The rule of N+1 for litter boxes

Hi everyone, I am a bit confused about the litter box situation in my home. I have two cats, Luna who is a 7 year old calico and Bob who is a 3 year old tuxedo rescue. Currently we have two boxes, one for each cat. I have always heard the rule is N+1, so one per cat plus one extra. Does this mean I should add a third box right now? Or is two enough since they are healthy? I read a thread about my cats suddenly stopped using the boxes and it made me worry that not having enough space could cause issues later. I want to be proactive but do not want to clutter the house too much.

The N+1 rule is a heuristic, not a law. It depends on the volume of waste and the size of the cats. If you have two large cats, two small boxes are effectively one box. Measure your current boxes. If they are under 24 inches in length, you are likely under-provisioned. I would recommend adding a third box only if you notice them waiting or using the same box within 15 minutes of each other. Otherwise, prioritize box size over quantity.

Thank you Walter. My boxes are standard medium size, maybe 20 inches long? I will measure them tonight. Bob is a bit smaller than Luna, so maybe that helps? I am also wondering if the type of litter matters more than the number of boxes. I tried a new clay litter last month and they seemed to dig less.

Oh, I have a similar setup with my deaf girl Orchid and Copper. For me, location was way more important than having a third box. I put one box in the hallway and one in the back bedroom. If you have a third one, make sure it is not near their food or a high-traffic area. I found that having a quiet, low-traffic spot was better than just adding more boxes in the same room. Check out where to place the boxes in a small apartment for some ideas on flow.

Gentle reminder that age and health matter too. My Cleo is 9 and has arthritis, so she needs a box with very low sides. If you are adding a third box, consider if it needs to be accessible for any future mobility issues. I used to think N+1 was set in stone, but then I learned about making boxes accessible for arthritic cats and realized that one accessible box is better than three hard-to-enter ones. For now, with two healthy cats, two well-maintained boxes should be fine, but keep an eye on their habits.

i have two cats too, Duke and Ivy. i just have two boxes and they are fine. my boxes are actually really big, like the cat-sized ones you see in the pet store. i think if your boxes are big enough, you dont need the third one yet. also, keep them super clean. my cats get weird if the litter is clumpy. i scoop twice a day. that might be more important than the number of boxes.

Thanks for the input. I think I will stick with two boxes for now but make sure they are large and very clean. I will also look at the placement to make sure they are not too close to each other. I appreciate the tips on arthritis, good to know for the future. I feel better about the setup now.