For most contractors, purchased goods and services are the largest part of the footprint, and for many suppliers the only data available is what was spent. Spend-based factors turn pounds into emissions. They are an estimate, and they can still be done carefully.
Name the industry
A spend factor only means something for a particular industry. MetricOra prices a spend record through the supplier's industry code on the record: a UK SIC code, a US NAICS code or a French NAF code. Without a code, the record is not priced from an industry library and the calculation asks you to add one. It does not fall back to a generic average.
For pounds sterling, the factors come from the Defra and University of Leeds UK spend multipliers, published under the Open Government Licence for 111 UK SIC groups. For dollars, MetricOra uses EPA USEEIO 1.3. For euros, it uses ADEME's ratios by NAF division.
Use the factor's prices
Spend factors are published at a particular year's prices. Money spent in 2025 buys less than it did in 2023, so it is deflated to the factor's price year before the factor is applied. For sterling, MetricOra uses the ONS consumer price index. Spend in another currency is first converted at the ECB rate for the record's date.
A worked example
Our demo contractor spent £369,000 on ready-mix concrete in the first quarter of 2025, recorded with UK SIC 23.63. The run stores:
Adjusted 2025 GBP spend to 2023 prices (× 0.9429, CPI).
347,937.14 GBP × 2.08125 kg CO2e/GBP = 724,144.17 kg CO2e
The selection reason records that SIC 23.63 matched group 23.5-6, "Cement, lime, plaster and articles of concrete, cement and plaster", in the Defra UK spend multipliers 2023, the spend library for GBP.
Where to go next
Spend-based figures are a starting point. When a supplier can give you their own emissions, or a product has an EPD, MetricOra lets you replace the estimate with that data. Until then, a sourced factor, the right industry and the right price year keep the estimate defensible.