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

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
• Emissions share for a buyer's orders
• Footwear emissions per pair

Sources: GHG Protocol Scope 3 Standard, ISO 14064-1, 14064-3 and 14067 (iso.org), GHG Protocol standards

Last reviewed 2026-10-22.