Elastane, sold as spandex in the US and as Lycra under its best-known brand name, is a synthetic elastomeric fibre blended into fabric in small percentages to give stretch and recovery. It appears in denim, activewear, swimwear, hosiery and most modern knitwear. The carbon footprint of elastane averages 5.80 kg CO₂e per kg of fibre, around 21% above polyester. In fabric it moves the finished figure by about 1% either way, up against a cotton base and down against a nylon one, which is not where its real cost sits.
What are the CO₂e emissions of elastane?
5.80 kg CO₂e per kg of elastane fibre
~ 21% above polyester
2.7 times global-average cotton
The figure covers cradle-to-gate production, which includes the petrochemical feedstock, polymerisation into the elastomer, and spinning into filament. It stops at fibre ready to blend.
Elastane is a polyurethane-based polymer. The chemistry is more involved and the yields lower, so per kilogram it costs more carbon than the base fibres it is usually blended into.
How does elastane compare to other fibres?
| Fibre | kg CO₂e per kg |
|---|---|
| Cotton, global average | 2.13 |
| Polyester | 4.78 |
| Elastane | 5.80 |
| Nylon | 9.28 |
Elastane water use
Elastane uses 0.03 m³ of water per kg of fibre, effectively the same as polyester at 0.03 and far below cotton at 0.75.
As a synthetic fibre with no agricultural stage, elastane’s water figure is low and unremarkable.
What elastane means for a product footprint
A 200 gram garment at 5% elastane content, blended with cotton:
| Component | Weight | Fibre-stage emissions |
|---|---|---|
| Elastane | 10 g | 0.06 kg CO₂e |
| Cotton | 190 g | 0.41 kg CO₂e |
Elastane accounts for about 13% of that garment’s fibre-stage carbon while making up 5% of its weight.
Swimwear and performance base layers run 15 to 20% elastane, and at 20% in a 200 gram polyester-based garment the elastane contributes 0.23 kg CO₂e against 0.76 for the polyester, which is roughly 23% of the fibre stage.
Elastane fabric carbon footprint
Elastane is never a fabric by itself. It goes into a base fibre.
Cotton jersey, 5% elastane: 14.49 kg CO₂e per kg
Polyester activewear knit, 18% elastane: 16.85 kg CO₂e per kg
Nylon swim knit, 20% elastane: 23.50 kg CO₂e per kg
The cotton jersey, built out:
| Stage | kg CO₂e per kg |
|---|---|
| Cotton and elastane fibre, 95/5 | 2.32 |
| Ring-spun yarn | 2.41 |
| Circular knitting | 6.97 |
| Scouring and bleaching | 0.30 |
| Vat dyeing | 2.36 |
| Finishing | 0.13 |
| Knit fabric | 14.49 |
The other two run through the same stages, with disperse dyeing for the polyester and acid dyeing for the nylon.
What the elastane is actually costing
Run the same three fabrics without it:
| Fabric | With elastane | Without | Difference |
|---|---|---|---|
| Cotton jersey, 5% | 14.49 | 14.30 | +1.3% |
| Polyester activewear knit, 18% | 16.85 | 16.67 | +1.1% |
| Nylon swim knit, 20% | 23.50 | 24.20 | −2.9% |
Elastane at 5.80 is lower than nylon at 9.28, so every kilogram of nylon it displaces brings the fabric figure down rather than up. A 20% elastane swim knit comes in around 3% below the same fabric in nylon alone.
That is not what most people expect, and it does not make elastane a low-carbon choice. It is arithmetic on two fibre figures, and it only holds where the base fibre costs more than elastane does. Against cotton, elastane adds. Against nylon, it subtracts.
None of the three include heat setting, which stretch fabrics need and which has no figure here. Expect real numbers to sit above all three, by more at the higher loadings.
We calculate these totals on the following construction: ring-spun yarn, batch dyeing and a light finish. A different spinning system, dye class or finishing route moves the number. Heavier finishing adds more than the figure above allows for, and the loss between fibre bought and fabric delivered is not counted, so treat these as a floor rather than a ceiling.
The end-of-life cost is the larger one
A cradle-to-gate figure says nothing about what elastane does to a garment’s recyclability, and that is where the material decision actually bites.
Mechanical fibre-to-fibre recycling needs a reasonably clean input stream. Elastane blended through a cotton or polyester fabric cannot be separated mechanically, and its presence above a few percent is enough to make a garment unsuitable for most current recycling routes. The garment goes to landfill or incineration instead.
In landfill, elastane carries 1.65 kg CO₂e per kg under uncategorised conditions, rising to 2.72 where the site is managed. Those figures apply to the whole garment once it is unrecyclable, not only to the elastane fraction.
So the useful question is not what 10 grams of elastane emits at the fibre stage. It is whether adding it moves 200 grams of garment from a recycling route to a disposal route.
Where the product allows it, mechanical stretch through knit construction delivers recovery without elastane. Where it does not, specifying the lowest loading the product needs is the meaningful lever, because the difference between 2% and 5% is negligible in fibre carbon and can be decisive for recyclability.
What these figures cover
Fibre stage, with three fabric-level calculations. The 5.80 figure covers feedstock through to spun filament. The three stretch fabrics add spinning, knitting, preparation, dyeing and finishing. Heat setting, which every stretch fabric needs, is in none of them. Garment making and use phase are separate again.
Industry averages. These figures support an estimate of your elastane contribution. They cannot support a supplier comparison.
One figure, no regional split. It applies to elastane from any origin.
No recycled or bio-based variant. Neither is available, and substituting a recycled polyester figure would not be defensible.
Carbon and water only. Microfibre release, which is a live concern for stretch synthetics, is not represented.
