How Long Does It Take Clothes to Decompose?

Clothes made from natural fibers like cotton and linen can decompose in as little as a few weeks under favorable conditions, while synthetic fabrics like polyester show essentially zero biodegradation even after years. The real answer depends heavily on the fiber type, the chemical treatments applied to the fabric, and the environment where the garment ends up. A cotton t-shirt composted in moist, microbe-rich soil is a fundamentally different proposition from that same shirt buried in a sealed landfill, and both are worlds apart from a polyester jacket tossed in the ocean.

Cotton, Linen, and Other Plant-Based Fibers

Plant-based cellulosic fibers are the fastest to break down. Cotton and flax (the plant behind linen) decompose more readily than any other common textile fiber because soil bacteria and fungi already produce the enzymes needed to digest cellulose. In laboratory anaerobic digestion experiments, most textile wastes made from natural fibers visibly fragmented from intact fabric into small pieces within 18 days, with flax producing the highest methane yield, a sign of thorough microbial breakdown.¹ In seawater tests off the coast of La Jolla, California, wood-based cellulose fabrics fell apart within 30 days.² A separate marine study found that natural and regenerated cellulose fibers underwent complete biodegradation within roughly 35 days.³

Those timelines reflect relatively ideal conditions: warm temperatures, moisture, oxygen (or active anaerobic microbial communities), and direct contact with microorganisms. In a backyard compost pile that is kept warm and turned regularly, an untreated cotton garment can largely disintegrate within a few months. In a dry attic or sealed plastic bag, that same garment could last decades because the microbes simply cannot get to work.

Wool, Silk, and Other Animal Fibers

Animal-based protein fibers also biodegrade, but they are slower than cotton and linen. Wool is particularly resistant because its outer cuticle layer acts like a set of overlapping scales that physically block microbial access. Researchers in China isolated a wool-degrading bacterium that could strip the cuticle layer from wool fibers completely within 48 hours under controlled conditions, but that required a specialized enzyme (keratinase) that most soil bacteria don’t produce in large quantities.⁴ In a standard compost setting, wool breaks down over several months to a year or more, depending on temperature and microbial activity.

Silk, despite also being a protein fiber, degrades faster than wool. Its chemical structure is simpler, lacking wool’s tough cuticle armor.⁵ Under composting conditions, silk fabric may lose structural integrity in a matter of weeks, behaving more like a cellulosic fiber than a typical protein one. For practical purposes, if you are composting old clothes, silk is closer to cotton on the decomposition timeline and wool is the slowpoke of the natural fiber group.

Polyester, Nylon, and Other Synthetics

Synthetic fibers are where the decomposition story takes a hard turn. Polyester (polyethylene terephthalate, or PET), nylon, and acrylic are all derived from petroleum, and microorganisms in nature have had very little evolutionary time to develop enzymes that can break them down. Under standardized composting tests, polyester, nylon, and acrylic showed no measurable biodegradation at all.⁶ Pure PET fibers do not biodegrade within the timeline of any standardized testing method currently in use.⁷

In the ocean, the picture is just as bleak. While cellulose fabrics disintegrated within about a month, polyester fabrics remained relatively intact with only a limited biofilm after more than 200 days submerged in seawater.² The common estimate you see floating around the internet is that polyester takes “200 years” or “up to 200 years” to decompose. The honest answer is that nobody really knows, because nobody has run a 200-year experiment. What research confirms is that polyester shows no meaningful breakdown over the timescales scientists have tested, and extrapolations from those studies point to centuries or longer in real-world conditions.

Why Chemical Treatments Slow Things Down

Even a garment made entirely from cotton is not just cotton by the time it reaches your closet. Most textiles are treated with dyes, wrinkle-resistant finishes, water-repellent coatings, or flame retardants. These chemical treatments affect how quickly microbes can get to the underlying fiber.

A study testing various cotton finishes found that durable-press and water-repellent treatments slowed the initial rate of biodegradation. The finishes essentially formed a barrier that blocked the enzymes microorganisms secrete to digest cellulose. The encouraging finding, though, was that all the treated cotton samples still reached more than 60 percent biodegradation within 102 days. The finishes delayed the start of the process rather than preventing it entirely.⁸ So your wrinkle-free cotton shirt will still decompose; it just takes longer to get started than an untreated fabric would.

