Dog Pregnancy Calculator

By the PupGauge editorial team · Last reviewed October 2026 · Method from the Merck Veterinary Manual, Concannon’s canine pregnancy timeline and AKC guidance (sources below). General information, not veterinary advice.

What this calculator helps you plan

Knowing roughly when puppies are due lets you book the right vet checks, set up a whelping area in time, arrange to be home and know when to start watching for labour. Most online “due date” tools add 63 days to a mating date and print a single day. That looks precise, but a single date from a mating is a guess: the real arrival can be a week either side.

This calculator gives you a window, a most-likely date inside it, and the dates when pregnancy checks make sense. It also lets you start from more precise reference points if your vet has run hormone tests, which shrinks the window from about two weeks to about three days.

Which date should you use?

• First mating date — the most common choice. If she was mated more than once, enter the first date and add the last mating date in the optional field.
• LH surge or progesterone rise — if your vet tracked the cycle with blood tests, they can tell you the day luteinizing hormone peaked or progesterone first rose above about 2 ng/mL. This is the most accurate reference.
• Ovulation date — usually about two days after the LH surge, also from vet testing.
• First day of diestrus — identified from vaginal smears (cytology) when the cells change at the end of the fertile period.

Enter the date and press Calculate. The result shows the most likely day, the full normal window, how many days she is into the pregnancy today and a table of check-up dates.

The method and why we chose it

Why mating dates are imprecise

A female dog’s eggs are released immature and need about two to three days to become fertilisable, and sperm can survive in her reproductive tract for several days. A mating can therefore happen well before or after the moment of fertilisation. Reproductive physiologist Patrick Concannon summarised the consequence: from the LH surge, gestation is remarkably consistent at 65 ± 1 days, but from a breeding date it ranges from about 55 to 70 days.

The windows we use

Sources differ slightly for mating dates: Merck’s current veterinary manual gives 58–72 days from the first breeding, while Concannon’s earlier review gave 55–70. We use Merck’s range because it is the more recent clinical reference. The AKC describes typical pregnancies as 62–64 days, which sits in the middle of both.

Check-up dates

For a mating date we follow the American Kennel Club’s guidance: ultrasound 25–35 days after mating, a relaxin blood test from about 25–30 days, palpation by a vet around 28–30 days and an x-ray to count puppies from about day 55. For hormone-based dates we count from the LH surge using Concannon’s timeline: heartbeats visible by ultrasound from about day 25–30, relaxin detectable from about day 24–28 and skeletons visible on x-ray from day 45–47 (we show the counting x-ray from day 55, when skulls, spines and pelvises are clear).

Worked examples

1. A single mating on 1 September 2026

Most likely: 3 November (day 63). Normal window: 29 October to 12 November (days 58–72). Ultrasound: 26 September to 6 October. Relaxin test: 26 September to 1 October. X-ray to count puppies: from 26 October. Start twice-daily temperature checks from 26 October, a few days before the window opens.

2. The same dog, with an LH surge on 1 September from vet testing

Most likely: 5 November (day 65), window 4 to 6 November. The two-week uncertainty shrinks to three days, which is why breeders planning a caesarean or travelling to a vet often use hormone testing.

3. Ovulation dated to 1 September

Ovulation is about two days after the LH surge, so the calculator places the surge on 30 August. Window: 2 to 4 November, most likely 3 November.

4. First day of diestrus on 1 September

Window: 27 to 29 October, most likely 28 October. Diestrus begins about eight days after the LH surge, so the countdown is shorter.

Signs that labour is close

• Temperature drop. In most dogs rectal temperature falls to about 99 °F (37.2 °C) or lower 8–24 hours before labour; Merck reports a mean of 37.1 °C. Take it at the same times morning and evening from a few days before the window opens so you know her normal.
• Nesting and restlessness — digging at bedding, pacing, panting, hiding.
• Loss of appetite in the last day.
• Shivering or vomiting in early labour, which can last several hours before visible straining.

When to call the vet

Agree a plan with your vet before the due window. The AKC advises calling if:

• she has strong contractions for 2 hours without delivering the first puppy;
• more than 2 hours pass between puppies;
• her temperature dropped more than 24 hours ago and labour has not started.

Call immediately for green or black discharge before any puppy arrives, heavy bleeding, collapse or distress. The AKC also suggests calling if no puppies have arrived 64 days after the last mating; the Merck range runs to 72 days from the first. This is a good example of why your own vet’s advice for your dog should set the deadline.

