How Automatic Composters Work: A Beginner’s Guide to Composting at Home

Make Less Waste. Compost More Easily. Live Sustainably.

You know you should probably compost. You’ve heard that food scraps don’t belong in the trash, and you like the idea of turning kitchen waste into something useful. But then reality sets in: Where do you put the scraps? What exactly goes into a compost bin? And do you really want to manage a pile of decomposing food in your backyard?

This is where automatic composters come in.

Unlike traditional composting, which can take weeks or months and requires the right balance of materials, automatic composters use heat, airflow, mixing, and other processes to break down food scraps much faster. They can make composting more convenient, especially for people living in apartments, small homes, or places without outdoor space.

But how do they actually work? Are they really composting machines or are they just fancy food-waste processors?

1.What is an Automatic Composter?

An automatic composter is an electric appliance designed to process food scraps inside a contained chamber.

Instead of putting your food waste into an outdoor pile and waiting for microorganisms to naturally break it down, the machine creates controlled conditions that speed up the process.

Depending on the model, an automatic composter may use:

• Heat
• Mixing or grinding
• Air circulation
• Moisture control
• Microorganism or enzymes
• Filtration systems to reduce odors

The exact process varies between machines so not every automatic composter produces the same type of finished material.

Some machines reduce food scraps into a dry, soil-like material in a matter of hours. Others use a longer biological process that more closely resembles traditional composting.

2. How Does an Automatic Composter Work?

The idea is fairly simple. You put food scraps into the machine, close the lid, and select a cycle. The machine then creates the conditions necessary to help break down the material.

A typical process may look like this:

Step 1: Add the food scraps into the machine

Step 2: The machine processes the waste by using heat, mixing, grinding, or aerating the food scraps.

Step 3: Moisture is removed from the food scraps

Step 4: You collect the output

Depending on the machine, the output may be called compost, dehydrated food waster, compost material, or something similar.

3. Is the Output from an Automatic Composter Actually Compost?

Automatic composters don’t necessarily create compost. It depends which product you will use.

Traditional composting relies heavily on biological decomposition. Microorganisms gradually break down organic materials under specific conditions until they become stable compost.

Some automatic machines primarily dehydrate and grind food scraps. The resulting material may look like soil or compost, but it hasn’t necessarily gone through the same biological process as mature compost.

Other systems incorporate microorganisms and additional processing designed to continue decomposition.

4. Automatic Composters vs. Traditional Composting

Why would someone choose an automatic composter instead of a traditional compost bin?

It mostly comes down to convenience and space.

Traditional composting can be inexpensive and environmentally effective, but it requires the right conditions and some ongoing management.

You may need to: 

• Balance “green” and “brown” materials
• Maintain moisture
• Turn the pile
• Give the pile enough airflow
• Manage odors and pests
• Wait for the compost to mature

Automatic composters simplify some of these steps.

One is not necessarily “better” than the other.

The best choice depends on your home, budget, available space and how much effort you’re willing to put into composting.

5. Do Automatic Composters Smell?

One major reason people avoid composting is the fear that their kitchen will start smelling like a garbage truck.

Automatic composters are designed to reduce this problem.

Many models use enclosed chambers and filters to control odors during processing. Some use activated carbon filters or similar systems to help capture unpleasant smells.

6. Are Automatic Composters Worth It?

The answer depends on what you’re trying to solve.

An automatic composter may be worth considering if you:

• Live in an apartment
• Don’t have outdoor space
• Produce a lot of food scraps
• Want a low-maintenance way to process food waste
• Are willing to pay for convenience

It may not be worth investing in if you:

• Already have an effective backyard compost system
• Produce very little food waste
• Don’t want another appliance using electricity
• Are looking for completely hands-off composting

7. How to Get Better Results From an Automatic Composter

Once you have a machine, a few simple habits can make the experience easier:

• Follow the capacity limits
• Chop large pieces
• Don’t add restricted materials
• Clean it regularly
• Maintain filters
• Use the output correctly

8. How Do Different Automatic Composters Compare?

Automatic composters are not created equal.

Some machines primarily heat, dry, and grind food scraps, reducing them into dry material that takes up much less space. Others use microorganisms to biologically break down food waste over a longer period.

It’s important to understand the difference as the machine you choose decides what happens to your food waste, what you can put inside it, how often you need to empty it, and what you can ultimately do with the output.

Here are four popular options to compare: Reencle Gravity, Lomi 3, FoodCycler Eco 5, and Mill Food Recycler.

Reencle Prime: Microbial Composting

Reencle takes a different approach from many countertop food recyclers. It uses microorganisms, heat, and aeration to biologically break down food waste inside the machine.

