Cat Pregnancy Calculator: Kitten Due Date & Gestation Timeline
That hopeful guesswork after a cat mates, is she really pregnant, and when are the kittens coming? This cat pregnancy calculator answers both halves. Enter the mating (breeding) date and it estimates the kitten due date using the average 65 day feline gestation period, giving you a realistic delivery window rather than a single uncertain day. You also see how many weeks pregnant she is right now, which development stage the kittens have reached, and the days remaining. Below the calculator sits a full week by week gestation timeline, from fertilisation and the classic "pinking up" of the nipples around week 3 to the nesting behaviour of week 9, plus a practical birth prep (queening) checklist so the nesting box, supplies and your vet's number are all ready before labour starts. Everything runs instantly in your browser, free, with no signup.
Last updated: October 22, 2026
Your result
An ultrasound from week 3 to 4 confirms pregnancy, and your vet should see her if labour has not started by day 70.
The formula
Due date = mating date + 65 days (average feline gestation)Normal delivery window = mating date + 61 to 68 daysWeeks pregnant = days since mating ÷ 7, rounded downBefore day 58 counts as premature; no labour by day 70 needs a vetStage = Early (weeks 1 to 3) · Mid (weeks 4 to 6) · Late (weeks 7 to 8) · Queening (week 9+)
A worked example
A cat mated on 1 January 2026 has an estimated kitten due date of 7 March 2026, 65 days later. Her normal delivery window runs from 3 March (day 61) to 10 March (day 68), so the nesting box should be ready and the vet's number close at hand by the first week of March.
More about the Cat Pregnancy Calculator
How the due date math works
Cats are pregnant for about 63 to 65 days on average, roughly 9 weeks, which is why the calculator adds 65 days to the mating date. Unlike humans, female cats are induced ovulators: the act of mating itself triggers egg release, so the mating date is a surprisingly good stand in for conception. That is why this calculator asks for the mating date rather than a last period or ovulation estimate.
Biology is not a perfect clock, so the calculator gives you a delivery window instead of a single day. Days 61 to 68 after mating cover the normal range for healthy litters; anything from day 58 to day 72 can still be normal depending on breed and litter size. If your cat mated over several days, enter the first day, the delivery watch period starts at its earliest.
Litter size nudges the date a little. Larger litters often arrive a touch earlier because the uterus is under more pressure, while a single kitten can comfortably run a day or two late. Choosing the litter size refines the estimate by one day in either direction, a small but honest improvement over a one size fits all number.
Cat pregnancy week by week
Weeks 1 to 2: fertilisation and implantation. There are no visible signs at all. She eats, sleeps and behaves exactly as normal. Keep her routine and diet unchanged; this is not the time for extra food or supplements.
Week 3: the classic "pinking up", her nipples become rosier and enlarged, often the first noticeable sign of pregnancy. A vet can confirm the pregnancy with an ultrasound from about now, and some queens show brief morning sickness or reduced appetite.
Weeks 4 to 5: the abdomen begins to round out and weight gain becomes measurable. This is the right moment to start switching her onto kitten food, which is richer in the protein, fat and calcium she needs for the second half of pregnancy.
Weeks 6 to 7: her belly is clearly swollen, appetite increases and she starts resting more. Many owners can gently feel the kittens moving. Keep her indoors, calm and away from rough play or other animals.
Weeks 8 to 9: the kittens gain final weight and shift into birthing position. Milk production starts, grooming increases and she begins hunting for a nesting spot. This is queening season: the nesting box should already be set up, quiet, warm and familiar.
Birth prep checklist
Nesting box: a sturdy cardboard box or crate in a quiet, warm, draught free room, lined with clean towels or blankets she can knead. Introduce it by week 7 so it smells familiar, do not move it once she starts using it.
Supplies within reach: clean towels, dental floss and blunt scissors (in case a cord needs tying, on vet advice), a small digital scale to weigh newborns daily, and kitten milk replacer in case a kitten needs supplementing.
Vet details: your own vet's number plus the nearest 24 hour emergency clinic, saved where the whole household can find them. Confirm in advance that they handle after hours obstetrics.
The room itself: low light, a closed door other pets cannot push open, food, water and a litter tray nearby so she never has to leave the kittens far. Most queens want you close but not hovering, a chair in the corner beats a crowd.
Signs of labour: when queening starts
About 24 to 48 hours before birth she starts nesting, scratching at bedding, settling and re settling, restlessness and sometimes pacing. Appetite usually drops and she may vocalise more, pant, or groom her belly obsessively.
A practical early warning: her body temperature drops to around 37.8°C (100°F) or below roughly a day before labour. If you have been taking her rectal temperature twice daily in the final week, the dip is the clearest signal labour is imminent.
Labour itself has three stages: contractions begin (restlessness, straining), kittens arrive, usually 10 to 60 minutes apart, each in its own sac that she opens and cleans, and finally each placenta passes, which she will typically eat. A healthy queen needs space, warmth and calm, not an audience.
When to call the vet
Day 70 arrives with no labour, or contractions with no kitten for more than 1 to 2 hours, means the vet needs to see her, potentially urgently. Prolonged straining, a stuck kitten, or green discharge before any kitten is born are all emergencies, not wait and see situations.
Between kittens, gaps of up to 2 hours can be normal if she is resting calmly, but if she is straining hard with no progress for over an hour, or seems distressed, lethargic or in unusual pain, call the emergency clinic rather than hoping.
