Garment Carbon Passport Estimator

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. Work backwards from the garment. Weigh the finished piece, then get the cut-to-finished ratio from the cutting room, the finished-to-greige ratio from the dye house, and the yarn-to-fabric ratio from the knitter or weaver. Each ratio is a real number somebody in your chain already tracks; assembling them is the first honest thing this exercise makes you do.
2. Set every evidence grade to Default before you enter a single factor. The band you see is the band you actually have. Then upgrade the grades one at a time, only where you hold a document that supports it - a metered electricity bill for the production month, a supplier facility figure with a scope statement, a certificate that names the process rather than the company.
3. Treat wet processing as the stage to interrogate first. It is usually the largest term and it is the one most often filled with a default, so it typically carries more of the band than the other four combined. Confirming a dye house electricity and steam figure moves this estimate further than perfecting any other input.
4. Match the factor to the actual process, not to the fibre. Reactive batch dyeing of cotton and disperse continuous dyeing of polyester differ by a factor of two on water and materially on energy; enzyme stone-wash and pumice stone-wash are different processes with different numbers. A factor picked by fibre name rather than by process route is a default wearing a disguise.
5. Read the band before the number. If the band is wider than the difference you are trying to demonstrate - against a competitor, against last season, against a target - then this estimate cannot support that claim yet, no matter how good the central figure looks.
6. Record which grade you used for each stage alongside the result. A footprint without its evidence grades is not reproducible and not auditable, and in a product passport an unreproducible figure is a liability rather than an asset.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

Substituting

Every grade is Default here, so the band is 60% of the whole number and the estimate spans a factor of four from end to end. Wet processing alone is 2.16 of the 4.77 central figure and 1.30 of the 2.86 band - more than any other stage, and more than fibre and yarn together. Move wet processing alone to a metered primary figure and the band falls from 2.86 to 1.58, a 45% narrowing from a single supplier conversation. Move all five to primary and the band is 0.48, but four of those five conversations bought you less than the first one did. That ordering is the whole value of the tool: it tells you which document to go and ask for.

How to use it

1. Work through the input groups in order — Fibre, Spinning, Fabric Formation, Wet Processing and Garment Make. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Cradle-to-Gate Carbon in the dark results panel — that is the headline figure, expressed in kgCO2e/garment.
4. Check the supporting rows underneath (Lower Bound, Upper Bound, Band Width, Upstream (fibre, yarn, fabric), Conversion (wet processing, make), Widest Single Uncertainty and Fibre-to-Garment Yield Loss) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Deciding which supplier to press for primary data first. The stage with the widest single uncertainty is the one whose document buys the most credibility per conversation, and it is very often the dye house rather than the fibre supplier everyone starts with.
• Answering a brand customer who has asked for a product carbon figure. Sending a range with stated evidence grades is a defensible answer; sending a single number you cannot reproduce is a commitment you may be held to later.
• Testing whether a sustainability claim is supportable before it is made. If the band is wider than the improvement being claimed, the data does not yet support the claim - a check worth running before marketing copy is written rather than after a regulator asks.
• Preparing for a Digital Product Passport dataset. A passport asks what a product carries and how that is known; this produces both, in the shape the question is asked, before any delegated act settles the exact fields.
• Showing why yield matters to carbon. Cutting fibre input from 0.55 to 0.50 kg for the same finished garment removes 0.11 kgCO2e at the fibre stage alone and more downstream, because the material that never becomes a garment was still spun and still dyed.

Reading the result

Typical bands and what each one is telling you.

Assumptions and limits

• This is an estimator for readiness, not a life-cycle assessment and not a compliant product footprint. It stops at the factory gate: no distribution, retail, consumer care or end-of-life. Default factors are indicative industry ranges, not authoritative values, and a figure produced here must not be published as a substantiated environmental claim. Use it to find which stage of your supply chain needs primary data - then go and get that data.
• Every input is bounded to the range normal practice occupies (Fibre Input 0 to 20 kg/garment, Fibre Emission Factor 0 to 30 kgCO2e/kg and Evidence Grade Primary — metered, this batch · Supplier proxy — facility average · Default — regional or industry figure, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Questions people ask