Common mistakes

• Trusting a single due date. Planning for one day leaves you unprepared if she whelps a week early.
• Counting from the last mating. The ranges here are measured from the first breeding.
• Booking the ultrasound too early. Before about day 25 a scan can miss a real pregnancy.
• Feeding for two too soon. Energy needs rise mainly in the last three weeks of pregnancy and peak while nursing; follow your vet’s advice on diet.
• Using the calculator as proof of pregnancy. Only a vet exam, ultrasound, hormone test or x-ray confirms it. False (pseudo-) pregnancy is common in dogs.

Limitations

The windows describe normal pregnancies in healthy dogs. Litter size, breed and individual variation shift timing a little; very small and very large litters can arrive at the edges of the range. The calculator does not detect complications, and it cannot confirm that a mating led to pregnancy. For dogs with a history of difficult births, brachycephalic breeds and planned caesareans, timing should be based on your vet’s hormone testing.

Pregnancy week by week

Counting from a mating date (approximate) and from the LH surge (more precise):

• Weeks 1–3. Fertilisation and early embryo development; embryos implant in the uterus around the third week. Few outward signs, though some dogs are quieter or slightly off their food.
• Week 4. Ultrasound can usually show heartbeats; a vet may feel small swellings in the uterus around days 28–30. This is the best window to confirm pregnancy.
• Weeks 5–6. The belly begins to round, nipples darken and enlarge, and appetite rises. Fluid around the puppies makes them harder to feel by hand.
• Weeks 7–8. Skeletons mineralise and become visible on x-ray. Puppies may be felt moving. Prepare the whelping box in a quiet, warm room and let her get used to it.
• Week 9. Milk may appear, she may nest, and her temperature will drop before labour. Have your vet’s number and an emergency clinic ready.

What to prepare before the window opens

• A whelping box with low sides she can step over and a rail to stop puppies being squashed against the walls.
• Clean towels, a digital thermometer, a kitchen scale for weighing newborns, a notebook for birth times and weights, and unwaxed dental floss and clean scissors in case your vet advises tying a cord.
• A warm, draught-free room; newborn puppies cannot regulate their own temperature for the first weeks.
• A plan for after-hours veterinary help, agreed with your vet in advance.

Frequently asked questions

How long are dogs pregnant?

About 63 days on average. From a mating date the normal range is roughly 58–72 days; from the LH surge it is 64–66 days.

How accurate is a dog due date calculator?

From a single mating date, expect a window of about two weeks. With vet hormone testing (LH surge or progesterone), it narrows to about three days.

When can I confirm my dog is pregnant?

By ultrasound from about 25–35 days after mating, a relaxin blood test from about 25–30 days, and x-ray from about day 55, which also counts the puppies.

My dog was mated several times. Which date do I use?

Enter the first mating date; the window is measured from it. Adding the last date records the full breeding period.

Can puppies be born at 58 days?

Yes, counted from a mating date that is within the normal range, because conception may have happened days after the mating. Puppies born much earlier than the window may be premature and need a vet.

What temperature means labour is near?

A drop to about 99 °F (37.2 °C) or below usually means labour within 8–24 hours.

Can I use this for a pregnancy confirmed by my vet?

Yes. If your vet gave you an LH surge or ovulation date, use it for a tighter window. If they estimated the stage from an ultrasound, ask which day of pregnancy they counted from and enter the matching date.

How many puppies will my dog have?

Litter size depends mostly on breed and the mother’s size and age; small breeds often have one to four puppies and large breeds more. An x-ray from about day 55 is the most reliable way to count them before birth, which also tells you when labour is finished.

What should a pregnant dog eat?

Her usual complete diet for the first weeks. Energy needs rise mainly in the last three weeks (AAHA lists about 3 × RER) and climb further while nursing; many vets switch to a puppy or growth food late in pregnancy. Ask your vet for her plan.

Related calculators and guides

• Dog heat cycle calculator — predict the next heat.
• Puppy development stages — what happens after birth, week by week.
• Puppy weight calculator
• All PupGauge calculators

Sources

• Davidson AP. Whelping and Queening in Dogs and Cats. Merck Veterinary Manual, professional version (reviewed June 2025).
• Concannon PW. Canine pregnancy: predicting parturition and timing events of gestation. In: Recent Advances in Small Animal Reproduction. International Veterinary Information Service; 2000.
• American Kennel Club. Dog pregnancy: signs, care and preparing for puppies (with Dr Jerry Klein, AKC Chief Veterinary Officer).

See our methodology page for how PupGauge builds its calculators.