Testing the FCMP Outdoor Dual-Chamber Composter: Does It Live Up to the Hype?

This 37-gallon-capacity dual-chamber composter makes it easy to produce 2 high-quality compost piles at once.
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The FCMP Outdoor tumbling composter set up in a yard
Photo: Jenn Ryan for Bob Vila

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Composting is an excellent way to reduce the amount of food waste in landfills and put it to good use in the garden instead. But few people have the time, energy, and means to maintain a large compost pile on the ground. As such, composting containers are popular—especially large, dual-chambered ones that produce two compost piles at once.

The FCMP Outdoor dual-chamber composter is a popular composter with over 11,500 five-star Amazon reviews. The maker, FCMP Outdoor, is a Canadian company that has been in business for more than 40 years. It manufactures outdoor products such as composters, rain barrels, and planters, and it partners with global retailers such as Lowe’s and The Home Depot to sell its products.

I have tested the FCMP Outdoor tumbling composter multiple times over the last 2 years, and I recently tested it again over a 2-month period. While it’s not the absolute best compost bin for my household, my tests continue to reveal it’s a great value because of its dual chambers and convenient size and height.

FCMP Outdoor IM4000 Dual-Chamber Tumbling Composter: At a Glance

The FCMP Outdoor tumbling composter set up in a yard with its door open
Photo: Jenn Ryan for Bob Vila

Rating: 7/10


  • Capacity: 37 gallons
  • Dimensions: 30 inches long by 28 inches wide by 36 inches high
  • Material: 100 percent post-consumer recycled polypropylene plastic and galvanized steel


  • Large door plus overall height and generous ground clearance make emptying easy
  • Built-in ergonomic handholds help you tumble the compost without any fuss
  • Dual chamber allows for uninterrupted production; can cook 2 compost batches at once
  • UV-protected plastic and galvanized steel construction is made to last


  • Does not have a locking feature for holding the chambers in place
  • Assembly is tedious and takes a couple of hours plus a helper to complete

Get the FCMP Outdoor IM4000 dual-chamber tumbling composter at:

What is the FCMP Outdoor IM4000 dual-chamber tumbling composter?

The FCMP Outdoor tumbling composter is a large 37-gallon composting container that allows you to make two sets of compost simultaneously: a “finished” set of compost and one in progress. It’s BPA-free, designed for outdoor use, and made from post-consumer plastic with a UV inhibitor to prevent fading from sunlight.

The FCMP Outdoor tumbling composter stands 36 inches tall and has a ground clearance of 13.5 inches. It’s higher off the ground than other dual-chamber composters in the same price range, which makes it easier to empty.

This dual-chamber unit is 30 inches long and 28 inches wide, so while it is a larger composter, I found it was still compact enough to place next to my garden, outside my home, or next to my shed without being much of an eyesore.

A person emptying compost from the FCMP Outdoor tumbling composter
Photo: Jenn Ryan for Bob Vila

Is the FCMP Outdoor tumbling composter easy to assemble?

I found the assembly process to be one of the most challenging parts of using this product. While it’s not particularly difficult, it is very tedious. The chamber alone has 56 bolts that must be screwed into place. Although the instruction manual says that they can be twisted into place using a flathead screwdriver and an adjustable wrench, I found it was easier with a squarehead screwdriver and a 10mm socket wrench. It does not come with any tools for assembly.

I assembled the FCMP Outdoor tumbling composter with the help of my husband. It’s easier with two people because one can hold the sections of the chamber in place while the other screws in the bolts.

Since we’ve assembled this particular composter before and didn’t need much guidance, we exclusively used the paper instructions. If you run into trouble putting the FCMP Outdoor composter together, search “FCMP Outdoor tumbling composter assembly,” and you will find several instructional videos that may be easier to follow than the user manual.

Is the FCMP Outdoor tumbling composter easy to use?

Once assembled, the FCMP Outdoor tumbling composter is easy to use. The first step is adding food scraps and dry material (a mix of dry grass, hay, and leaves) to one side. When that side is full and ready to “cook,” you simply slide the door over to reveal the empty chamber, where you can add additional fresh scraps and dry material.

You must then turn the composter every 2 or 3 days to mix the compost and encourage proper cooking. Tumbling the cooking compost is easy using the built-in handholds, which double as fins that extend into the chamber to help mix and break up the material.

