. If you are not sure of the gap, start with 6 months, which suits most dogs. Pick a shorter gap for small breeds and a longer one for giant breeds.
It then marks the two stages of each heat that matter most. The first stage lasts about 9 days, and she will not accept a male. The second stage also lasts about 9 days, and this is when she can get pregnant.
How far apart are her heats?
A typical gap between heats is about 7 months, which is the calculator’s default. Some healthy dogs come back into heat after only 4 months, and others wait more than a year, so pick her own gap if you know it.
- Small breeds may cycle three times a year.
- Giant breeds such as Great Danes may cycle only once every 9 to 12 months.
- Young dogs are often irregular. Their cycles can take up to two years to settle.
For the best prediction, track her heats for a year or two and use her own average.
How many days after bleeding is a dog fertile?
Usually from about day 10 to day 18 after bleeding starts. That is the second stage of heat, called estrus. Her discharge often turns lighter and more watery, and she starts to accept a male.
Ovulation tends to happen when the discharge changes color. That is why this tool also works as a rough dog ovulation calculator, marking her likely fertile days. Because sperm can survive about a week inside her, mating a few days before ovulation can still lead to puppies.
These are averages. Because each stage can last anywhere from 2 days to 3 weeks, some dogs are fertile much earlier or later.
If you are planning a litter, your vet can time ovulation with progesterone blood tests, usually taken every two days. That also makes the due date far more exact in our dog pregnancy calculator. If she has already mated, read how to tell if your dog is pregnant.
How many days will a female dog let a male mount her?
Only during estrus, which lasts about 9 days on average. The range is wide, from 3 days to 3 weeks. Before that, in the first stage, she attracts males but usually turns them away.
How do I know when her heat is over?
Her heat is ending when the discharge stops, her vulva shrinks back toward its normal size and she no longer interests or accepts males. Keep her away from intact males for a few more days, because she can still conceive late in estrus.
How accurate is a heat cycle prediction?
It is a planning guide, not a promise. Heat timing depends on breed, age and the individual dog, and stress or illness can delay a cycle. The fertile days are averages too.
For breeding, a vet’s progesterone and smear tests are the only way to pin down her best days. For everything else about her cycle, read our guide to the dog heat cycle.
Frequently asked questions
How long does a dog’s heat last?
About two to three weeks in total. The bleeding stage and the fertile stage each average about 9 days.
When will my dog go into heat next?
Add her usual gap between heats to the first day of her last one. For most dogs that is about six months. The calculator above does this for you and lists her next three heats.
Can I predict my dog’s first heat?
Only roughly. A small dog often starts around 6 months old, while a large or giant breed may not cycle until 18 months to 2 years. Once she has had one, the calculator can plan the next.
Why did her heat come early or late?
Gaps between heats vary from cycle to cycle, especially in young dogs. A heat that comes a month early or late is common. Very irregular cycles in an adult dog are worth a vet check.
Can a dog get pregnant on the first day of bleeding?
It is unlikely, because she is not yet fertile and usually refuses males. But sperm can live about a week, so mating in late proestrus can still lead to a pregnancy.
Does a tie have to happen for her to get pregnant?
No. A tie is common during mating, but a dog can get pregnant without one.
Do spayed dogs go into heat?
No. A fully spayed dog has no heat cycles. If a spayed dog shows heat signs, see your vet, because some ovary tissue may have been left behind.