Free Breeder Tool
Dog heat cycle calculator
Enter her last heat and usual interval to project the next three cycles, each with an estimated breeding window and, if you breed, a due date range.
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Day one is the first day you noticed bleeding or swelling.
Six months is the average. Small breeds often run 5 to 7 months, giant breeds 8 to 12.
Enter her last heat date above to project her next three cycles.
The Full Version Lives in BreederBuddy
This tool guesses from an average. BreederBuddy learns her.
Every female has her own rhythm. Log each heat in BreederBuddy and it works out her true interval from her own history, then plans forward from real numbers.
Forecasts from her history
BreederBuddy learns each female's average interval and forecasts her next 3 to 4 cycles on a visual timeline beside your other girls, with a progress bar toward the next predicted heat.
Progesterone on the cycle
Log each draw with the date and ng/mL value and watch the rise across tests, so breedings are timed from lab numbers instead of the calendar.
Whelping Watch
Once she's bred, pregnancy-check and due-date reminders generate automatically. Log her temperature near the end and BreederBuddy flags the pre-labor drop and predicts the whelping window.
Heat tracking, the litter planner timeline, and Whelping Watch are all part of daily workflows. See how breeders use them →
More free breeder tools
Puppy Go-Home Date Calculator
Turn a whelp date into a go-home date and week-by-week litter milestones, or work backwards from a target pickup window.
Open tool →Litter Profitability Calculator
See what a litter actually earns after stud fees, vet work, supplies, per-puppy costs, and your own hours.
Open tool →Puppy Pricing Calculator
Work out a puppy price that covers your real costs with room to spare, and stress-test it against a small litter.
Open tool →Breeding Contract Generator
Answer a few questions and get a draft puppy or kitten sales contract covering deposits, vet checks, health guarantees, and more.
Open tool →Puppy Vaccination Schedule
A week-by-week vaccine and deworming schedule for the whole litter, dated from your whelp date and ready to confirm with your vet.
Open tool →Puppy Buyer Questionnaire
Build a buyer screening questionnaire from proven questions about home, experience, lifestyle, and expectations.
Open tool →Puppy Waitlist Template
A free spreadsheet template for tracking waitlist families, deposits, preferences, and litter assignments.
Open tool →FAQs
Common questions about heat cycles
How often do female dogs go into heat?
On average every 6 months, but the normal range runs 4 to 12 months and it is strongly individual. Small breeds may cycle every 5 to 7 months, while giant breeds like Great Danes often run 8 to 12 months between heats. A female's own history is a far better predictor than any breed average.
How long does a dog stay in heat?
A full heat lasts 2 to 4 weeks. The first phase (proestrus) brings swelling and bleeding but no receptivity, typically 7 to 10 days. The fertile phase (estrus) follows, usually days 9 to 14 from the start, though some females ovulate as early as day 8 or as late as day 20.
When is a dog most fertile during her heat?
Ovulation most often happens 10 to 14 days after the first day of heat, and eggs are fertilizable for about 2 to 3 days after maturing. Because the window shifts so much between individual females, serious breeders time breedings with progesterone tests rather than the calendar: a rise past 5 ng/mL signals ovulation.
How accurate is a heat cycle calculator?
It is an estimate built on her last heat and an average interval, good for planning months ahead: travel, stud arrangements, waitlist timing. It is not accurate enough to time a breeding. For that, watch for physical signs and run progesterone tests once she starts.
Can BreederBuddy predict my dog's next heat?
Yes, and with better data than this calculator. BreederBuddy stores every heat you log, learns each female's true average interval, and forecasts her next 3 to 4 cycles on a visual timeline next to your other girls. Progesterone results log right on the cycle, and reminders fire as a predicted heat approaches. See heat tracking →
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