Methodology

How Rewoven calculates sustainability

We believe a sustainability rating is only useful if you can see how it was made. Here's exactly what each number means, how it's derived, and the data behind it - including where something is a measured fact, a sourced assessment, or an estimate.

The short version: we never invent data. Facts we read from a product page (like fabric composition and price) are shown as-is. Brand ratings are our sourced, editorial assessments. Environmental footprints are estimates calculated from published per-fibre research averages - clearly marked with a “~”. When a page doesn't list its fabric, we say so instead of guessing.

1. Brand sustainability ratings

Each brand's overall score (0-100) and A-F grade is the equal-weighted average of four dimensions: environmental impact, labor practices, transparency, and animal welfare. Scores are assigned from publicly available information - brand sustainability reports, third-party certifications, and reputable reporting.

These ratings are Rewoven's editorial assessments and expressions of opinion, not statements of fact. They reflect information available at the time of review and may not capture a brand's most recent changes. A brand that believes its rating is inaccurate can request a review at arhan@rewovenapp.com.

2. Material footprint estimates

When a product page lists its fabric composition (e.g. 60% cotton, 40% polyester), we estimate a footprint by combining:

the composition read directly from the page,
published cradle-to-gate averages for each fibre (kg CO₂e and litres of water per kg of fibre), and
an average garment weight for the product category.

These are estimates, not measurements. Real impact varies enormously by region, farm, mill, energy source, and dyeing/finishing. Treat the figures as relative, order-of-magnitude guidance - useful for comparing materials, not as a precise measurement of a specific garment. That's why they're shown with a “~”.

If a page doesn't publish its composition, we don't estimate a footprint at all - the extension shows “composition not listed” rather than a made-up number. Cost-per-wear is only shown when a real price is available.

3. Data sources

The per-fibre coefficients are rounded industry averages compiled from, and kept consistent with, these public sources. Where sources disagree, we use a representative mid-range value.

Ellen MacArthur Foundation - A New Textiles Economy: Redesigning fashion's future (2017)
Water Footprint Network - Mekonnen & Hoekstra, water footprint of crops (cotton ≈ 10,000 L/kg global average). waterfootprint.org
Textile Exchange - Preferred Fiber & Materials Market Report. textileexchange.org
Higg Materials Sustainability Index (Higg MSI) - cradle-to-gate material impacts. cascale.org
Quantis - Measuring Fashion: environmental impact of the global apparel and footwear industries (2018). quantis.com

4. What we deliberately don't do

We don't invent statistics. No fabric data on the page → no footprint shown.
We don't show a footprint for unidentified fibres.
We don't show cost-per-wear without a real price.
We only describe figures as “estimates from research” when actual estimates are shown.
We don't run on non-fashion products - the lens only activates on clothing and footwear.

Spotted something inaccurate? Tell us at arhan@rewovenapp.com and we'll review it.