Reencle Prime has a 14-liter internal volume and can process up to 2.2 pounds of food waste per day and only needs to be emptied once every 3-4 weeks or whenever the dirt reaches the internal max line. The manufacturer says its filter lasts approximately 9-12 months, and the microbes reproduce naturally, so regular purchases of microbial starter aren’t required.

One of Reencle’s biggest advantages is the range of food it can handle. According to its materials guide, it can process common fruit and vegetable scraps, citrus, meat, seafood, dairy, cooked food, and coffee grounds. However, bones, large pits, non-food materials, yard waste, chemicals, cleaning products, medications, and pet waste should not be added.

The trade-off is time. Unlike a dehydrator-style machine that can produce a dry output within hours, Reencle’s biological process takes longer, and its output benefits from additional curing before being used directly with plants.

Best for: People who want an indoor system that gets closer to traditional biological composting without maintaining an outdoor pile.

Lomi 3: Compact Food Recycler

Lomi 3 is designed to make food-waste processing easy in a kitchen-sized appliance. It has a 3-liter bucket, smaller than previous Lomi models, and can process food scraps including fruits, vegetables, meats, dairy, breads, grains, and some yard waste. Depending on what mode you choose, a cycle takes anywhere from 3-20 hours and uses up to 1.0 kWH of electricity.

Lomi also has specific rules around what goes inside. For example, fruits peels and citrus can be processed but it is recommended to limit high-sugar fruits as this will cause the bottom of the mixture to harden. Meat and dairy can also be processed but they should be added in moderation. Hard bones and seafood shells should be avoided because they can damage the grinder.

Lomi requires carbon-filter replacements every three months or 45 cycles. A single filter refill is currently listed at $29.99, although subscription pricing is also available.

Best for: People who want a compact, convenient countertop food recycler and don't mind producing a processed food-waste material rather than traditional compost.

FoodCycler Eco 5: High-Capacity Food Recycler

FoodCycler Eco 5 is another heat-and-grind style food recycler. It is better suited to larger households or people who generate a lot of food scraps as it has a 5-liter bucket.

A typical cycle takes approximately 4-9 hours and uses about 1.5 kWh of electricity per cycle.

It can process a particularly broad range of food scraps, including fruit and vegetable scraps, meat, fish, poultry, eggshells, shellfish, coffee grounds, and poultry and fish bones. The manufacturer does caution you about which bones to process. Smaller, softer bones such as fish and poultry are safe for processing while larger bones such as pork and lamb should only be in small amounts. Avoid large bones, excess oils, candy, gum, and most compostable plastics.

The carbon filters generally last around 3-4 months with regular use, although actual life depends on the type and amount of food being processed.

Best for: Larger households that want to process a lot of food waste quickly and don't necessarily need the machine itself to produce finished compost.

Mill Food Recycler: Large-Capacity, Low-Maintenance Option

Mill takes the food -recycler approach even further. It has a 6.5-liter capacity and can hold up to approximately 40 pounds of food scraps. 

Mill automatically decides when and how long to run based on what you add– most cycles typically take 3-8 hours. It uses approximately 0.7 kWh of electricity per day on average, although actual usage varies depending on how much food is added and how wet it is. Like other automatic composters, the Mill can process small bones like chicken and fish, but it cannot handle large, dense bones.

The carbon filter needs to be replaced every 5-6 months for the Mill Essential and 10-12 months for the Mill Plus.

The biggest downside is the price. Mill Essential starts at about $999 and the Mill Plus starts at $1,149, making it considerably more expensive than the other popular automatic composters in this comparison.

Best for: Households that generate a large amount of food waste and prioritize automation, capacity, and minimal day-to-day maintenance.

Which one is best?

There isn’t one automatic composter that is best for everyone. It depends on what you’re looking for.

If your priority is actually biologically processing food waste into compost-like material, Reencle is the most distinct option for this group.

If your priority is quickly reducing the volume of food waste, Lomi and FoodCycler are more straightforward food-recycling options.

The important thing is to compare the machines based on what you want the output to become, not just how quickly the machine makes your food scraps disappear.

Overall, Reencle prime is the standout product due to its distinct feature of microbial decomposition producing real compost rather than simply drying and grinding food waste. However, FoodCyler, Lomi, or Mill is a better product if your main goal is rapid volume reduction, larger capacity, or maximum automation.

What Really Matters

Automatic composters aren’t magic machines, but they can make managing food waste a whole lot easier, especially if traditional composting isn’t practical for you.

The biggest benefit isn’t perfect compost. It’s making a sustainable habit that's easier to maintain. A simple system you use will always beat a complicated one you abandon.

Whether you choose automatic composting or traditional composting, the goal is the same: find a practical way to make better choices more often.

Sustainability doesn’t have to be complicated to count.