Cats are famously opinionated. They’ll sleep in a shoebox but ignore the plush bed you spent a fortune on. They’ll curl up in the sink but hiss at a luxury perch. So when it comes to choosing the right size cat carrier, relying on logic alone won’t help much. You have to consider not just size but behaviour, stress response, physical build, travel environment, and how felines instinctively perceive space.
Let’s unpack what research, veterinary advice, and feline psychology reveal about cats’ preferences when it comes to carrier size.
The Myth of "Bigger is Better"
To the average pet owner, it seems reasonable to assume that more space means more comfort. This assumption applies well to humans — we crave legroom on flights and prefer large hotel beds. However, when it comes to choosing a cat carrier, this logic flips entirely.
Most cats do not like open, expansive spaces — especially when they’re feeling vulnerable or anxious. Larger carriers often create too much room for a cat to slide, jostle, and feel exposed. The extra movement can translate to fear, nausea, and even aggression. In a large space without firm boundaries, a cat's stress levels may spike.
Felines are wired for safety, not spaciousness. Unlike dogs, cats don't see open areas as freedom — they see them as a threat. In moments of stress, a snug, secure cat carrier mimics the confined hiding spots cats instinctively seek out in the wild.
The Science of Containment Comfort
Feline behaviourists consistently find that cats prefer enclosed, tight environments when dealing with stress. Boxes, tunnels, drawers, even the space behind your refrigerator — these locations offer them an immediate sense of safety and control.
Studies conducted by animal behaviour researchers have shown that when introduced to a new environment, cats provided with confined hiding spots adapt faster, eat sooner, and display fewer stress behaviours, compared to cats placed in open spaces.
This preference translates directly into how a cat carrier should feel. It should be compact enough that the cat touches the walls slightly when curled up, but large enough to stand up, turn around, and stretch minimally. This is especially critical when travelling, where the carrier becomes the one familiar constant in a sea of frightening stimuli — road vibrations, strangers, loud sounds, and foreign smells.
Spatial Awareness in Cats: A Different Kind of Geometry
Humans perceive space in terms of distance and orientation, but cats assess it through sensory mapping. Whiskers, for instance, are highly tuned tools that measure spatial width. When a cat enters a space, their whiskers determine whether it's navigable, not their eyes or a conscious sense of dimensions.
In this way, a cat carrier that appears small to us might feel just right to a cat. If the space is snug enough that their body touches the walls gently, the cat receives a calming input through its fur and skin, much like how swaddling soothes a baby.
When the space is too large, on the other hand, the cat is constantly in a state of alert, unable to locate safety boundaries. That’s why many cats scratch at the walls of overly spacious carriers — they are trying to “build” a smaller, defined zone inside them.
How Size Interacts With Other Carrier Features
Size doesn’t operate in a vacuum. Whether a cat carrier is “too big” or “too small” often depends on how its size interacts with other variables:
Shape
A short and wide carrier can feel vastly different from a tall, narrow one, even if both technically offer the same cubic space. Cats often prefer horizontal space over vertical space when in transit, as it allows them to curl into a stable resting position without adjusting to swaying elevation.
Openings
A larger cat carrier may include top-loading or dual-access features. While these features are great for human convenience, they can expose the cat to more outside stimuli. A cat’s preferred carrier often has only one small exit, like a cave with a single way in and out.
Padding
In bigger carriers, it’s tempting to add more bedding or plush padding, but this sometimes creates an unstable surface. Cats like firm footing. If they’re sliding on fluffy padding inside a big carrier, they’re more likely to panic.
Behavioural Clues to the Right Size
Cats show you a lot — if you know where to look. To gauge whether your cat carrier is the right size, observe behaviour inside it:
If your cat constantly shifts position, seems unable to settle, or claws at the walls, the carrier might be too big.
If your cat immediately curls up and stays put, or even enters the carrier voluntarily, you’re likely on the right track.
If your cat refuses to enter altogether, double-check the size and entry point. Sometimes the opening is intimidating, or the carrier's width makes it hard for the cat to orient its body comfortably.
The One-Size-Fits-One Rule
While general guidelines can help, ultimately, the best cat carrier size depends on your cat’s specific personality and physical attributes.
Here are some baseline considerations to keep in mind:
Small-breed cats (under 4 kg): Prefer carriers in the 18-19 inch range with close side walls.
Medium cats (4-6 kg): Do well in 20-22-inch carriers with a rectangular base.
Large cats (6 kg and up): Require space to shift their body weight, but still appreciate tight wall proximity.
This doesn’t mean going up a size blindly. Instead, you might need to test two close sizes to see which one your cat prefers — a 21" versus a 23", for example.
Travel Duration and Carrier Size
Short trips like vet visits require less internal space — cats tend to curl up and stay immobile for the duration. A compact cat carrier with stable walls and minimal movement works best here.
Longer journeys, such as flights or road trips lasting several hours, may benefit from slightly more room. Even then, the ideal isn’t extra space for roaming — it's just enough room to shift sides and stretch limbs briefly.
Avoid using oversized carriers as a way to “treat” your cat — in their mind, a cozy nook beats a sprawling lounge every time.
Temperature Regulation and Size
Another subtle but significant factor is heat conservation. Cats regulate body temperature through their paw pads and ears, but a cold environment, such as an air-conditioned vet’s office or aeroplane cabin, can still stress them out.
A properly sized cat carrier helps trap body heat, especially when lined with a towel or fleece. Oversized carriers dissipate warmth and increase the risk of temperature fluctuations, which some cats are particularly sensitive to.
Multiple Cats and Shared Spaces
A question some pet owners ask is whether it’s ever acceptable to transport two cats in one cat carrier. If the cats are bonded and small, this may be possible — but it requires a carefully sized carrier that feels safe but not crowded.
Interestingly, most cats do not like the shared-carrier setup, even with a sibling. During transport, stress behaviour amplifies, and cats may lash out at each other. In almost all cases, two snug individual carriers are better than one large shared one.
When you lay down multiple cat carrier options at home, cats will often make their preferences known. Some will step right into the one that feels safest; others may sniff and circle until they find one that mimics their nesting instincts.
If your cat picks the smaller option every time, don’t second-guess it. Their choice is likely based on what makes them feel safest and most secure — something even the fanciest human design can’t predict.
And when in doubt, remember this: the ideal cat carrier doesn’t accommodate your cat’s size — it accommodates their stress. This discussion dives into whether cats prefer small, snug carriers or more spacious ones, and why.