# A buyer wants a carbon figure on every invoice line. How do I do that?

Canonical: https://senseible.earth/answers/carbon-per-invoice-line-for-quotes

Work out kg CO2e per unit for each product once, from your yearly Scope 1 and 2 and the inputs each product uses, then multiply by the quantity on each line. Update the per-unit figure when your inventory changes, and state the period and method on the invoice.

## Steps

1. Build a yearly per-unit figure per product, with a stated allocation rule.
2. Store it as a product attribute in your billing system.
3. Print quantity x per-unit figure on each line, with the basis year.

## Keep it defensible

- Do not recalculate per invoice from that month's bills; seasonal swings confuse buyers.
- Say whether the figure is cradle to gate.
- Keep the workings ready for review.

## What Senseible does here

Senseible reads bills, fuel invoices and production records into dated, fingerprinted records, so the figure you send a buyer can be traced to its documents.

- [Buyer asks for a PCF](https://senseible.earth/answers/buyer-asked-for-product-carbon-footprint-what-to-send)
- [One dataset for several buyers](https://senseible.earth/answers/one-carbon-dataset-for-several-buyers)
- [Split by product line](https://senseible.earth/answers/buyer-asks-scope-1-2-split-by-product-line)

Sources: [GHG Protocol standards, including the Product Standard](https://ghgprotocol.org/standards), [GHG Protocol Corporate Standard](https://ghgprotocol.org/corporate-standard)

Last reviewed 2026-10-22.