How to use the dog pregnancy calculator
Step 1 — Choose your date type. Most owners use the mating date. If your vet tracked an LH surge or ovulation, those dates can be more precise.
Step 2 — Enter the date. The calculator applies the standard 58–68-day delivery window (average 63 days from mating).
Step 3 — Select breed size (optional). Small breeds often whelp around day 62; large breeds around day 64.
Step 4 — Review the timeline. See current week, development notes, and labor signs. Confirm any concerns with your veterinarian.
Gestation formulas
- Average due date = mating date + 63 days
- Earliest delivery = mating date + 58 days
- Latest delivery = mating date + 68 days
- LH surge due date = LH date + 65 days
- Ovulation due date = ovulation date + 63 days
Week-by-week dog pregnancy stages
Week 1 (days 1–7) — Fertilization
Fertilization occurs. Sperm meets egg and embryos begin cell division. No visible signs yet. Sperm can survive in the reproductive tract up to 7 days.
Week 2 (days 8–14) — Blastocyst formation
Zygotes divide repeatedly into blastocysts. Still no visible physical changes in the mother.
Week 3 (days 15–21) — Implantation
Blastocysts implant into the uterine wall (around days 18–21). Relaxin hormone production begins. Signs may include lethargy, tender nipples, morning sickness, and appetite changes.
Week 4 (days 22–28) — Heartbeat detectable
Heartbeats detectable via ultrasound. A vet can confirm pregnancy. Organs and facial features begin forming. Morning sickness may peak — feed bland food if vomiting.
Week 5 (days 29–35) — Visible weight gain
Fetuses develop gender organs. Belly starts to round and weight gain becomes noticeable. Increase food intake. Eyes begin forming.
Week 6 (days 36–42) — Nipple changes
Nipples darken and enlarge. Puppies develop skin pigment. Switch to high-quality puppy food and increase intake by about 35–50% above normal.
Week 7 (days 43–49) — Prepare whelping area
Puppy hair begins growing. Abdomen drops lower. Prepare a quiet whelping box, limit strenuous exercise, and keep the mother away from other animals.
Week 8 (days 50–56) — Nesting begins
Mother may start nesting. Colostrum production begins. You may see puppies moving in the belly. A vet X-ray around day 45 can estimate litter size.
Week 9 (days 57–63+) — Final week & labor
Appetite may reduce. Temperature below 99°F (37.2°C) signals labor within 24 hours. Labor signs include panting, shivering, restlessness, and contractions. Contact your vet if no birth by day 68.
Pregnancy signs & labor checklist
Early & mid-pregnancy signs
- Decreased appetite (first few weeks)
- Nipple swelling and darkening
- Weight gain (noticeable from week 5)
- Morning sickness / vomiting (weeks 3–5)
- Lethargy and behavior changes
- Belly enlargement (visible from week 6)
- Nesting behavior (week 8+)
- Temperature drop below 99°F — labor imminent
Labor signs
- Body temperature drops below 99°F — labor within 24 hours
- Restlessness and nesting
- Loss of appetite
- Panting and shivering
- Visible abdominal contractions
- Stage 1 labor lasts 6–12 hours before active delivery
