The Spend-based method is a widely used and scalable technique to estimate the environmental impact of goods and services. It estimates it by collecting data on the economic value of goods and services purchased and multiplying it by relevant secondary (e.g., industry average) emission factors (e.g., average emissions per monetary value of goods).

It is important to note the due to the use of industry averages, the emissions estimates obtained will be not completely accurate. It is very common in the clothing industry to see disparity between different companies on their pricing for items, so under the spend based method a jacket would account the same as a t-shirt with the same price. In many cases activity data is more accurate and scientifically sound, although slower and more resource intensive to scale.

Source: GHG Corporate Standard