A carrier or crate is one of those purchases that feels simple until you’re standing in front of a wall of options, sizes and materials. Getting it right matters more than it might seem: the correct size and a proper introduction make the difference between a crate your dog or cat sees as a safe den, and one they associate with stress. Here’s how to choose well and train your pet to actually like it.
Choosing the right size
According to the RSPCA, a dog’s crate “should be big enough for them to stand, turn around, lie down and stretch in” — that’s the baseline test, regardless of breed or size. As a practical guide, your dog should be able to stand up fully without stooping, walk through the door easily, turn around without difficulty, and lie fully stretched out on their side with room to spare. For puppies, the RSPCA recommends buying a crate sized for the dog they’ll grow into rather than their current size, since it saves buying multiple crates as they grow — but there’s an important travel caveat: don’t transport a puppy in their full adult-sized crate, since a smaller, more enclosed space actually protects them better in a moving vehicle by limiting how far they can be thrown around if you brake suddenly.
Cat carriers work on a similar stand-turn-lie-down principle, though cats generally prefer a more enclosed, den-like space than the open wire crates common for dogs. A hard-sided carrier with a top-opening lid tends to work best for vet visits, since it lets you lift a nervous cat out from above rather than dragging them out through a front door under stress.
Materials and features worth having
Wire crates offer good ventilation and visibility, which some dogs find reassuring and others find exposing — a crate cover can help nervous dogs feel more secure inside a wire design. Plastic/hard-sided carriers offer more enclosed security and tend to be required for airline travel. Soft-sided carriers are lightest and easiest to store but offer less structural protection, so they’re better suited to calm, smaller pets on short trips than for a dog or cat who might scratch or chew their way out.
Training your pet to actually like the crate
The RSPCA’s approach to crate training is built around a simple principle: “the crate should always be associated with something pleasant.” Their recommended process happens in gradual, small steps rather than all at once. Start by introducing the crate with the door open, tossing in treats or feeding meals inside so your dog chooses to walk in voluntarily. Once they’re comfortable eating and relaxing inside with the door open, begin closing it for very short periods while you’re in the room, then gradually build up the time and start stepping out of sight for brief spells before working up to longer, independent periods.
Patience matters here more than speed — the RSPCA is explicit that training should happen “in a series of small steps,” and rushing the process is one of the most common reasons crate training goes wrong. If your dog whines or scratches at first, resist the urge to let them out immediately, since this can teach them that protesting works; instead, wait for a brief calm moment before opening the door.
What a crate should never be used for
This is worth being direct about: the RSPCA states plainly that “crates must never be used as a punishment or to prevent unwanted behaviours.” A crate used as a timeout spot for bad behaviour quickly stops being the safe, calm space it’s meant to be, undermining months of careful training in a single use. Crating also isn’t meant for all-day confinement — RSPCA guidance suggests around three hours as a sensible maximum for a well-trained adult dog, with much shorter periods for puppies, who also need regular bathroom breaks their bladders simply can’t hold off for long stretches.
Using a crate or carrier for car travel
Many owners use the same or a similar carrier for both home and car journeys, but it’s worth checking a product is actually rated for vehicle travel before relying on it there, since the structural demands are different from a crate used purely at home. A carrier or crate used in a car should sit securely, ideally restrained by a seatbelt or a dedicated anchor point, rather than sliding freely in the boot or on a seat during braking. For cats specifically, a hard-sided carrier is generally preferable for car travel over a soft one, since it offers more protection if the car brakes suddenly, and it’s worth introducing your cat to short practice trips before a longer or more stressful journey, like a first vet visit, so the carrier and the car itself feel less novel and alarming in the moment.
The bottom line
A well-chosen crate or carrier, sized so your pet can stand, turn and stretch comfortably, becomes a genuine safe space rather than a source of stress — but only with patient, reward-based introduction and a firm rule that it’s never used as punishment. Get the size and the training approach right, and most dogs and cats come to see their crate as somewhere they choose to go, not somewhere they’re put.