Pirate Metrics is the AARRR framework, coined by Dave McClure, that breaks SaaS growth into five measurable stages: Acquisition, Activation, Retention, Revenue, and Referral. The name comes from the acronym sounding like a pirate. It's meant to be used, not admired.
Each stage tracks a different part of the user journey. Together they show you exactly where growth is leaking.
The five stages
Acquisition is how users find you: search, ads, content, word of mouth.
Activation is when a user first gets real value from the product. Not signing up. Actually doing something useful.
Retention is whether they come back. It's the most honest signal of product quality.
Revenue is conversion from free to paid, or expansion from existing customers.
Referral is users bringing in other users, which lowers acquisition costs over time.
How to use it
Pick the stage with the worst numbers and fix it before moving to the next. You can't optimize everything at once. Most teams find their activation or retention is worse than they assumed. Track your feedback boards to see if users are getting enough value to return.