After birth, watch for retained placentas, heavy bleeding, refusal to nurse, or a kitten that is not feeding within a few hours. Newborns should gain weight daily; a kitchen scale and a simple log turn vague worry into data your vet can act on.
More free pet tools
This calculator is one of the free pet tools in the <a href="/pets/">Pets hub</a> from age converters to health checkers, all free and private.
If you also have a dog expecting puppies, the Dog Pregnancy Calculator gives her whelping due date and week by week guide. And once the kittens arrive, the Cat Age Calculator converts their age into human years as they grow.
From one mating date to a full countdown
Suppose your cat was mated on 10 March 2026. Adding the average 65 days of feline gestation puts her estimated due date on 14 May 2026. The normal delivery window matters more than the single date: day 61 falls on 10 May and day 68 on 17 May, so kittens arriving anywhere in that span are on time. Day 70, the point where a vet should be involved if nothing has happened, falls on 19 May.
Working backwards from that window turns dates into a plan. Set up a quiet nesting box around day 50, 29 April in this example, so she can adopt it well before labour. Expect her appetite to climb through the final third of pregnancy, roughly from day 43 onward, and keep handling gentle and routines steady in the last week, when many queens go off their food and start investigating dark, enclosed spots around the house.
Where due date estimates go wrong
The most common trap is a mating season rather than a mating date. Queens in heat may mate repeatedly over several days, and each mating can trigger ovulation, so kittens in one litter were not necessarily conceived on the same day. If you watched matings on both 10 and 13 March, treat the due window as a range: count 61 to 68 days from the earliest date for the soonest likely arrival, and from the latest date for the far end.
It also helps to know what the calculator cannot do. It performs calendar arithmetic on the date you give it; it cannot confirm a pregnancy exists. A vet can, by palpation in the earlier weeks or ultrasound, which can also check that kittens are alive and developing. That distinction matters because cats can show a false pregnancy, with nesting behaviour and even milk, while carrying no kittens at all, and no date calculation will reveal the difference.
How to use the Cat Pregnancy Calculator
- Enter the date your cat mated, use the first day if she mated over several days.
- Pick the expected litter size if you know it; it refines the estimate by a day.
- Hit Calculate to get the due date, the delivery window, her current week and stage.
- Use the timeline and the birth prep checklist below to plan vet visits and the nesting box.
Frequently asked questions
How long are cats pregnant?
About 63 to 65 days on average, roughly 9 weeks. The full normal range runs from 58 to 72 days, and most healthy litters arrive on days 63 to 67. Delivery before day 58 counts as premature, and no labour by day 70 means it is time to call the vet.
How do I calculate my cat's due date?
Add 65 days to the first mating date. That is the estimated due date. Then treat days 61 to 68 after mating as the delivery watch period, when birth is most likely. If she mated over several days, use the first mating for the earliest date and the last mating for the latest.
What are the first signs my cat is pregnant?
Around week 3 her nipples become rosier and enlarged ("pinking up"), often the first visible sign. Increased appetite, mild morning sickness in weeks 3 to 4, and a rounding belly from week 5 follow. A vet can confirm pregnancy with an ultrasound from about week 3 to 4, the only way to know for sure.
When should I take my pregnant cat to the vet?
Book a check up around week 3 to 4 to confirm the pregnancy, then again around day 45 to 55, when an X ray can count the kittens and flag any size concerns. Go sooner if she stops eating, bleeds, or seems unwell, and treat day 70 with no labour as an emergency, not a wait and see.
What are the signs my cat is going into labour?
Nesting and restlessness, a drop in body temperature to around 37.8°C (100°F), reduced appetite, panting and frequent grooming of the belly, these typically appear 24 to 48 hours before birth. Active straining with contractions means kittens are on their way, usually arriving 10 to 60 minutes apart.
How many kittens will my cat have?
The average litter is about 4 kittens, with a typical range of 1 to 8. First litters are often smaller, and some breeds run larger. The most reliable count comes from a vet X ray after day 45, when the kittens' skeletons are visible enough to tally.
My cat mated on several different days, which date should I enter?
Run the calculator twice. Enter the earliest mating date to find the soonest she could reasonably deliver, and the latest date for the other end of the window. A queen who mated on 10 and 13 March, for instance, has a combined window stretching from day 61 after the first mating to day 68 after the last. Prepare the nesting area for the earliest date and do not relax until the latest one passes.
Can a cat have a false pregnancy, and how would I know?
Yes. A false pregnancy can follow an unproductive mating, because the hormonal pattern after ovulation looks similar whether or not kittens were conceived. The cat may gain a little weight, nest, and even produce milk, yet carry nothing. Behaviour alone cannot separate the two, which is why a vet check, palpation in the earlier weeks, or an ultrasound, is the only reliable confirmation that a due date is worth counting toward.
How and when can a vet confirm my cat is pregnant?
A vet can often feel the developing kittens by gentle abdominal palpation from around the third to fourth week, when each one feels like a small, distinct swelling. Ultrasound can confirm pregnancy earlier and has the advantage of showing heartbeats, so it answers not just whether she is pregnant but whether the kittens are alive. One visit in the middle weeks usually settles both the pregnancy and a more confident due window.
Does breed or age change how long a cat is pregnant?
Only slightly. The 61 to 68 day window covers the overwhelming majority of cats regardless of breed, which is why this calculator applies one range to everyone. Very young first time mothers and older queens deserve closer watching near the window rather than a different calculation, their risk lies in labour difficulties, not in a longer gestation. A cat sailing past day 68 with no labour signs needs a vet visit whatever her breed.