# Dog due date calculator

> Find a dog’s whelping date from ovulation, the LH peak or the breeding date, with the ultrasound, X-ray and temperature milestones from the Merck Veterinary Manual.

Canonical: https://lucernel.com/tools/dog-due-date-calculator
Last updated: 2026-09-26

Choose the date you know: ovulation, the LH peak or the breeding. You get the expected whelping window and the checkups along the way.

Free, no account. Everything runs in your browser. Nothing you type is sent or stored. Interactive version: https://lucernel.com/tools/dog-due-date-calculator

## How it works

Pregnancy in dogs lasts about 62 to 64 days from ovulation, according to the Merck Veterinary Manual. Counted from the LH peak it is 64 to 66 days, and counted from breeding it can be anywhere from 58 to 72 days, because the breeding date does not always match the date of conception.

That is why a date from progesterone or LH testing gives a much tighter window than a breeding date. With two or more matings, the tool uses the first and last dates to widen the window.

The milestones come from the same manual: ultrasound can reliably detect pregnancy from about 25 to 35 days, skeletons show on X-ray from about day 45, and an X-ray after day 55 is the best way to count the puppies.

Formula: Due window = ovulation + 62 to 64 days, LH peak + 64 to 66 days, or breeding + 58 to 72 days.


## Good to know

- Length also varies with breed and litter size. Plan around the window, not a single day.
- A drop in rectal temperature usually comes about 8 to 24 hours before delivery. Call your veterinarian if labor stalls or the dog is in distress.

## Frequently asked questions

### How long are dogs pregnant?

About 62 to 64 days from ovulation. From a breeding date it can range from 58 to 72 days, because the breeding date does not always match the date of conception.

### When can a vet confirm a dog is pregnant?

Ultrasound can reliably detect pregnancy from about 25 to 35 days. An X-ray after about day 55 is the best way to count puppies.

### How do I know labor is close?

A drop in rectal temperature usually comes 8 to 24 hours before delivery. The dog may also become restless, nest, hide or refuse food.

## Littero keeps the whole kennel book.

Heat cycles, progesterone results, matings, litters and puppies for every dog, with reminders for the dates that matter.

- Heat cycles and progesterone charts
- Mating-to-whelping date ranges
- Litters and puppy weigh-ins

[Littero](https://lucernel.com/apps/littero)

## Sources (checked 2026-09-26)

- [Merck Veterinary Manual: Management of reproduction in dogs](https://www.merckvetmanual.com/dog-owners/reproductive-disorders-of-dogs/management-of-reproduction-in-dogs)
- [Merck Veterinary Manual: Approximate gestation periods](https://www.merckvetmanual.com/multimedia/table/approximate-gestation-periods)