Dyes are a mixed bag. Some dyes had little effect on decomposition, while others measurably slowed it. The overall trend matched what researchers saw with finishes: the rate changed but the end result was similar, because the underlying cellulose remained accessible once the surface treatment wore away. For blended fabrics that combine cotton with polyester, however, the synthetic component never goes away. The cotton fraction will break down and the polyester fraction will persist, leaving behind a web of synthetic microfibers.

How the Surrounding Environment Changes Everything

A garment’s decomposition timeline depends as much on where it ends up as on what it is made of. The same cotton shirt could break down in weeks in warm compost, months in a landfill, or only partially in cold dry soil over years. Here is why.

Active compost: Warm (above roughly 55°C in a hot pile), moist, oxygen-rich, and teeming with bacteria and fungi. This is the fastest decomposition environment for natural fibers. Cellulosic fabrics can lose structural integrity in weeks.
Soil burial: Slower than compost because soil temperatures are lower and microbial density varies. A cotton garment buried in topsoil in a temperate climate might take several months to a year to significantly degrade.
Seawater: Natural cellulose fabrics break down within about a month in coastal seawater. Synthetic fabrics show essentially no breakdown over the same period.
Landfill: The most common destination for discarded clothes, and one of the worst for decomposition. Modern landfills are designed to entomb waste, not break it down. Once buried under layers of compacted trash and sealed from air and moisture, even natural fibers decompose extremely slowly.

The landfill environment deserves its own closer look, because that is where the vast majority of discarded clothing actually goes.

What Really Happens to Clothes in a Landfill

Roughly three-quarters of all textile waste worldwide ends up in landfills.⁹ That is a staggering figure given that textiles are almost entirely recyclable in theory. In practice, mixed-fiber garments, zippers, buttons, and chemical treatments make recycling difficult and expensive, so most clothes go straight into the ground.

Once there, conditions are nothing like a compost pile. Landfills are anaerobic (oxygen-starved) and often dry. The bacteria that work fastest on cellulose are aerobic, so their activity is limited. Anaerobic bacteria can still break down natural fibers, but far more slowly, and they produce methane as a byproduct, a potent greenhouse gas. Blue denim is a notable holdout even under anaerobic conditions. In one experiment that fragmented most natural textiles within 18 days, denim resisted breakdown, likely because of its heavy weave and the indigo dye treatment.¹

Landfill decomposition also creates a chemical problem. As clothing breaks down, the chemicals embedded in it leach out. Research using model landfill reactors found that clothing released per- and polyfluoroalkyl substances (PFAS) into the surrounding leachate over the course of about 500 days, with most of the release not occurring until after day 100. The dominant chemical released was PFOA, a long-lived environmental contaminant.¹⁰ PFAS compounds are sometimes called “forever chemicals” because they resist breakdown in the environment. So even when a garment decomposes, it can leave behind pollutants that outlast the fabric itself.

The Microfiber Problem Outlasts the Garment

Decomposition is not the only way clothes release material into the environment. Every time you wash synthetic clothing, tiny fibers shed from the fabric and flow into wastewater. Many of these microfibers are too small for water treatment plants to capture, and a significant portion ends up in agricultural soil through the application of treated sewage sludge as fertilizer.

These synthetic microfibers do not biodegrade once they reach the soil. Research has shown that high concentrations of microplastics in soil can cause intestinal damage and reduced appetite in earthworms and springtails. The microfibers alter gut microbiomes in these soil invertebrates, decreasing beneficial bacteria and increasing bacteria associated with inflammatory stress.¹¹ Microplastics in soil also reduce its water-holding capacity, which can inhibit plant root growth over time.¹²

This means the environmental footprint of a polyester garment extends well beyond the garment’s visible lifespan. The shirt may look fine for years in your closet, but it has been shedding invisible fibers into waterways with every wash cycle, fibers that will persist in the environment for decades or centuries after the shirt itself is thrown away.

Do “Biodegradable” Synthetics Actually Decompose?

