Dog Pregnancy Calculator, Whelping Due Date & Week by Week Guide
Wondering when your dog will give birth? This dog pregnancy calculator turns a single breeding date into a full whelping plan. Enter the mating date and get the most likely due date, 63 days later, the average canine gestation period measured from ovulation, plus the realistic 61 to 65 day whelping window most dogs deliver inside. Because sperm can survive up to a week in the reproductive tract and ovulation rarely lines up exactly with mating, the calculator also shows the wider 58 to 72 day range vets quote from a single breeding. You will see which week of pregnancy your dog is in right now, the key milestone for that week, from implantation around week 3 to the pre whelping temperature drop below 99°F, and the vet checks that matter: ultrasound confirmation around day 25 to 30 and an X ray puppy count near day 45. The week by week guide below walks through fetal development, feeding changes and whelping box preparation, so nothing catches you off guard. It is built on the same 63 day figure the Merck Veterinary Manual uses, and it is free, private and instant, everything runs in your browser.
Last updated: October 22, 2026
Your result
The formula
Most likely due date = breeding date + 63 days (average canine gestation, measured from ovulation)Whelping window = breeding date + 61 days through breeding date + 65 daysOuter normal range = breeding date + 58 days through breeding date + 68 days (from a single mating)Current week of pregnancy = floor((today − breeding date) ÷ 7) + 1
A worked example
Bella was bred on October 1. Add 63 days and her most likely due date is December 3. Her whelping window opens December 1 (day 61) and closes December 5 (day 65), so night watches start then. When her temperature drops below 99°F, labour usually follows within 24 hours. That is the signal to stay close.
More about the Dog Pregnancy Calculator
How the 63 day figure actually works
The 63 days everyone quotes is measured from ovulation, more precisely from the LH surge just before it, not from the day the dogs mated. Mating and ovulation rarely line up: sperm can survive 5 to 7 days in the reproductive tract, so a single mating can lead to conception days later. That is why vets quote wider ranges from a mating date: the Merck Veterinary Manual lists 56 to 58 days from the first day of diestrus, 64 to 66 from the LH surge, and 58 to 72 from a single mating. The calculator uses the standard 63 day average and shows you the full spread, so you plan around biology, not a single circled date.
The whelping window: days 61 to 65
Day 63 is the average, but healthy puppies arrive anywhere in a roughly five day window, days 61 to 65 after breeding. Treat the due date as the middle of that window, not an appointment: being “early” or “late” by a few days usually just reflects when mating happened relative to ovulation. Have everything ready from day 58, and call your vet if active labour has not started by day 68.
Week by week pregnancy milestones
Weeks 1 to 2: fertilisation and the journey to the uterus, no visible changes, keep her routine normal. Week 3: implantation; appetite may dip and nipples may enlarge slightly. Week 4: fetuses develop eyes and spinal cords; an ultrasound can confirm pregnancy around day 28. Week 5: toes, claws and whiskers form and steady weight gain begins. Week 6: rapid growth with a visibly swelling belly, start transitioning to puppy food. Week 7: puppies nearly fully formed; she may shed belly hair as mammary glands develop. Week 8: nesting behaviour starts and milk may appear; the X ray puppy count happens around day 45. Week 9: her temperature drops below 99°F (37.2°C) 12 to 24 hours before labour, keep her close and your vet’s number closer.
Vet visits and feeding during pregnancy
Three visits matter most: an ultrasound around day 25 to 30 to confirm the pregnancy and check fetal heartbeats (it cannot count puppies reliably), an X ray near day 45 to count skulls and spines for the birth plan, and a final check in weeks 8 to 9. Feed her normal food for the first five weeks, then gradually increase to 25 to 50% more of a high quality puppy formula. Never supplement calcium without veterinary advice, excess causes more harm than a shortage.
Setting up the whelping box
By week 8, set up the whelping box in a quiet, warm, draft free corner she already likes, a large sturdy box or kiddie pool with washable bedding works well. Let her sleep in it for a week so it smells like home before labour starts. Keep it away from household traffic but somewhere you can check quietly at night, and keep a low heat source nearby (never directly under newborns) for the first week after birth.
More tools for pet parents
Once the puppies arrive, our Dog Age Calculator converts their age to human years as they grow, and the Cat Age Calculator does the same for feline housemates. Setting up an aquarium instead? The Fish Tank Stocking Calculator tells you exactly how many fish your tank can hold. You will find all of these and more on our Pets hub, free, private, and built for real pet parents.
Two breeding dates, one honest window
Suppose your dog was bred on March 10. Adding the standard 63 days gives a most likely due date of May 12, and the usual 61 to 65 day whelping window runs from May 10 to May 14. Night checks and a ready whelping box should start before that window opens, from about day 58, which in this example falls on May 7, so nothing depends on one circled date.
If she was bred twice, say on March 10 and again on March 12, run the calculator from the first date and treat the second date as the far edge of your uncertainty. Puppies conceived from the later mating can arrive up to two days after the window you calculated from the first one, so a sensible watch period here stretches from May 7 through to about May 16.
