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ARM & Hammer Ultra Last Clumping Cat Litter Unscented MultiCat 18 Lbs. Pet Friendly with Baking Soda Odor Control Litter Review

By Dr. Lena Ortiz · Canine wellness writer · Published 2026-05-24 · Updated 2026-06-28

4.3 (6,900) Amazon rating$15.9910,000+ bought last month

Our verdict

Arm & Hammer Ultra Last leans on the brand's baking soda heritage for unscented odor control in a multi-cat clumping litter, and its 4.3 star average across nearly 7,000 reviews and roughly 10,000 units bought last month point to a dependable, high volume everyday choice.

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Best for

Multi-cat households that want unscented baking soda odor control from a well known, widely available brand.

Skip if

You're looking for a scented litter, or you want a plant based or silica alternative instead of a mineral clay clumping formula.

  • Form Granule
  • Weight 18 Pounds
  • Priced 36% below the category median ($24.99 across 153 tracked models)

Our scorecard

4.3/5 overall
  • Owner rating4.3/5

    4.3 average across 6,900 owner ratings

  • Popularity3.9/5

    6,900 owner reviews, more than most models here

The overall score is owner satisfaction weighted by how many reviews back it, so a high rating from few reviews counts for less. The bars below show where this model stands against the other dog and cat food, health, gear and grooming we track in this category on price, popularity and size. Context, not marks against it, and our read of the data, not a lab test.

Overview

["This 18 lb bag of Arm & Hammer Ultra Last is a clumping litter built around Arm & Hammer's baking soda odor control system, aimed at multi-cat households that need pet friendly, unscented performance without fragrance. The Material Type is listed as mineral and plant derivatives, a step beyond straight clay.", "The unscented formula is designed to lean entirely on baking soda's natural odor absorbing properties rather than added fragrance, which suits owners and cats who prefer no scent at all. As a clumping litter, day to day maintenance still follows the familiar scoop and top off routine.", "At $15.99 for 18 lb, it's competitively priced for a multicat clumping formula from a major national brand. With about 6,900 reviews averaging 4.3 stars and roughly 10,000 units bought in the past month, it's one of the higher volume sellers in this lineup."]

Pros

  • Baking soda based odor control from an established brand
  • Unscented formula for households that avoid added fragrance
  • Formulated specifically for multi-cat use
  • Competitively priced 18 lb bag
  • High sales volume with about 10,000 units bought last month

Cons

  • No added fragrance means less masking scent if odor control alone isn't enough
  • Mineral clay based formula, so more dust than plant based or crystal litters
  • 4.3 star average trails a couple of the higher rated options in this list

Specifications

Form
Granule
Weight
18 Pounds

Performance notes

Material Type is listed as Mineral and Plant Derivatives rather than pure clay, reflecting Arm & Hammer's baking soda forward formulation, while Item Form remains Granule for standard clumping performance. The unscented, multicat positioning targets pet friendly odor control without added fragrance.

What buyers say

Roughly 6,900 reviews averaging 4.3 stars, combined with about 10,000 units bought in the past month, show this is a high volume, well established seller, even if its rating sits slightly below the top performers in this litter lineup.

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Frequently asked questions

Is this litter scented?

No, this is the unscented variant, relying on Arm & Hammer's baking soda odor control system instead of added fragrance.

Is this formula suitable for a single cat household?

It's marketed and formulated for multi-cat use, but a single cat household can use it too, and the litter will likely last longer between full changes with just one cat.

What makes this different from a standard clay litter?

The Material Type is listed as mineral and plant derivatives rather than pure clay, which reflects Arm & Hammer's baking soda based approach to odor control, though it still clumps and scoops like a traditional clay litter.

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