Aeration is another essential part of composting, and the FCMP Outdoor composter has air vents on its sides to help with the process. In general, keeping the vents open exposes the compost to oxygen and helps dry it out, and closing the vents helps the mix retain more moisture. Adjusting the ratio of oxygen and moisture in the composting environment allows you to get better-quality compost quickly. Too much moisture can cause the compost to clump together and putrefy, while making it too dry will slow the cooking process.

Another nice aspect of the FCMP Outdoor composter is its ground clearance, which is high enough that you can use a variety of receptacles when emptying the cooked compost. When using composters that sit lower to the ground, I have been limited to emptying the compost onto a tarp or even a winter sled. With the FCMP Outdoor tumbling composter, I used a short bucket that was convenient to carry to the garden.

It’s important to note that this composter doesn’t have locking mechanisms on the frame, so I had to hold the chamber in place when emptying it. Also, since the door on the composter is a single piece, I had to slide it open rather than simply remove one side. You can’t do this until you’re already holding the composter upside down for emptying, which makes it a challenge. If the door was split into two removable sides or the frame had a locking mechanism, emptying would be a bit easier.

The FCMP Outdoor tumbling composter partially set up to show capacity and internal design
Photo: Jenn Ryan for Bob Vila

Is the FCMP Outdoor tumbling composter good for quick composting?

FCMP Outdoor claims the composter can create compost in as little as 2 weeks. I found that to be a pretty tight timeline, although I did test it in the middle of summer on the East Coast, where temperatures were very hot with high humidity. In my tests, 1 month was a more realistic timeline for using this dual-chambered composter to create high-quality compost ready to nourish plants.

How durable is the FCMP Outdoor tumbling composter?

I have tested the FCMP Outdoor composter multiple times—sometimes for months on end—and never noticed any deterioration. Its durable construction held up without fail when sitting outside through several seasons in very hot temperatures as well as freezing ones.

The composter’s frame is galvanized steel, which is designed to last without issue. Galvanized steel takes a very long time to rust—several decades in some areas.

The body of the composter is made from BPA-free, 100 percent post-consumer recycled plastic. It’s also UV-inhibited, meaning it contains a protective additive to prevent degradation and fading due to the sun. I have not seen any fading or durability issues during any of my tests of this product.

Is the FCMP Outdoor IM4000 dual-chamber tumbling composter worth the money?

For its size, the FCMP Outdoor dual-chamber tumbling composter is one of the less expensive composters on the market. At under $100, I definitely think it’s a good value.

Since the composter requires virtually no maintenance (unless you want to rinse it out between compost batches), it’s good to go once assembled. And because it’s made with durable, UV-inhibited plastic and galvanized steel, it’s designed to last a long time, even with regular use.

The composter makes 5 cubic feet of compost with both chambers, which is enough to cover about 1,620 square feet of garden space with compost that’s 1 inch thick. That’s enough for a small to medium garden, but if you don’t have a plot that big or don’t want extra for your landscaping or indoor plants, a smaller chamber may be better for your needs.

A close-up of the stand and handles on the FCMP Outdoor tumbling composter
Photo: Jenn Ryan for Bob Vila

Should you buy the FCMP Outdoor tumbling composter?

Although this is not my favorite dual-chambered composter, it is a good option for the price, especially given its quality and durability. If you’re looking for a larger composter or one with more features, I’ve tested those, too.

The FCMP Outdoor composter will meet many gardeners’ needs—it’s not too large or too small. It doesn’t stick out in the yard the way a 50- or 100-gallon composter would, and its more- compact size means it can be placed virtually anywhere.

For those who have small or medium-size gardens or are new to composting, this conveniently sized dual-chamber composter is a worthy consideration for the price. Although assembly can be tedious and time-consuming, once the product is assembled, it requires no maintenance and can be used for years without issue.

Where to Buy the FCMP Outdoor IM4000 Dual-Chamber Tumbling Composter

Get the FCMP Outdoor IM4000 dual-chamber tumbling composter at:

Meet the Tester

Jenn Ryan is a gardening enthusiast who has been writing for since 2020. She has tested several of the top outdoor composters and has been composting since 2016, and she has experience with everything from a large compost pile to many different large and small composter products. She takes a detailed and practical approach to writing product reviews based on daily experience with the product.

Jenn Ryan Avatar

Jenn Ryan

Contributing Writer

Since 2015, Jenn Ryan has been a freelance writer with a focus on natural health, eco-friendly products, and wellness. She’s been writing for since 2020 and covers natural alternatives to conventional products, solar solutions, and environmental topics.