How We Score Sustainability
You've probably seen sustainability scores before. A brand gets a "B+" or a material is labelled "eco-friendly." But what does that actually mean? Who decides? And why should you trust it?
We built the Fashion Sustainability Index because we were asking the same questions. We wanted a tool that would give us real answers, not marketing spin.
Here's exactly how our scoring works.
The Short Version
We assess two main things when you use our calculator:
Materials
What's the garment made from?
Brand
Who made it and how transparent are they?
Each receives a score from 0-100 based on environmental and ethical research. The more information you provide, the more accurate your result.
What We Measure (And Why)
Materials: The Biggest Impact
The fabric in your clothes accounts for the majority of their environmental footprint. Growing cotton, raising sheep, producing polyester. This is where the emissions, water use, and pollution happen.
We assess materials across five criteria:
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Carbon Footprint: How much greenhouse gas is released to produce one kilogram of this material? We look at farming, processing, and manufacturing emissions. Recycled materials typically score highest here because they skip the raw material extraction phase.
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Water Consumption: Fashion uses an enormous amount of water—for irrigation, processing, and dyeing. But not all water use is equal. We distinguish between rainfall (renewable), extracted groundwater (scarce), and polluted wastewater (harmful). A material that uses mostly rainfall scores differently than one requiring heavy irrigation in water-stressed regions.
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Pollution Impact: Does production contaminate waterways? Are pesticides involved? Does dyeing release harmful chemicals? We assess the pollution profile across the material's lifecycle.
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Chemical Safety: What chemicals are used in production, and how are they managed? Materials produced with minimal chemical inputs, or with closed-loop systems that recover solvents, score higher.
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End of Life: What happens when you're done with the garment? Natural fibres biodegrade. Synthetics persist for centuries. This matters for long-term environmental impact—though production still accounts for the lion's share.
Why these five? Because they represent the most significant environmental impacts of textile production, according to Life Cycle Assessment research. We weight them based on urgency and magnitude. Climate change and water scarcity are weighted slightly higher because they're the most pressing global challenges.
Brands: Accountability Matters
A recycled cotton t-shirt from a transparent, ethical brand is different from the same material from a company with documented labour violations.
We assess brands across four criteria:
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Transparency: Do they publish their supplier list? Do they disclose factory locations? Transparency enables accountability. Without it, other claims are unverifiable.
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Labour Practices: Are workers paid fairly? Are factories safe? Has the brand committed to living wages? We look at third-party audits, certifications, and documented practices.
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Environmental Initiatives: What's the brand doing about climate change? Do they have measurable targets? Are they making progress? Vague commitments count for less than verified action.
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Certifications: Has the brand earned credible third-party certifications? B-Corp, Fair Trade, and similar credentials add weight. They're harder to fake than marketing claims.
Why these four? Because sustainability isn't just environmental. The fashion industry employs over 75 million people worldwide, many in vulnerable conditions. A truly sustainable brand addresses both planetary and human impact.
How We Combine the Scores
When you use our calculator, we combine whatever information you provide:
The more data you provide, the more accurate your result. We show you the confidence level so you know what the score represents.
Missing information doesn't penalise your score, it just reduces accuracy. We'd rather give you a useful estimate than refuse to calculate because you don't know where something was made.
Our Data Sources
Every score in our database is backed by research. We prioritise:
Tier 1: Peer-reviewed research Academic studies using Life Cycle Assessment (LCA) methodology, published in scientific journals and following ISO standards.
Tier 2: Industry databases Established databases like the Higg Materials Sustainability Index and Textile Exchange reports, used across the fashion industry.
Tier 3: Certification bodies Data from organisations like GOTS, GRS, Fair Trade, and B-Corp. Bodies with rigorous verification processes.
Tier 4: Verified corporate data Brand sustainability reports, where claims can be cross-referenced against third-party audits.
We require multiple sources for each data point and note when research is limited or contested. Transparency about uncertainty is part of our commitment to honesty.
What We Don't Do
We don't accept payment for scores. Brands can't pay to improve their rating. Our assessments are independent.
We don't simplify to the point of misleading. Some things are complicated. We'd rather explain nuance than pretend it doesn't exist.
We don't pretend certainty where there isn't any. If data is limited, we say so. If research disagrees, we acknowledge it.
Our confidence ratings reflect actual data quality.
We don't guilt-trip. Our goal is to inform, not shame. We show you better alternatives without judging your current choices.
Limitations: What We Can't Tell You
We assess categories, not individual products. "Organic cotton" scores the same whether it's a well-made garment or a poorly constructed one. Quality and durability aren't captured in material scores.
We rely on available data. Some materials have extensive research; others have less. We're transparent about confidence levels, but we can't score what hasn't been studied.
Production varies within categories. "Made in China" covers factories with vastly different practices. Regional scores are averages, not guarantees about specific suppliers.
Use phase isn't included. How you care for clothes (washing, drying) affects their total footprint. Our scores cover production, not ownership.
Sustainability is complex. A single number can't capture everything. Our scores are a useful starting point, not the final word.
Why Trust Us?
We built this tool because we needed it ourselves. We wanted to make sustainable choices but found most information either too vague ("eco-friendly!"), too complicated (academic papers), or too biased (brand marketing).
Our approach:
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Research-based: Every score traces back to credible sources
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Transparent: We explain our methodology (you're reading it)
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Honest: We acknowledge limitations and uncertainty
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Independent: No brand partnerships, no paid placements
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Practical: We give you actionable information, not just data
We update our database as new research emerges and acknowledge when our methodology improves. This is version 1.0. We'll keep refining it.
Frequently asked questions
Keep Reading
Explore materials in our database: [Browse All Materials →]
Learn about textile certifications: [Certifications Explained →]
Try the calculator yourself: [Calculate Your Garment's Score →]
Our Commitment
We believe informed consumers make better choices. Better choices create market demand for sustainable products. Market demand drives industry change. That's why we built this tool and why we made it free.
Sustainability shouldn't require a PhD to understand. Our job is to translate the research into something you can actually use and to do it honestly.
Have questions about our methodology? [Contact us →]
Last Updated: March 2026