Covered or Uncovered Litterboxes: Do Cats Have a Preference?

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By Dr. Sophia Yin

It was late morning midweek and, as usual, we were working on a number of projects in the office. Projects that require quite a bit of teamwork and collaboration. So a few of us were sitting in the office brainstorming when in walks Dante, the office Bengal cat. True to his M.O. Dante announced his arrival with a big MEOW and then promptly walked into his litter box and pooped right in front of us.

A few of the reasons I never wanted a cat were:

  1. I knew I would hate cleaning the litter box.
  2. I knew I didn’t want the litter box to ruin the décor and, since the general recommendation is to have enough litter boxes to equal the number of cats in the household plus one, I would need two.
  3. While I don’t mind seeing my dog poop in the yard and on walks outside, I really did not want a cat walking into my room and pooping a stinky blob right in front of me.

But then I got stuck with Dante, a cat with a history of spraying, and had to adjust. In spite of my loathing for litter, I cleaned his unscented clumping litter (Freshstep®) almost like a compulsive cleaner. The recommendation is to clean the litter box once a day, but I checked it and cleaned it as needed every time I went into the litter box room (which was the bathroom).  Then, so I didn’t have to see his box, I placed it conveniently in a cabinet that housed only it, so it was his personal little potty room. Dante did extremely well and never had any accidents or spraying when he was in this set-up!

Now, interestingly, most of you have probably heard that cats don’t like pottying in covered litter boxes; which is what this setup was, in essence. But according to a recent study, this assumption may be wrong.

Researchers at the Ross University School of Veterinary Medicine took 27 healthy cats between 3 months to 15 years of age and provided them with exclusive access to two litter boxes —one covered and one uncovered—for a 14-day study period. 80% of the cats had been using uncovered litter boxes; however 60% had used covered litter boxes in the past.

Few or none had used the type of litter boxes used in this study though. These litter boxes were different from your standard commercial litter box. That’s because, in order to ensure that the boxes were large enough for all the cats in the study, the researchers, lead by Dr. Emma Grigg, used modified plastic storage tubs (82.5 x 50.2 x 47.3 cm). For the covered boxes, a 15.2 cm hole was cut in the front. For the uncovered litter box, they cut the storage tub walls so that the walls were only 10 cm from the ground. Both boxes were filled with Freshstep®, scented clumping litter and refilled as necessary to maintain the 5cm depth.

The litter boxes were placed side by side in a room and, on day 8, their positions were reversed.  Each day, participants scooped (using identical scoops) and any waste found in the boxes was placed into separate labeled bags. Then Grigg and her colleagues weighed the bags on a daily basis.

The results were clear—in general, cats have no preference.

Once the study was over, the researchers were able to determine that overall there was no preference between covered vs. uncovered boxes; however, some individuals did like one over the other. Four cats (15%) preferred the covered litter box and four cats (15%) preferred the uncovered box. The rest of the cats (70%) didn’t care. Their findings are published in the Journal of Feline Medicine and Surgery.

Why would some cats prefer uncovered boxes?

You might wonder, if there’s so little preference for uncovered, why do so many people think that cats prefer uncovered boxes? Well, for one, commercial covered litter boxes are generally pretty small. That is, they are less than 1.5 times the length of the cat. Maybe that’s ok for an uncovered box, but a cat can feel pretty cramped when he’s stuck in a small space with high sides! In fact, two of the cats in Grigg’s study who chose the uncovered boxes more were large cats. Another theory behind why some cats dislike uncovered boxes is the stench that is trapped inside when humans fail to clean or the pungency of the litter fragrance in scented litters. In general, once a day cleaning was enough to keep most cats happy; however, one study cat who avoided the covered litter box, promptly started using it after the study was over when the litter was changed to a non-scented brand.

Good news

Of course, the good news here is that if you’re getting a cat and prefer to avoid seeing or smelling the stench, go ahead and try a large covered litter box—1.5 times your cat’s size. Just make sure you clean it every single day. However, if your cat is having litterbox issues, it would be good to do a side by side comparison of different litter boxes and litters. This is called a litter box cafeteria.

