Female dogs are typically in heat for about two to three weeks and go into heat roughly every six months, or twice a year, though this varies a lot by breed and individual. Our dog heat cycle calculator takes the first day of bleeding and estimates the fertile window, likely ovulation, when your dog should be out of heat, and when her next cycle is due. The most fertile days usually fall around days 9–15 of the cycle, with ovulation near days 11–13 (VCA Animal Hospitals).
How the dog heat cycle calculator works
The calculator counts forward from day 0 — the first day you notice bleeding or spotting, which marks the start of proestrus. It applies average canine stage lengths: proestrus averages about nine days, followed by estrus (standing heat), the only phase in which your dog can conceive. Ovulation and peak receptivity generally occur around the eleventh day of estrus, so the tool centers the fertile window on days 9–15 and flags likely ovulation near days 11–13 (Cornell Riney Canine Health Center). The next-heat estimate simply projects forward by the interval you choose. These are averages: ovulation can occur as early as day 3–4 or as late as day 18, which is why breeders confirm timing with progesterone testing rather than the calendar alone (AKC).
How long is a dog’s heat cycle, and how long are dogs in heat?
The full estrous cycle has four phases — proestrus, estrus, diestrus and anestrus — and spans roughly six to seven months from one heat to the next. The visible “heat,” when your dog bleeds and attracts males, is the proestrus and estrus phases combined, and lasts about two to four weeks, averaging around three weeks (UC Davis Veterinary Medicine). Proestrus averages about nine days (commonly 7–10), and estrus averages about nine days (commonly 5–10). Diestrus, whether or not she’s pregnant, runs about 60 days, and the resting anestrus phase lasts roughly four to five months before the cycle starts again (Veterinary Partner).
How often a dog goes into heat depends mostly on size. Most dogs cycle about every six months, but the normal interval ranges from four to twelve months. Many small breeds cycle more often — roughly every four months — while giant breeds and the Basenji may only come into season once a year (VCA Animal Hospitals).
Dog heat cycle chart by breed size
Use this heat cycle chart as a general guide. Individual dogs vary, and a breeder who knows your dog’s line is often the best predictor of her pattern.
| Size / example breeds | First heat | Cycles per year | Typical interval |
|---|---|---|---|
| Toy & small — Yorkie, Chihuahua, Shih Tzu, French Bulldog | ~6–7 months | ~2–3 | ~4–6 months |
| Medium — Corgi, Border Collie | ~7–9 months | ~2 | ~6 months |
| Large — Golden Retriever, German Shepherd | ~12–16 months | ~1–2 | ~6–12 months |
| Giant breeds & Basenji | ~12–24 months | ~1 | ~12 months |
Within any single heat, the stages fall in a predictable order: proestrus (bleeding, swollen vulva, not yet fertile), estrus (lighter discharge, standing heat, ovulation and the fertile window), then diestrus and the long anestrus rest. Female dog heat cycle stages don’t change with breed — only their timing and how obvious the signs are do.
How to use the calculator
- Enter the first day of this heat — the first day you noticed spotting or bleeding.
- Choose how often she cycles (about every six months is typical; pick every four months for many small breeds, or once a year for giant breeds).
- Read your results: the estimated fertile window, likely ovulation date, when she’ll likely be out of heat, and her next heat.
- Use the Print / save button to keep a copy, and log every cycle — patterns repeat, so your own records become the most accurate predictor.
BarnCalc · Dogs
Dog Heat Cycle Calculator
Enter the first day of your dog's heat to estimate her fertile window, when she'll likely be out of heat, and when the next cycle is due.
Estimated fertile window
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Enter a start date above.
Your dog's estimated cycle dates
Heat cycle reference chart — by breed size & by stage
| Dog size | First heat | Cycles / year |
|---|---|---|
| Toy & small (Yorkie, Chihuahua, Shih Tzu, Frenchie) | ~6–7 months | ~2–3 |
| Medium (Corgi, Border Collie) | ~7–9 months | ~2 |
| Large (Golden Retriever, German Shepherd) | ~12–16 months | ~1–2 |
| Giant breeds & Basenji | ~12–24 months | ~1 |
| Stage | Typical length | Fertile? |
|---|---|---|
| Proestrus (bleeding starts) | ~9 days (7–10) | No |
| Estrus (standing heat) | ~9 days (5–10) | Yes — ovulation here |
| Diestrus | ~60 days | No |
| Anestrus (resting) | ~4–5 months | No |
Frequently asked questions
How long does a dog stay in heat?
Most dogs are in heat for about two to three weeks, though anywhere from two to four weeks is normal. That visible heat is proestrus (~9 days) plus estrus (~9 days) combined (AKC).
How often do dogs go into heat?
About twice a year for most dogs — roughly every six months — with a normal range of four to twelve months. Small breeds tend to cycle more frequently; giant breeds and Basenjis often only once a year (VCA).
When is a dog most fertile?
The fertile window generally falls around days 9–15 of the cycle, with ovulation and peak receptivity near days 11–13. Because ovulation can shift earlier or later, progesterone testing is the only reliable way to pinpoint it for breeding (AKC).
When do female dogs stop going into heat?
They don’t — dogs do not go through menopause. An intact female keeps cycling for life, though as she ages her heats often become less frequent, less intense, or “silent.” A senior dog can still get pregnant, so a heat that fully stops warrants a vet check (PetMD).
How long after giving birth do dogs go back into heat?
Having a litter doesn’t shorten the resting phase; most dogs return to heat on their usual interval, commonly around six months after the previous cycle. The interval is set by the anestrus phase, which a pregnancy doesn’t measurably change (Veterinary Partner).
Does a spayed dog still go into heat?
No. A standard spay removes the ovaries, so a spayed dog no longer cycles, bleeds, or can become pregnant. Ongoing heat signs after spaying are unusual and should be examined by a vet (PetMD).
Sources
- VCA Animal Hospitals — Estrus and Mating in Dogs: vcahospitals.com
- Cornell University Riney Canine Health Center — Dog Estrous Cycles: vet.cornell.edu
- UC Davis School of Veterinary Medicine — Breeding Management of the Bitch: vetmed.ucdavis.edu
- Veterinary Partner (VIN) — The Canine Estrous Cycle: Being in Heat: veterinarypartner.vin.com
- American Kennel Club — Ovulation Timing / How Long Are Dogs in Heat: akc.org
- PetMD — Dog in Heat: petmd.com
Reviewed for accuracy against VCA Animal Hospitals, Cornell Riney Canine Health Center, UC Davis Veterinary Medicine, Veterinary Partner (VIN) and the AKC.
Last updated: July 16, 2026.
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