Social ROI is return on investment applied specifically to social media: the business value your social efforts produce — revenue, leads, sign-ups, retained customers — measured against everything they cost, including media, tools and team time. It is how you prove that social is a channel that pays, not just a presence you maintain.
It matters because social's value is often real but indirect, and without a deliberate measurement approach it gets dismissed as unmeasurable. Attribution is genuinely hard — the path from a Reel view to a sale can be long and cross several sessions — so social ROI usually blends hard conversions with assisted value and, where relevant, earned media value.
Build it by defining the goals that map to money, tagging links and using promo codes, watching assisted conversions rather than last-click alone, and comparing return across content types and campaigns. Report a small set of outcomes leadership recognises, not a wall of vanity metrics.