Quick answer: A good DIY travel litter box is a lidded storage tub of about 40 x 30 cm with a side entrance and a row of vent holes high on the walls, so ammonia rises out rather than pooling inside. Fill it with 3 to 4 cm of the cat's usual litter, line it for easy emptying, and open it at every rest stop.
Long drives, moves and hotel stays all leave a cat without its usual tray. A closed box with no airflow quickly smells strongly of ammonia, which some cats will refuse to use. A travel box needs to be small and spill-proof, but it still has to breathe.
This guide focuses on a portable box. For home enclosures and ventilation in more depth, see our litter enclosure and ventilation hub.
Why Ammonia Builds Up in Small Boxes
As urine breaks down it gives off ammonia, a light gas that drifts upward. In a sealed tub, it has nowhere to go, so the air inside grows stronger each time the cat uses it. Vents placed high on the walls let the gas escape before it builds up, while the lid still keeps litter from spilling when the car moves.
Choosing the Tub
A rigid plastic storage tub of about 40 x 30 cm and at least 25 cm deep fits most adult cats and still sits on a car footwell or hotel floor. Choose one with a clip-on lid. Smooth, non-porous plastic wipes clean easily. Avoid soft fabric boxes for long trips, as they absorb odour and are hard to wash.
Larger cats may need a 50 x 35 cm tub. The cat should be able to turn around inside without stepping out.
Cutting the Entrance and Vents
Cut an entrance of about 18 x 18 cm in one short side, starting 10 cm above the base so litter stays inside. File the edges smooth. Then drill a row of 8 to 10 mm holes about 3 cm below the lid on both long sides, roughly 4 cm apart. On a 40 cm side, that gives about nine holes per side.
Liners and Litter Depth
Line the tub with a disposable liner or a bin bag folded over the rim, so you can lift out the litter at a stop. Use 3 to 4 cm of the cat's usual litter. That is shallower than at home, which keeps weight and spills down, but still deep enough to dig. Familiar litter matters more on a trip than at home, because everything else is new.
ASPCA guidance on litter box problems notes that sudden litter changes can cause a cat to avoid the box.
Setting It Up in the Car
Never let the cat roam free in a moving car. Use the travel box at rest stops: park, close the doors and windows, open the carrier and let the cat step into the box placed in the footwell or rear seat. Give it a few quiet minutes. International Cat Care on travelling with your cat covers safe carriers and journey planning.
Setting It Up in a Hotel Room
The bathroom floor is usually the best spot: it is quiet, easy to clean and away from where you sleep. Put the tub on a towel to catch scattered litter. Show the cat the box as soon as you arrive, then put food and water in a different corner of the room.
Odour Control on the Move
Scoop at every stop and seal the waste in a small bag. A sprinkle of plain baking soda under the liner helps absorb odour. Avoid scented sprays and plug-in fresheners inside the car or box; strong smells can put the cat off. Keep windows slightly open when parked, if it is safe to do so.
Our guide to apartment litter odour fixes covers more odour control methods that also work on the road.
Packing a Litter Kit
- The tub with its lid and two spare liners per day of travel.
- A sealed bag of the usual litter, enough for 3 to 4 cm per refill.
- A small scoop and a roll of waste bags.
- Paper towels, unscented wipes and a small bottle of water.
- A towel to go under the box in hotel rooms.
Cleaning Between Stops and After the Trip
Lift out the liner and dispose of it properly when it is soiled, then wipe the tub with water and a mild unscented cleaner. Let it air dry before adding a fresh liner. After the trip, wash the tub thoroughly with warm water and dish soap, rinse well and leave it to dry in the open air.
Our guide to how often to clean a litter box gives the routine for home use.
Getting the Cat Used to It Before You Leave
Set the travel box up at home a week before the trip, next to the usual tray, and put a scoop of used litter in it. Most cats will try it once or twice. A cat that has used the travel box at home is far more likely to use it in an unfamiliar room.
Using the Box During a Move
Moving house is stressful for cats. Keep the travel box in a quiet, closed room on moving day, with the carrier, food and water. Move the home tray last and set it up first in the new place. International Cat Care on moving house with your cat has a full plan for the day.
When the Cat Will Not Use the Travel Box
Some cats hold on for hours when stressed. Offer the box at every stop, but do not force the cat in. If a cat has not passed urine for more than 24 hours, or strains without producing anything, contact a vet promptly. Straining can signal a urinary blockage, which is an emergency, especially in male cats.
Renters and Hotel Policies
Check the hotel's pet policy before booking, and bring enough towels to protect the floor. In a rental, keep the box on a washable mat. Our renter-friendly litter solutions covers options that leave no marks behind.
Travelling With Two Cats
Two cats can share a travel box for a short trip, but many prefer their own, especially in a strange room. If space allows, bring a second, smaller tub. In a hotel room, set the boxes in different corners so neither cat has to pass the other to reach one. Our multi-cat litter station layout explains why separate spots reduce stress at home too.
Using the Tub at Home Afterwards
The travel tub makes a handy spare box for a guest room or a sick-day setup. Remove the liner, wash it and keep it in a cupboard with the litter kit, ready for the next trip. In a small home, it can also serve as a temporary second tray while you build a permanent enclosure; our small apartment cat home hub covers where to put one.
Choosing Litter for a Trip
Clumping litter is the easiest to scoop at a roadside stop, but it is heavy. Lightweight clumping versions cut weight in the car. Pine or paper pellets weigh less still but may not suit a cat that has never used them. The safest choice is the same litter the cat uses at home, packed in a sealed bag.
Travel Litter Box Questions
How do I make a travel litter box for my cat?
Use a lidded plastic tub of about 40 x 30 cm. Cut an 18 cm entrance in one short side, 10 cm above the base, and drill 8 to 10 mm vent holes 3 cm below the lid along both long sides. Line it and add 3 to 4 cm of the usual litter.
Where should the vents go on a travel litter box?
High on the walls, about 3 cm below the lid. Ammonia from urine is lighter than air and rises, so high vents let it escape before it builds up inside. Low vents near the litter let gas pool and can leak litter when the car moves.
Can my cat use the litter box while the car is moving?
No. A cat should stay in a secured carrier while the car is moving. Offer the travel box at rest stops instead: park safely, close the doors and windows, open the carrier, and give the cat a few quiet minutes to use the box.
How much litter should I put in a travel litter box?
About 3 to 4 cm of the cat's usual litter. That is shallower than at home, which keeps weight and spills down, but deep enough for digging and covering. Bring a sealed bag with enough for a fresh refill every day of the trip.
What if my cat will not use the litter box when travelling?
Offer it at every stop without forcing the cat in, and keep the litter familiar. If the cat has not urinated for more than 24 hours, or strains without passing anything, contact a vet promptly, as straining can signal a urinary blockage.
