Marketing KPIs: a KPI definition and examples you can use
What a KPI is, how it differs from a metric, and the marketing KPI examples that actually tie to revenue, with how to track them in GA4.
Most marketing reports are full of numbers and short on answers. Impressions are up, followers are up, and nobody can say whether the business is better off. That is usually not a data problem. It is a KPI problem.
Here is a useful KPI definition, the difference between a KPI and a metric, and the marketing KPIs worth tracking.
KPI definition
A KPI, or key performance indicator, is a number you have chosen in advance to tell you whether you are reaching a specific goal. The word that matters is "key." A business can track hundreds of metrics. It should have only a handful of KPIs, and each one should connect to an outcome the business cares about, like revenue, leads or retained customers.
A simple test: if a number went up 20% this month, would anyone change what they do? If not, it is a metric, not a KPI.
Metrics vs. KPIs
- Metric: anything you can measure. Page views, likes, email opens, time on page.
- KPI: the few metrics tied to a goal, with a target and an owner. "Cost per qualified lead under $80 by December" is a KPI. "Page views" on its own is not.
Metrics are still useful. They help explain why a KPI moved. They just should not be the headline.
Marketing KPI examples that tie to revenue
Customer acquisition cost (CAC). Total marketing and sales spend divided by the number of new customers in the same period. If you spend $10,000 and win 50 customers, CAC is $200.
Cost per lead (CPL). Spend divided by leads. Useful, but only when "lead" is defined tightly. A form fill from a competitor is not a lead.
Conversion rate. The share of visitors or clicks that take the action you want. Track it per channel, because a single site-wide average hides your best and worst sources.
Return on ad spend (ROAS). Revenue from ads divided by ad spend. $5,000 in revenue on $1,000 in spend is a ROAS of 5.
Customer lifetime value (LTV). The revenue a typical customer brings in over the whole relationship. Comparing LTV with CAC tells you how much you can afford to spend to win a customer.
Lead-to-customer rate. The share of leads that become paying customers. If this is low, more leads will not fix the problem.
How to track marketing KPIs in GA4
Google Analytics 4 calls the actions that matter most to your business key events, and you choose which events count. Google's list of recommended events includes generate_lead, for a form or request for information, and purchase, for a completed sale. Mark the ones that match your goals as key events, and GA4 will report them by channel.
GA4's default channel groups then sort that traffic into channels like Organic Search and Paid Search. One detail worth knowing: Google's definition of Organic Search includes visits from links in Google's AI Overviews and AI Mode, so visits from those two Google features show up there. Visits from assistants like ChatGPT, Gemini and Copilot land in a separate AI Assistant channel.
How many KPIs should you have?
Fewer than you think. Three to five for the whole marketing function is plenty, with each one owned by a person and reviewed on a set schedule. Everything else is supporting detail. The point of a KPI is to make decisions easier. If yours are not doing that, you have too many, or the wrong ones.
Sources
Checked October 3, 2026. Platforms change their guidance. The linked pages are the final word.
