📅 Her cycle details

Start date of her most recent heat Start date of the heat before that (optional, but recommended)

💡 Add a second date and we'll calculate her actual personal cycle length instead of a generic breed average — much more accurate for irregular cyclers.

Breed size (used only if you don't provide a second date)

Small

Medium

Large

Giant

Predicted next heat

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0

day of cycle

0

days to next heat

0

cycle length (days)

ProestrusEstrusDiestrusAnestrus

This tool gives a general estimate based on typical canine heat-cycle patterns. Individual dogs vary, especially young dogs whose cycles can be irregular for the first 1–2 years. Always confirm with your veterinarian, particularly before breeding or if her pattern seems unusual.

📖 What each stage means

✅ Heat cycle prep checklist

🩲Have dog diapers or washable belly bands ready for the bleeding phase (proestrus).

🚫Keep her away from unneutered male dogs from proestrus through the end of estrus — she can attract males even before she's fertile.

🐕‍🦺Leash walks only during her fertile window; avoid off-leash dog parks.

🧼Extra cleaning supplies for spotting around the house.

📋Log the start date of this cycle so future predictions get even more accurate.

🏆 Why this calculator is different

📊Learns from her actual cycle history — enter two past heat dates and it calculates her real personal interval, instead of assuming a flat "every 6 months" like most calculators.
🐕Breed-size adjusted default — small breeds often cycle more often, giant breeds less often, used as a smart fallback if you only have one date.
🌡️Shows her current stage (proestrus, estrus, diestrus, anestrus) visually on a timeline, not just a single due date.
⚠️Highlights the fertile window with a clear safety reminder — useful whether you're preventing or planning a pregnancy.
✅Built-in prep checklist for the practical side (diapers, avoiding male dogs, cleaning) that most calculators skip entirely.
🔒No sign-up, no data stored — everything runs in your browser only.

❓ Frequently asked questions

How long is a dog's heat cycle?

The active bleeding and fertile phase (proestrus and estrus combined) typically lasts about 2 to 4 weeks, while the full cycle — until the next heat begins — commonly ranges from 4 to 12 months depending on the dog.

How often do dogs go into heat?

Most dogs cycle roughly every 6 months, but smaller breeds often cycle more frequently (sometimes 3 times a year) and giant breeds may cycle only once a year or even less often.

When is a dog most fertile during her heat?

Fertility typically peaks during the estrus stage, roughly days 9 through 14 of the cycle, though timing can vary — a progesterone test from your vet gives the most accurate breeding window.

🌸 Dog Heat Cycle Calculator