Dog Pregnancy Calculator

A dog whelps about 63 days after ovulation, or 56 to 70 days after breeding

How long a dog's pregnancy lasts depends on which day you start counting from. Counted from ovulation, the average is 63 days. Counted from the day blood progesterone first rises (the LH surge), almost every dog whelps within 64 to 66 days. Counted from the breeding date, the range widens to 56 to 70 days, because the day of breeding and the day of actual fertilization can differ by several days.

Enter whatever you know (first and last breeding dates, ovulation date, LH surge date or an ultrasound measurement) and this calculator gives you a due date and an expected window. It also shows which day of pregnancy today is, and lays out what to do and when, from the first ultrasound to X-rays, temperature checks and the day to call your vet, as a dated schedule and a pregnancy map. If the first breeding was on October 1, 2026, the due date is Thursday, December 3, 2026, and the expected window runs from Thu, Nov 26 to Thu, Dec 10.

Why work out the due date ahead of time

If you only know one due date and wait for it, it is easy to miss the important moments. Over a pregnancy, several tasks come around that depend on the calendar.

• Timing tests: An ultrasound done too early can miss a real pregnancy, and an X-ray only works once the puppies' bones have hardened. Counting back from the due date lets you book vet visits on the right days.
• When you only know the breeding date: The window from a breeding date alone is longer than two weeks. An ultrasound measurement around day 28 after ovulation can narrow the due date again, so it helps to know that date in advance.
• Changing and increasing her food: Keep her food the same for the first two thirds of the pregnancy, then increase it little by little after 6 weeks. In the last 3 weeks it can rise to as much as 1.5 times her usual amount.
• Preparing for the last week: Before labor, her rectal temperature drops below 99°F (37.2°C). You can only notice the drop if you have taken her normal temperature beforehand.
• Deciding when to go to the vet: If the expected window has ended and there is no labor, do not keep waiting; get her examined. Knowing that day in advance cuts down the time spent hesitating.
• Breeds that often need a C-section: In a UK survey, more than 80% of Boston Terrier, Bulldog and French Bulldog births were by C-section. Surgery plans should be made well before the due date.

How it is calculated

Whichever basis you enter, the calculator first finds the day that corresponds to the LH surge and adds 65 days to get the due date. Ovulation happens 2 days after the LH surge, so an ovulation date or a breeding date has 2 days subtracted to convert it to the LH surge. The "day of pregnancy" on screen is an approximate count with the ovulation day as day 0.

The LH surge date comes from progesterone testing

If your vet measures progesterone every few days during heat, you can find the day the level first rises (about 2 ng/mL, at least double the baseline). In the study by Kutzler et al. (2003), predictions that added 65 days to that day were correct within ±1 day in 67% of dogs, within ±2 days in 90%, and within ±3 days in all of them. If your lab report states an ovulation date, enter that date in the ovulation field.

Counting back from ultrasound measurements

When you only know the breeding date, the size of the fetuses on ultrasound is the best way to correct it. The Merck Veterinary Manual uses different measurements before and after day 40. The values in the formulas below are in cm, and the result is the number of days of pregnancy counted from the LH surge. Subtract that number from 65 to get the days left until whelping.

The Merck manual gives the error of these formulas as ±3 days. Kutzler et al. (2003) reported that the ultrasound prediction was within ±1 day in 75% of dogs and within ±2 days in 87%, and that measurements taken around 30 days after the LH surge were the most accurate. In the same study, small dogs of 9 kg (20 lb) or less and giant dogs over 40 kg (88 lb) were affected by body size. If your report is in mm, switch the calculator's unit to mm. Entering 15 mm in the cm field makes the pregnancy day come out almost ten times too large.

Example: a dog bred around October 1, 2026

For the same pregnancy, the due date and window change like this depending on which date you know. With the breeding date alone, the window is more than 15 days wide, but with the ovulation date or the LH surge date it narrows to 3 days.

Week by week: mom, puppies and what to do

The days below are approximate, with the ovulation day as day 0. If you calculated from the breeding date, the real timing can be off by a few days either way. On the pregnancy map under the calculator, pressing a week button shows the same content matched to your dates.

Signs of labor and when to go to the vet right away

A change in body temperature is the most reliable way to tell whether labor is near. According to VCA Animal Hospitals, in most dogs the rectal temperature falls below 99°F (37.2°C) within the last 24 hours. In stage 1 labor she may be restless, pant and dig a nest, and this stage can last as long as 24 hours.

• Call right away: She strains hard for more than 30 minutes and no fluid or puppy appears
• Call right away: After delivering one or more puppies, she does not strain again within 2 hours
• Call right away: She keeps straining for hours and no puppy comes out
• Get her examined: The expected window has ended and there is no labor, or her temperature dropped and a day has passed without labor starting
• After birth: Bloody or foul-smelling discharge 24 to 48 hours or more after delivery

Note Green fluid that comes out while she is delivering a puppy can be normal. But if only green discharge keeps coming and no puppy appears, the placenta may have detached early, so call right away (AKC).

Differences by breed and litter size

Studies show that average pregnancy length differs slightly by breed. In the study by Okkens et al. (2001), in which dogs were bred once on a progesterone-timed day, the average was 61.4 days: German Shepherd 60.4, Labrador Retriever 60.9, Doberman 61.4 and West Highland White Terrier 62.8 days. Litter size matters too. Eilts et al. (2005) reported that dogs with 4 or fewer puppies carried about 1 day longer on average than dogs with 5 or more.

