A Sphynx needs a medium carrier, around 22 inches long inside, tall enough to sit upright and wide enough to turn and curl into a comfortable ball. On measurements alone she resembles any other medium-sized cat, but stopping at measurements buys the wrong carrier, because everything about her hairless body changes what the inside of that box should feel like. Bare skin meets every surface directly, loses heat to moving air, and picks up dirt and oils that a coated cat's fur would shrug off, so the carrier's lining, ventilation pattern, and ease of cleaning matter as much as its dimensions when you choose for this breed.
Lining the box for skin, not fur
Skip carriers whose interior is mostly exposed mesh or coarse plastic ridges, because a Sphynx shifting position during a drive can rub herself sore against textures a furry cat never notices. Line the floor with a smooth, soft blanket that stays flat rather than bunching, and tuck the edges so her claws and toes cannot tangle in loose folds when she kneads. Fleece and soft cotton both work well; the essential qualities are smoothness against skin, warmth without bulk that steals her turning space, and washability, since a Sphynx leaves skin oils on everything she sleeps on and her bedding needs frequent laundering to stay fresh.
Warm, ventilated, and never sealed shut
The temptation with a chilled Sphynx is to wrap the carrier completely, and that overshoots into a stuffy, overheated box. She needs moving air as much as any cat; she just does not need it blowing straight across bare skin. Choose a carrier with ventilation spread across several sides so air circulates gently, position it in the car away from a direct air-conditioning blast or an open window, and drape a cover over the top only if the room or car is cold, leaving the ends open. Warm the car before a winter journey, keep the carrier off cold floors while you wait at the clinic, and watch her signals: a Sphynx curled tight with ears cold to the touch needs more warmth, while one stretched out flat and restless is telling you the setup has gone too far the other way.
Gentle loading for a cat with no padding
A top-opening carrier earns its place again here, for a different reason than strength: lifting a Sphynx out through a front door drags her skin across the door's lower edge, and her fine skin marks easily. Lower her in from above, supporting her chest and hindquarters with warm hands, and lift her out the same way rather than inviting her to squeeze past a frame. Sphynx cats are famously people-oriented and usually tolerate handling well, so calm, unhurried loading normally works better than speed.
Keeping the setup consistent between trips
Wash the carrier lining after every outing, wipe the interior smooth surfaces, and rebuild the bedding fresh, because oils transferred from her skin build up on surfaces and become the smell and grime of the next journey. Replace blankets that have gone rough or pilled, since the texture that was soft last season may now chafe her. If she travels to a sitter or stays anywhere overnight, send the carrier with its usual blanket rather than a freshly laundered one, because the familiar scent is part of how she settles. Record the carrier size that suits her, the blanket and sweater routine, and how she likes the cover arranged in KinsLe with Family Sharing, so whoever takes her to an appointment recreates the warm, soft setup she expects instead of handing her a bare plastic box.