SROI measures the social, environmental and economic results (outcomes), and uses monetary terms to show these outcomes. This allows to calculate the cost/benefit ratio. For instance: a 3:1 ratio shows that a 1€ invest generates 3€ of social value.
In the same way that a business plan contains much more than financial projections, SROI is much more than a simple figure. It is a story about the change caused by impact.
Social ROI measures extra-financial value (like social or environmental value) and calculates the added value for society according to the investments made.
The goal is to quantify social value in the same terms used in marketing: money. This way a new piece of information is obtained to take decisions about resources assignment.