A second major bit of good news is that this study now gives us license to make litter boxes out of anything that’s the right size. So, currently Dante has two plastic potty palaces made out of storage bins. One is covered but out in plain view. The other is hidden in an empty microwave stand in one of the offices. 

So now when Dante comes in to potty in the middle of one of our meetings, we may still get the announcement and faintly smell a Bengal-cat sized stench, but at least you don’t have to see the ugly act. And you can admire the décor of your hidden litter box!

For ideas on how to hide your litter box, go to

Litter box tips

  1. Clean each litter box at least once a day
  2. The box should be 1.5x the length of the cat
  3. Make sure the litter is deep enough (5 cm or 2 inches deep in general)
  4. Use a litter that the cat likes. Generally cats prefer clumping, non-scented litter but you may need to test for preferences.
  5. Have n + 1 litter boxes  (where n = the number of cats in the household)
  6. Boxes should be located in different rooms or areas of the house.

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17 responses to “Covered or Uncovered Litterboxes: Do Cats Have a Preference?

  1. Love the idea of the litter box. My cat has an high sided one, but still manages to pee over the side of it sometimes. Don’t know if lid will work or not. She was in a cage at the humane society for a year and won’t even play in bags or boxes. Getting her into her kennel for a trip to the vets is next to impossible.

    1. I don’t know if you solved your problem or not, but thought I’d share my solution in case it helps. My previous cat would actually stand up as she peed. So she would start in a squat and then stand up as she was peeing, and would pee outside the box! I never knew what was happening until one day I actually saw her do it (I didn’t know how the urine was ending up outside the box). Maybe your cat is doing the same thing? I went to a home hardware type store and bought a large plastic container (with really high sides; much higher than you would ever find in a litter box). I cut an opening in the front so that it was easier for her to get into the box, I covered the cut plastic with some split open tubing, taping it into place, as the edges were not smooth. It wasn’t pretty to look at, but it worked. Besides a covered box, this would be something to try. Hopefully my directions are clear enough to help you. I hope this helps!

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  3. Based on the photo above and the fact that the boxes are 47.3 cm on the shortest side, I think the hole in the front of the covered boxes must be larger than 15.2 cm. Besides, that’s only about 6 inches.

    As much as i enjoy your posts about dogs, I’m glad to see cats get some attention, too! I like the idea of a covered litter box, but I know myself — if I don’t see the poop, I won’t scoop it. Thanks for sharing this.

  4. Does anyone know anything about a cat who sprays only in the litter box? I have two neutered male cats, both indoor only. They have covered boxes and one of them sprays all over the walls inside the boxes. We tried giving him an uncovered box, but he slowly raises his butt as he pees and just makes a mess. I’m grateful he keeps the mess inside the box, but it’s still gross to clean. Any ideas as to why he does this and could there be any way to change the behavior? Thank you.

      1. They do this in houses with multiple cats to mark “their” litter box. It can keep other cats from using the same one.

  5. I place our cats’ litter box under a coffee table. It seems to work well.

    I threw away the covered litter boxes — I think because the dogs are also in the house the cats felt trapped in there. Also the covered litter boxes that were available were not high enough to accommodate the cats comfortably, but were real eye-sores in the house as well 🙁

    I gave tried to convince my hanndyman husband to make me some ‘side tables’ that would house a three-sided cubby hole for a litte box.

    I’m sure that it woud work brilliantlly/

  6. Thanks for this! Yes! I have had several very large cats over the years and they need very large litter boxes. The largest cat box I’ve ever found was too small for some cats. The researchers’ idea of making their own extra large boxes is genius! I went shopping at a hardware store and found a very large, sturdy plastic box that looks like a gigantic cat box. It works for us.

    I’ve had cats all my life and have used both covered and uncovered boxes. Most of my cats were fine with a covered box as long as it was big enough that they could get into position. However, I find that when a box has a cover it’s easier to forget to scoop often enough. It’s also harder to clean the lidded kinds because you have to clean the lid, too.

