Dog Heat Cycle Calculator
Plan the next heat & explore the canine estrous cycle.
Editable interval examples — your dog’s recorded cycles are the best starting point.
Heat Cycle Inputs
Next Heat & Cycle Overview
Calendar estimatePlanning window: Dec 23, 2026 – Jan 12, 2027
Canine Estrous Cycle
Illustrative phase lengths. The marker shows elapsed time; the current biological phase has not been confirmed.
Cycle lengths and phase timing vary. Veterinary examination, hormone testing or vaginal cytology may be needed for reproductive decisions.
How the Estimate Works
Jul 06, 2026 + 180 days = Jan 02, 2027
Days remaining = estimated date − reference date
Jan 02, 2027 − Oct 14, 2026 = 80 days
Calendar progress = 100 ÷ 180 × 100 = 55.6%
Frequently Asked Questions
Will the next heat start on this exact date?
No. This is a planning estimate based on your entered interval.
Can the calendar identify ovulation?
No. Individual clinical assessment is needed.
Which interval should I enter?
Use the average of your dog’s recorded heat-start intervals.
What if the predicted date has passed?
Review the history and consult your veterinary team if concerned.
More cycle questions
Are breed presets exact rules?
No. They are editable planning examples, not breed-specific diagnoses. Individual recorded cycle history is more useful.
What does the planning margin mean?
It is a user-selected calendar buffer. It is not a validated biological range or statistical confidence interval.
Does the wheel confirm my dog is in anestrus?
No. It illustrates average phase lengths on the entered interval. The marker records elapsed time only.
Is day 10 always the best mating day?
No. Phase duration and ovulation timing vary. Calendar dates do not establish a fertile window.
Does the calculator detect pregnancy?
No. A cycle estimate cannot diagnose pregnancy.
Can I use this for a spayed dog?
This planning tool is intended for intact females with observed heat cycles. Heat-like signs after spaying need veterinary assessment.
How are dates counted?
The start date is elapsed day zero. Dates are calculated as calendar days, independent of daylight-saving clock changes.
Does an overdue date start a new cycle automatically?
No. A missed estimate is shown as past due; a new observed heat date must be entered. Calendar progress is not reset automatically.
Sources & References
Merck Veterinary ManualCanine cycles & reproductive management
AKC Canine Health FoundationOvulation timing · veterinary educationEducational references · no institutional endorsement.
Estimate the next heat-start date from recorded cycle history, with a planning window and illustrative estrous-cycle timeline.