Dog Heat Cycle Calculator
Estimate where your unspayed female dog is in her heat cycle and when her next heat is likely to begin.
How the canine heat cycle works
Unspayed female dogs typically cycle about twice a year, though this varies by breed and individual, ranging from every 4 months to just once a year. Each cycle has four phases: proestrus (roughly 9 days, bleeding begins), estrus (roughly 9 days, the fertile window), diestrus (about 60 days if not pregnant), and anestrus (a resting phase until the next proestrus begins).
How this calculator works
Enter how many days have passed since her last heat started and her typical cycle length. The calculator estimates which phase she’s likely in and how many days remain until her next heat is expected to begin.
Individual dogs vary, and irregular cycles can indicate a health issue. This tool is for general planning purposes and does not replace a veterinarian’s assessment.