Temperature checks without the common errors
In the final week, take her temperature at the same two times each day and write the readings down rather than trusting memory. A single low reading means little on its own, because normal readings wander during the day. What you are watching for is a clear drop below her own recent pattern, finishing under 99°F, which is the signal the existing guide links to labour within roughly a day.
The common mistakes are rushing the reading, taking it right after exercise or a meal, and panicking over one odd number. Keep her calm, use the same thermometer each time, and compare today against the last three days of your own notes. A steady downward trend plus restlessness and nesting is far more trustworthy than any single measurement taken in a hurry.
Waiting at home versus calling the vet now
Plenty of waiting is normal: a quiet dog inside her 61 to 65 day window, eating less and rearranging her bedding, usually needs company and observation rather than a car journey. The balance tips when the calendar runs out. If active labour has still not started by day 68 from breeding, that is a call the vet situation, not a wait one more night situation, because the dates no longer fit ordinary variation.
Treat this calculator as a planning tool, never as a diagnosis. It cannot see puppy numbers, puppy size, or how your individual dog is coping, and it cannot rule out a false pregnancy, where hormone changes mimic the real thing convincingly. Whenever what you are seeing and what the dates say disagree, believe what you are seeing and get hands on veterinary advice.
One more preparation pays for itself in the final week: brief the household before the window opens. Other dogs should have a separate sleeping arrangement ready, small children should know the whelping corner is out of bounds, and one adult should be nominated to keep the birth notebook, because times and weights blur together at three in the morning. Calm logistics are part of good care, and they are far easier to arrange on day 55 than during the first contraction.
How to use the Dog Pregnancy Calculator
- Enter the breeding (mating) date, use the first date if she was bred more than once.
- Click “Calculate due date” to get the due date, the whelping window and her current week.
- Read the milestone for her current week and book the matching vet visit.
- Set up the whelping box by week 8 and start twice daily temperature checks.
Frequently asked questions
What is the whelping window?
The five days, 61 to 65 after breeding, when most dogs give birth, with day 63 the average. Healthy deliveries anywhere inside this window are normal. Have the whelping area ready from day 58, and call your vet if labour has not started by day 68, or she strains over two hours with no puppy.
When should I take my pregnant dog to the vet?
Book three key visits: around day 25 to 30 for an ultrasound to confirm the pregnancy and check fetal heartbeats, near day 45 for an X ray to count puppies, and a final check in week 8 to 9 to discuss the birth plan. Call sooner if you see abnormal discharge, she stops eating for over 24 hours, or seems severely lethargic.
How do I know my dog is going into labour?
The most reliable sign is a rectal temperature drop below 99°F (37.2°C), labour usually starts within 12 to 24 hours. Watch also for restlessness, nesting and digging at bedding, loss of appetite, panting or shivering, and visible abdominal contractions. Stage one labour can last 6 to 12 hours before the first puppy arrives.
How long are dogs pregnant?
About 63 days, roughly nine weeks, measured from ovulation. Measured from a mating date the normal range is wider: 58 to 72 days, because mating and ovulation rarely coincide. Most dogs whelp between days 61 and 65. Deliveries before day 58 are considered premature and need urgent veterinary care.
How do I calculate my dog's due date from the mating date?
Add 63 days to the mating date for the most likely due date, and prepare for whelping within a 61–65 day window. Schedule a vet ultrasound around days 25–30 for confirmation and an X-ray around day 45 to count puppies.
My dog was bred on two different days. Which date should I enter?
Enter the first breeding date, because conception from that mating sets the earliest realistic due date, then mentally extend your watch period by the gap between the two matings. If the matings were two days apart, puppies could reasonably arrive up to about two days later than the window calculated from the first date alone.
She is past day 65 and showing no signs. What now?
Stay calm but stop simply waiting. Day 65 is the far edge of the usual window counted from breeding, and the guidance used by this calculator is to contact your vet if active labour has not started by day 68. Call earlier if she seems distressed, unwell, or stops eating entirely, because those signs matter more than the calendar.
I only know the breeding date roughly. Is the result still useful?
Yes, as long as you widen everything by your uncertainty. If the mating happened sometime within a three day span, use the earliest possible date in the calculator and then add those three days to the far end of your watch period. You get a longer, vaguer window, but it still tells you when to start preparing and watching.
Could the signs I am seeing be a false pregnancy instead?
They could. False pregnancy can produce nesting, mammary development, appetite changes, and even mothering of toys, all without a single puppy. Dates alone cannot separate the two, which is why the ultrasound around day 25 to 30 matters so much. If that check never happened and the due window passes quietly, ask your vet to examine her rather than guessing.
When does day one of the count actually start?
For this calculator, day one is the breeding date you enter, and the 63 days are added from there, which is why a March 10 mating produces a May 12 due date. That convention is simple and consistent, but remember the biology sits underneath it: fertilisation may have happened days after mating, which is exactly why the result is presented as a window, not a promise.