Pets · Dogs

Dog Heat Cycle Calculator

Predict when your female dog will come into heat next, map the four cycle stages to a calendar, and know exactly when she is fertile.

Last heat started

Breed size

Estimated next heat

plus a possible range of a few weeks—

Current stage

—

Days since heat

—

Days to next heat

—

Interval

—

typical for this size

Cycle structure

Proestrus → Estrus → Diestrus → Anestrus → repeat

Proestrus (9 days) brings swelling and bleeding; estrus (9 days) is the fertile window with ovulation around days 2–4; diestrus (about 60 days) follows whether or not she is pregnant; anestrus is the quiet months until the next cycle. Cycles average 180 days but healthy dogs range from 120 to 360.

📅 Next-heat prediction

Estimate the season start from your dog’s breed-size interval.

📈 Stage timeline

Each of the four phases mapped onto real dates, with the fertile window highlighted.

🐜 Live tracking

Tells you which stage she is in today and how far through the cycle you are.

💪 Breed-size aware

Small dogs cycle faster, giant breeds slower — the model adjusts.

Puppies on the horizon?

Match the fertile window with a whelping countdown.

Canine Pregnancy