What is ROI?

ROI is one of the most universal metrics in business — applicable to marketing spend, capital purchases, hiring decisions, software subscriptions, and any other allocation of resources. At its most basic: if you spend $1,000 on advertising and generate $3,000 in revenue directly attributed to those ads, your ROI is 200% (($3,000 − $1,000) ÷ $1,000).

In practice, calculating marketing ROI accurately is harder than it looks. Attribution — determining which channel or touchpoint actually caused a conversion — is notoriously difficult in multi-channel environments. Customers often encounter a brand through organic search, then convert after a retargeting ad or an email — which channel gets the credit? Different attribution models (first-touch, last-touch, linear, data-driven) produce different answers.

ROI is also time-horizon-dependent. Some investments have poor short-term ROI but excellent long-term ROI — content marketing and brand building are good examples. Others have excellent short-term ROI but can't be scaled without diminishing returns — certain paid acquisition channels. Comparing ROI across investments requires aligning the time horizon and accounting for risk, which is why more sophisticated business decisions use metrics like NPV (Net Present Value) and IRR (Internal Rate of Return) instead of simple ROI.