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Supply Chain Carbon Emission Footprint Calculator

The Supply Chain Carbon Emission Footprint Calculator estimates emissions from four common supply-chain activity pools: purchased goods or services, freight, supplier electricity, and waste. Rather than embedding generic coefficients, it asks you to enter the emission factor for each activity so the estimate can reflect your chosen database, supplier data, transport mode, grid, and accounting boundary.

The calculator is useful for procurement and sustainability teams that want a quick, auditable view of where modeled supply-chain emissions are concentrated. It reports total tCO2e plus each component separately, which can help prioritize supplier engagement or data improvement. It is not a complete Scope 3 inventory by itself; categories such as capital goods, business travel, use of sold products, or end-of-life treatment may need separate treatment depending on your boundary.

Supply chain activity data and emission factors

$
kg CO2e/$
tonne-km
kg CO2e/tkm
kWh
kg CO2e/kWh
kg
kg CO2e/kg
Result
—
estimated supply chain footprint
Purchased goods/services—
Freight emissions—
Supplier electricity—
Waste emissions—

1. Set the inventory boundary
Choose the reporting period, suppliers, purchasing scope, freight legs, electricity data, and waste flows included in the estimate.

2. Enter purchasing activity
Add spend and a compatible kg CO2e per dollar factor. If you have supplier-specific physical data, a more detailed method may be preferable.

3. Enter freight activity
Use tonne-kilometers and a factor that matches the transport mode or weighted modal mix.

4. Add supplier electricity and waste
Pair each activity value with an emission factor using the exact unit shown in the field.

5. Use the breakdown to prioritize data
Compare the four component results and investigate the largest or least certain sources first.

Component emissions (tCO2e) = Activity × Matching emission factor (kg CO2e per activity unit) ÷ 1,000Total supply chain footprint = Purchased goods/services + Freight + Supplier electricity + Waste emissions

Emission factors must match the unit of each activity field. Mixing currencies, tonne-km definitions, or electricity factors without conversion will distort the result.

What the result means

The main result is the combined tCO2e estimate for the four supply-chain activity pools included in this calculator.

This simplified model does not replace a complete value-chain greenhouse-gas inventory or supplier-specific life-cycle assessment.

Given

  • Purchasing: $1,500,000 at 0.32 kg CO2e/$
  • Freight: 900,000 tonne-km at 0.09 kg CO2e/tkm
  • Supplier electricity: 650,000 kWh at 0.38 kg CO2e/kWh
  • Waste: 48,000 kg at 0.50 kg CO2e/kg

Calculation
Purchased goods/services = 480 tCO2e; freight = 81 tCO2e; supplier electricity = 247 tCO2e; waste = 24 tCO2e. Total = 480 + 81 + 247 + 24.

Result
832 tCO2e estimated supply chain footprint.

In this simplified scenario, purchased goods/services are the largest modeled component, followed by supplier electricity.

Why does the purchasing input use spend rather than physical quantities?

Spend-based factors can provide a broad estimate when supplier-specific physical data are unavailable. They are often less specific than activity- or product-based data, so improve the method as better information becomes available.

Can freight factors differ by mode?

Yes. Road, rail, air, and sea freight can use different factors. For a mixed network, calculate modes separately or use a weighted factor that matches the tonne-km input.

How do I avoid double counting supplier electricity?

Define boundaries before entering data. If electricity emissions are already embedded in a supplier-specific product footprint used elsewhere, adding them again may double count the same source.

Why are all factor outputs converted to tCO2e?

The inputs use factors in kg CO2e per activity unit. Dividing by 1,000 puts every component on the same tCO2e basis before they are summed.

Does this cover every Scope 3 category?

No. It is a simplified supply-chain model with four activity pools. A complete value-chain inventory may require additional upstream and downstream categories.