#ghg protocol

The same litre of diesel can land in three different places on your carbon inventory. Burned in a company van, it's Scope 1 mobile combustion. Burned in a fixed standby generator, it's Scope 1 stationary. Burned in a courier's own vehicle, it's Scope 3. The chemistry is identical — DEFRA's 2025 factor is 2.57082 kg CO₂e per litre either way — but the asset class decides the line, and misclassifying it is one of the most common Scope 1 audit findings.

This calculator runs the DEFRA 2025 factor set across all 15 mobile fuels — diesel, petrol, LPG, marine grades, aviation, CNG, LNG — and bundles the CO₂, methane, and nitrous oxide into a single CO₂e value automatically. Pick your fuel and unit basis (litres, tonnes, or kWh), enter the quantity, and it returns an audit-ready figure with the full calculation chain exportable for verification.

One genuinely useful detail it gets right: it inherits DEFRA's native AR5 GWP basis rather than silently "converting" to AR6, which keeps a single factor honest to its source even in an AR6 inventory.

Scope 3 Category 1 (Purchased Goods & Services) is usually the biggest line on a corporate emissions inventory — CDP's data puts supply-chain Scope 3 at roughly 26× operational emissions across manufacturing, retail, and materials. It's also the line auditors scrutinise first, because spend-based estimates carry the lowest data quality score under PCAF (4 or 5 out of 5).

This calculator runs the spend-based method properly: pick EPA USEEIO, EXIOBASE 3.8.2, or Defra 2025 factors per supplier line, enter spend in native currency, and it auto-deflates for inflation and converts FX to the factor's base year — the two normalisation steps that silently swing audited inventories 15–25% when skipped. Every line gets a PCAF score, and the tool flags which suppliers to engage first for primary data.

Scope 2 reporting isn't just a tally of kilowatt-hours—it is a mandatory dual-reporting framework.

Under the GHG Protocol Scope 2 Guidance, companies must calculate emissions using two distinct methodologies: Location-based (the average intensity of the grid) and Market-based (the specific energy you chose to buy).

We’ve codified this dual-logic into an audit-ready interface. No spreadsheets, no hidden math. Just pure, deterministic normalization of grid factors and residual mixes.

One of the most common errors in carbon accounting is Scope misclassification based on fuel type.

The Logic: You burn 1,000L of diesel in a backup generator? That is Scope 1 Stationary Combustion.

The Logic: You burn the exact same 1,000L of diesel in a delivery van? That is Scope 1 Mobile Combustion.

In the GHG Protocol Corporate Standard (§4.1), the "Scope Line" is drawn by the stationary or mobile nature of the asset, not the chemical composition of the fuel. Accuracy in reporting depends on mapping data flows to asset registries, not just utility invoices.