Polylactic acid (PLA) is often marketed as a biodegradable alternative to conventional polyester. It is derived from plant starches rather than petroleum, which sounds promising. But the reality in most natural environments is disappointing. In marine water testing, PLA textiles showed no degradation for over 428 days, performing no better than conventional polyester or polypropylene over that period.³

PLA does biodegrade, but only under specific industrial composting conditions: sustained temperatures above 58°C, high humidity, and specialized microbial communities. Those conditions are not found in a backyard compost bin, a landfill, or the ocean. So calling PLA clothing “biodegradable” without qualification is misleading. If that garment ends up in the ocean or a landfill, it behaves just like conventional plastic. Researchers are investigating other bio-based polymers with better biodegradation profiles, including materials with antibacterial properties and reasonable mechanical strength for textile use.¹³ But for now, no commercially available synthetic textile fiber reliably breaks down in the environments where clothes actually end up.

Blended Fabrics and the Recycling Problem

Most clothing sold today is not made from a single fiber. A typical t-shirt might be 60 percent cotton and 40 percent polyester. A pair of jeans might include spandex for stretch. These blends create a decomposition paradox: the natural fiber fraction will eventually break down, but the synthetic fraction will not, leaving behind a skeleton of persistent microfibers in whatever environment the garment was discarded.

Blends also create serious obstacles for recycling. Mechanical recycling can recover a large share of fiber mass (one analysis found an average of 86 percent recovery), but the resulting fibers are weaker and typically need to be blended with virgin material to be usable.¹⁴ Chemical recycling techniques that separate cotton from polyester at the molecular level are being developed, but they remain expensive and are not yet widespread. The practical result is that most blended garments are neither effectively recyclable nor fully biodegradable.

Engineered Enzymes and the Future of Textile Breakdown

The fact that standard synthetics resist all biodegradation has pushed researchers toward a different approach: engineering enzymes that can break them down artificially. Recent work on PET-digesting enzymes has achieved higher recycling efficiency for polyester polymer than for cellulosic materials, an inversion of what happens in nature.⁷ These enzymes break the polymer chains of PET into their chemical building blocks, which can then be reassembled into new polyester. It is not decomposition in the traditional sense, but it achieves the same practical goal of eliminating persistent textile waste.

For wool, keratinase-producing bacteria can strip the protective cuticle that normally slows decomposition, potentially opening the fiber to much faster breakdown.⁴ These biological tools are still largely confined to laboratories and pilot plants. Scaling them up to handle the volume of textile waste generated globally is a formidable engineering challenge. But the trajectory is clear: biology alone will not solve the synthetic textile problem, so researchers are building the biological tools that nature has not had time to evolve.

Quick Reference by Fiber Type

Because decomposition times vary so widely by both material and conditions, here is a practical summary of what current research supports. These ranges assume reasonably active biological conditions, not a sealed landfill where everything slows down dramatically.

Cotton (untreated): A few weeks in active compost or warm seawater; a few months in soil; years in a landfill.
Linen (flax): Similar to cotton, often slightly faster. Among the fastest natural fibers to decompose.
Silk: Weeks to a few months under composting conditions, faster than wool due to its simpler protein structure.
Wool: Several months to over a year in compost; slower in soil. The cuticle layer acts as a natural barrier to microbial attack.
Cotton with finishes: Slower to start than untreated cotton, but still reaches substantial biodegradation within a few months in active biological environments.
Polyester, nylon, acrylic: No measurable biodegradation under any standard test condition. Estimated persistence of centuries or more in the environment.
PLA (“biodegradable” plastic): Degrades under industrial composting conditions (high heat, humidity) but shows no breakdown for over a year in seawater and performs like conventional plastic in most real-world disposal scenarios.
Blends (cotton-polyester): The cotton fraction decomposes; the polyester fraction persists indefinitely as microfibers.

Denim as a Special Case

Jeans deserve a specific mention because they are one of the most common garments people wonder about, and they behave somewhat unusually. Denim is cotton, so in principle it should decompose like other cellulosic fabrics. But in the anaerobic digestion study noted earlier, blue denim was the one natural textile that did not obviously fragment within 18 days alongside the others.¹ The likely reasons are its heavy, tightly woven construction and the indigo dye, which together make it harder for bacteria to penetrate. In a compost pile, jeans will still break down, but expect them to take considerably longer than a thin cotton shirt, possibly a year or more depending on conditions. Shredding or cutting old jeans before composting speeds the process significantly by increasing the surface area available to microbes.

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