Estimate the current stage of a female dog's heat cycle and when the next heat is likely, from the last start date.
| Days to next heat | – |
| Next heat date | – |
| Stage | – |
Use this calculator as a calendar aid for a female dog. Cycles vary widely by breed and individual; this is not reproduction or breeding advice.
From the day proestrus started, the simplified stages are: proestrus about days 0–9, estrus days 9–18, diestrus days 18–78, then anestrus until the next heat. Enter a typical cycle length in days (180 days, about six months, is a common default). Days to the next heat and the next date are counted from today. If today falls on a heat-start day, days to next heat is 0 and the next date is today.
Last heat start: The day the last heat (bloody discharge / proestrus) started.
Typical cycle (days): How long her cycle usually runs, in days. Many bitches sit around 5–8 months; 180 is a midpoint.
Days to next heat: Whole days from today until the next expected heat start.
Next heat date: The calendar date of that next start.
Stage: The simplified stage for today: proestrus, estrus, diestrus, or anestrus.
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