These differences are only 1 to 2 days, much smaller than the window from the breeding date (15 days or more). So this calculator does not shift the due date by breed and instead shows the window honestly. Where breed really matters is the birth method. In a 2004 UK survey of purebred dogs (Evans and Adams 2010), more than 80% of Boston Terrier, Bulldog and French Bulldog births were by C-section. Other breeds with high rates include the Mastiff, Scottish Terrier, Miniature Bull Terrier and Pekingese. For such breeds, turn on "Breed that often needs a C-section" and plan the surgery with your vet around 2 weeks before the due date.

Common mistakes

• Counting from the start of heat: This is not like a human pregnancy counted from the last period. The gap between the first day of heat bleeding and ovulation varies a lot from dog to dog, so it is not used as a basis.
• Treating 63 days as an exact date: From the breeding date, whelping at 56 days or at 70 days is still normal. Look at the start and end of the window, not just the due date.
• Mixing up ultrasound units: The formulas are in cm. A mm value entered in the cm field gives an absurdly large number of days. The calculator asks you to check the unit when the result goes past day 66.
• Using a measurement for the wrong stage: GSD and CRL are for before day 40, and BP and BD for after day 40. If the stage does not match, a warning appears under the result.
• Taking her temperature only once: Body temperature moves up and down during the day. In the last week, take it 2 to 3 times a day so you know her normal value and can tell when it drops.
• Waiting past the due date: If there is still no labor the day after the expected window ends, do not wait longer at home; get her examined.

Limits and cautions

• The dates are approximations counted from research averages. Follow your vet's tests for confirming a pregnancy and judging labor.
• The breeding-date calculation assumes breeding and ovulation fell close together. If real ovulation was a few days earlier or later, the weeks and schedule on the map shift by the same amount.
• Ultrasound accuracy depends on body size. In Kutzler et al. (2003), predictions for small dogs of 9 kg (20 lb) or less and giant dogs over 40 kg (88 lb) were affected by the mother's body weight.
• The 1 to 2 day differences by breed and litter size are not included. Cats have a different pregnancy length and cannot be counted with this calculator.
• The dates and values you enter are calculated only inside your browser and are not sent to a server. If you press "Copy link", those values are put into the address.

Sources

• 01Concannon PW(1986), Canine pregnancy and parturitionVet Clin North Am Small Anim Pract. 64 to 66 days from the LH surge to whelping, 56 to 70 days from breeding, ovulation 2 days after the LH surge, implantation around day 17, fetal bones on X-ray after day 45
• 02Concannon PW(2011), Reproductive cycles of the domestic bitchAnim Reprod Sci. Pregnancy of 65 ± 1 days (from the LH surge)
• 03Kutzler MA et al. (2003), Accuracy of canine parturition date prediction from the initial rise in preovulatory progesterone concentrationTheriogenology. First progesterone rise (≥1.5 ng/mL, mean 2.02) + 65 days; ±1 day 67%, ±2 days 90%, ±3 days 100%
• 04Kutzler MA et al. (2003), Accuracy of canine parturition date prediction using fetal measurements obtained by ultrasonographyTheriogenology. Whelping = 65 − estimated days; ±1 day 75%, ±2 days 87%; most accurate at day 30; body weight affects small and giant dogs
• 05Merck Veterinary Manual: Pregnancy Determination in Bitches and QueensUltrasound formulas (GSD and CRL before day 40, BP and BD after day 40, in cm, ±3 days), false negatives before day 21, relaxin 22 to 27 days after breeding, X-ray at 42 to 45 days, puppy count after day 55
• 06dvm360: Performing ultrasound to evaluate pregnancy (Proceedings)Estimated days are counted from the LH surge, measurements in cm; whelping 65 ± 1 days after the LH surge; heartbeat 21 to 22 days after the LH surge
• 07Lopate C(2008), Estimation of gestational age and assessment of canine fetal maturation using radiology and ultrasonography: a reviewTheriogenology. Ultrasound from 19 to 21 days after the LH surge, X-ray from day 45
• 08VCA Animal Hospitals: Pregnancy in Dogs57 to 65 days from breeding, average 63; an ultrasound after day 28 is mostly reliable; increase food gradually after 6 weeks; up to 1.5 times in the last 3 weeks
• 09VCA Animal Hospitals: Whelping in DogsTemperature below 99°F (37.2°C) in the last 24 hours, stage 1 labor up to 24 hours, 30-minute straining and 2-hour gap guidelines, discharge after birth
• 10American Kennel Club: Dog Reproductive Cycle63 days from ovulation, 65 to 66 from the LH surge, 58 to 72 from the first breeding; temperature drop 12 to 24 hours before labor; green discharge
• 11Okkens AC et al. (2001), Influence of litter size and breed on the duration of gestation in dogsJ Reprod Fertil Suppl. Single breeding, mean 61.4 ± 1.5 days (58 to 65 days), averages by breed
• 12Eilts BE et al. (2005), Factors affecting gestation duration in the bitchTheriogenology. Litters of 4 or fewer run about 1 day longer on average; no effect of age or parity
• 13Evans KM, Adams VJ(2010), Proportion of litters of purebred dogs born by caesarean sectionJ Small Anim Pract. 2004 UK survey of 151 breeds; over 80% for Boston Terrier, Bulldog and French Bulldog

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