Dog Pregnancy Calculator
Due date, whelping window, and vet checks from mating date.
What it does
Dog pregnancy averages 63 days from ovulation, but mating dates predict loosely because sperm survives days and eggs mature after release. Breeders therefore work with a window from first breeding rather than a single fixed day.
The tool above takes the mating date. It returns the 63 day due date with the 56 to 70 day window and the day 28 ultrasound point beside them.
The default mating of October 1 2026 gives December 3 due, window November 26 to December 10, ultrasound from October 29. Ovulation timed breedings tighten this to 63 plus or minus a day or two.
Lengths follow the Merck Veterinary Manual reproduction chapters with Cornell canine health whelping guidance matching them. Both name 62 to 64 days post ovulation with 58 to 72 days possible from first breeding.
How to use
- Enter the first mating date.
- Read the due date for the 63 day mark.
- Plan around the full window, not the single day.
- Book ultrasound from day 28 and x-ray past day 55.
- Watch temperature and nesting near the window.
Formula
- 63
- Average days from ovulation to birth.
- 56-70
- Breeding date window covering sperm life and timing.
- 28 / 55
- Ultrasound and x-ray timing in days.
All dates compute in UTC so zones never shift a day. Multiple matings widen the real window; ovulation testing with progesterone narrows it best.
Worked example
Example: mated October 1 2026
Mating date 2026-10-01.
- Due: Oct 1 + 63 days = Dec 3 2026.
- Early: Oct 1 + 56 = Nov 26.
- Late: Oct 1 + 70 = Dec 10.
- Ultrasound: Oct 1 + 28 = Oct 29.
- Tool shows Thu Dec 03 2026, window, Oct 29 ultrasound.
Reference table
| Day | Check | Method |
|---|---|---|
| 21 | Palpation possible | Vet exam |
| 28 | Ultrasound reliable | Heartbeat check |
| 45+ | Skeleton on x-ray | Count estimate |
| 55+ | Best litter count | Late x-ray |
| 56-70 | Whelping window | Watch closely |
Limits
- Mating dates predict loosely; ovulation timing predicts well.
- Breed and litter size shift real lengths.
- Single puppy litters often run long.
- Vet imaging beats every calendar estimate.
Common mistakes
- Treating the due date as exact from mating.
- Skipping progesterone timing for planned litters.
- X-raying too early for skeletons or counts.
- Missing the temperature drop before labor.
- Planning travel inside the window.
Try it yourself
Quick checks. Answers sit tucked under each question.
Mated Jan 1: due and window?
Due Mar 5 (63 d), window Feb 26 to Mar 12.
Ultrasound for Mar 10 mating?
Mar 10 + 28 = Apr 7.
Why such a wide window?
Sperm lives days and eggs mature after ovulation, so conception lags mating.
Questions
How long are dogs pregnant?
About 63 days from ovulation; 56 to 70 days from first mating.
When can pregnancy be confirmed?
Ultrasound from day 28, x-ray skeletons past day 45, best counts past day 55.
How do I know labor is near?
Temperature drop plus nesting and restlessness, usually within 24 hours.
Why not exact from mating?
Conception can lag mating by days on both ends of the fertile span.
Single puppy different?
Often longer with weaker labor signals; vet monitoring matters more.
Spay while pregnant?
Discuss timing and risks with your vet promptly; options narrow fast.