Dogs • pregnancyVerified Scientific Formula
Dog Heat Cycle & Estrus Timeline Calculator
Tracks canine estrous cycle phases and identifies the peak fertile breeding window and projected timeline for subsequent reproductive cycles.
Enter Parameters
Calculated Output
Current Heat Cycle Stage
Estrus (Standing Heat / Peak Fertility)VERY HIGH (Optimal Mating Window) Fertility Status
What This Result Means
On Day 11 of heat, your dog is in Estrus (Standing Heat / Peak Fertility) (VERY HIGH (Optimal Mating Window)). Discharge turns pink/straw-colored. Female allows mounting and flags tail. Ovulation occurs around Days 11–13.
Calculation Details & Practical Equivalents
Current Cycle Stage
Estrus (Standing Heat / Peak Fertility)
Fertility Assessment
VERY HIGH (Optimal Mating Window)
Peak Fertile Window
Days 10 to 14 from onset
Next Estimated Heat Cycle
~6 months from onset
Formula & Mathematical Methodology
Standard Mathematical Formula
Canine Estrous Cycle: Proestrus (Days 1–9), Estrus / Fertile Window (Days 10–15), Diestrus (Days 16–75), Anestrus (~4–6 months)
Formula Variables Defined
DayDays Since First Bleeding(days)
Elapsed days since onset of serosanguinous discharge
Step-by-Step Calculation Example
Example: Day 11 of Canine Heat
A female dog on Day 11 since initial bloody discharge.
- Days 1–9: Proestrus (vulvar swelling, male attraction without acceptance)
- Days 10–14: Estrus (receptive to mating, LH surge + ovulation)
- Days 15+: Diestrus transition
Final Output: Estrus Stage — PEAK FERTILITY WINDOW (Days 10–14)
Key Assumptions
- Standard canine reproductive physiology applies.
Biological Limitations
Verified Scientific & Veterinary Sources
Version: 1.0•Methodology Reviewed: 2026-01-20
1. The Merck Veterinary Manual (11th Edition)textbook
Aiello, S.E. and Moses, M.A. (Eds.) (2020). Merck & Co., Inc., Kenilworth, NJ
Access Source Authority Dog Heat Cycle & Estrus Timeline Calculator — FAQs
A female dog typically stays in active heat for 2 to 4 weeks (average 21 days), with peak fertility occurring between Days 10 and 14.