# My buyer wants carbon per kg, but we track it per piece. How do we convert?

Canonical: https://senseible.earth/answers/buyer-wants-carbon-per-kg-not-per-piece

Divide the per-piece figure by the net weight of one piece, from your drawing or a scale. If you make many sizes, allocate plant emissions by weight of good output in the first place, which gives a per-kg figure directly and a per-piece figure for each size by multiplying back.

## Which weight

- Net weight of the finished piece, not the gross weight including runners or offcuts.
- Packaging excluded unless the buyer asks for it.

## When per kg misleads

Machined or plated parts use energy per piece more than per kg. Say so, and offer both figures with the method.

## Keep it consistent

Use the same allocation every year and the same weights the buyer sees on your invoices or packing lists.

## What Senseible does here

Senseible reads your fuel, electricity and purchase documents into dated, fingerprinted records, so the figure you send a buyer can be traced to its source.

- [Rejects and yield loss](https://senseible.earth/answers/rejected-batches-and-yield-loss-in-product-footprint)
- [Emissions share for a buyer's orders](https://senseible.earth/answers/buyer-asks-emissions-share-for-its-orders)
- [Footwear emissions per pair](https://senseible.earth/answers/footwear-factory-emissions-allocation-per-pair)

Sources: [GHG Protocol Scope 3 Standard](https://ghgprotocol.org/corporate-value-chain-scope-3-standard), [ISO 14064-1, 14064-3 and 14067 (iso.org)](https://www.iso.org), [GHG Protocol standards](https://ghgprotocol.org/standards)

Last reviewed 2026-10-22.