    Regarding one box per cat in the family, I recommend this plus one more for people that are having problems with a house soiling cat. At my house, however, I have four cats and they all share one box … as long as it is scooped frequently. If we forget, or if we’re going away and leaving a pet sitter in charge, we add an extra couple of boxes just to be on the safe side.

    Thanks for a very good and practical article! The research is great to know!

  7. Andrea: Thanks for knowing your metric measurements! I did indeed include the wrong measurements. Good thing there’s a picture! Will have the blog updated with the corrections.

    The opening is 27.3 cm x 31.75 cm.
    The bottom of the opening is 10cm from the ground
    For the uncovered box, the sides are 15.2 cm.

    sophia yin

  8. Barbara:

    Dantel cat had a history of urinating vertically in his litter box when he belonged to my aunt and lived with 3 other cats. He did not urinate outside of his box though or spray outside his box. When I got him at 9 years of age (he and other household cats were spraying due to clear household strife!) he stopped urinating vertically in his box. I think he was spraying in his box due to stress! Just not enough stress to spray outside of the box! If he had continued to spray in his box I would have gotten a high sided box immediately or used a covered box.


  9. I have a female cat that has been spade. She is 5 years old. we have another cat that took up here. since then she will not go outside because she is afraid of her. she has a litter box inside. she will use the litter box if I’m in the same room but she gets up during the night and pees on the floor. Help I don’t know what to do!

  10. From your study:
    …Another theory behind why some cats dislike uncovered boxes is the stench that is trapped inside when humans fail to clean or the pungency of the litter fragrance in scented litters.

    …should this read: why cats dislike covered boxes?

    The study that you mention does not seem to account for other predators in the area (dogs, other cats) causing them to choose one type over the other. Also, fearful cats tend to not use the litterbox if there is the possibility of being pounced upon. I recommend using a transparent high sided litterbox (esp for the sprayers) that has been modified to allow an easy hop into the box, but that is not covered, and permits 360 degree view.

  11. I’m looking at building an enclosure for the litter box. Moving into a very small apartment and want it to be smell free, and not obvious. Do boxes have to have vent holes? We ain’t wanting any chance of odor escaping.

  12. My sister was just given a cat and has decided to keep it. She needs to invest in a litter box as soon as possible to train the kitty how to use the bathroom. I did not knwo that uncovered litter boxes are a good idea to avoid your cat feeling cramped and stuck in a small space. This would also be easier to refill the litter box when needed. I will tell my sister.

  13. My cat (6 years old) stopped using a litter box all togeather about 3 years ago. Which has absolutely sucked as one could imagine. (I’ve always kept one (a covered litter box) available to her if she ever felt the need to stop making my life a living hell however). Recently, about 4 months ago, I rescued an injured cat that I ended up keeping. This cat very easily accepted the litter box we made available to her (uncovered). The two cats were kept on separate levels of the house for about 2 and a half months as the new cat was getting vaccinated. When we let them finally see each other and go between the floors, the new cat started to poop behind the toilet on the upper level. I figured eventually that it was probably because her litter box was kept on the lower level, so when she was upstairs and had to go, she would take the easier route. So I put the covered litter box (that i had already set up) in that bathroom and showed the new cat to it. She couldn’t figure out how to get out, so I took the lid off. This was about 3 days ago. However, 2 days ago the cats had a fight and they have been kept on their respective levels of the house for a few days. So the newly placed litter box. The one that was placed for the new cat but not on her respective level of the house. The litter box has fresh poop and pee in it. So I asked my brother if he had let the new cat up, he said no. So somehow my 6 year old cat, the cat that basically hasn’t used a litter box in three years. A litter box that I have tried multiple litters and positions around the house. All this cat needed to start using the litter box was for me to TAKE THE TOP OFF. So this cat. This cat that is the size of a 4 month old cat, mind you. All this cat wanted me to do for three years was take the lid off the litter box. I am both infuriated and incredibly relieved. The amount of money that this cat has cost us in the past few years, to have the solution be so simple is ridiculous and I really hate myself for not figuring it out sooner. I’m sorry for the long comment but I’m sure someone will understand. I hope.

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