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Growth · Startup

Pirate Metrics (AARRR)

Created by Dave McClure (500 Startups), the AARRR framework breaks the customer lifecycle into five measurable stages: Acquisition, Activation, Retention, Revenue, and Referral. Instead of obsessing over vanity metrics (page views, downloads), AARRR forces you to identify the one metric at each stage that actually matters — and find where your funnel leaks most. Fix the leakiest stage first.

When to use this framework

  • You're getting traffic but not converting users into customers
  • You don't know which part of your funnel is the bottleneck
  • Your team needs a shared language for growth metrics
  • You're planning your first growth experiment sprints
  • Reporting feels scattered — you need a single-page health dashboard

Before you start

You need basic analytics in place (Google Analytics, Mixpanel, Amplitude, or similar) to measure each stage. Even rough estimates are better than guessing.

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Worked Example

Dropbox (2009-2010)

1. Acquisition — How do users find you?

The top of the funnel. How many people visit your site/app? Where do they come from?

List your main channels and which ones drive the most volume and quality. Include organic search, paid ads, social, referrals, content, partnerships, etc.

1. Referral programme (35% — the famous 'give 500MB, get 500MB' two-sided referral) 2. Organic/word-of-mouth (25%) 3. Viral video — 'Dropbox Explained' explainer video drove 75,000 signups in one day (15% at peak) 4. SEO / content (10%) 5. PR / press coverage (10%) 6. Paid acquisition (5% — Drew Houston famously said their CAC exceeded their LTV for paid channels, so they stopped)

Total unique visitors or app downloads per month.

2500000

2. Activation — Do users have a great first experience?

The 'aha moment.' When does a new user first experience the core value of your product?

What specific action signals that a user 'gets it'? E.g., 'created first project,' 'invited a teammate,' 'completed first workflow.' Be precise.

User installs Dropbox on their computer AND saves their first file to the Dropbox folder. The aha moment is seeing that file magically appear on their other device or on the web. It's not signing up — it's experiencing the sync for the first time.

Percentage of visitors who complete the aha moment action.

30

Monthly visitors × Activation rate.

3. Retention — Do users come back?

The most critical stage. If retention is broken, nothing else matters — you're filling a leaky bucket.

How do you define a 'retained' user? Weekly active? Monthly active? What action must they perform? Choose the timeframe that matches your product's natural usage cycle.

A retained user is someone who syncs at least one file in the last 30 days. Dropbox's natural usage cycle is daily for power users, but monthly is the baseline. The key insight: once files are in Dropbox, users are retained almost automatically because their data lives there.

Percentage of activated users who are retained over your chosen period (e.g., Month 1 retention).

75

Activated users × Retention rate.

4. Revenue — Do users pay you?

When and how do users convert from free to paid (or make their first purchase)?

How do you monetise? Subscription, transaction, advertising, marketplace commission? What triggers the conversion from free to paid?

Freemium: 2GB free storage → Pro plan ($9.99/mo for 1TB) when users run out of space. The free tier is generous enough to demonstrate value but limited enough to create natural upgrade triggers. Business plans for teams ($15/user/mo). Conversion trigger: hitting the storage limit.

Percentage of retained users who become paying customers.

4

Retained users × Conversion to paid.

Average monthly revenue per paying customer.

10

Paying customers × ARPU.

5. Referral — Do users tell others?

The viral loop. Each user who refers others reduces your effective CAC.

How do users refer others? Built-in invite system, word of mouth, social sharing, referral programme with incentives? What's the primary referral mechanism?

Two-sided referral programme: both the referrer and the invitee get 500MB of extra free storage. Brilliantly designed because: (1) The reward is the product itself (storage), not a discount. (2) Both sides benefit, so there's no awkwardness. (3) It's easy to share via email, link, or social. (4) Each user can earn up to 16GB through referrals, creating a game-like progression. This programme increased signups by 60% and drove 35% of all new signups at its peak.

Percentage of users who refer at least one other user. Also known as K-factor input.

35

6. Funnel Diagnosis

Look at the full funnel. Where is the biggest drop-off? That's where you should focus first.

End-to-end conversion rate from top of funnel to paying customer.

Based on the numbers above, which stage has the worst conversion? That's your priority. Don't try to fix everything at once — fix the biggest leak first.

Activation (70% drop-off from signup to first sync). The biggest challenge was getting users to actually install the desktop app after signing up on the web. Many users signed up but never installed. Solution: the post-signup flow was redesigned to make installation the immediate next step, with a progress checklist ('Get Started: 1. Install Dropbox, 2. Put a file in your Dropbox folder, 3. Install on another computer').

What's one experiment you can run this week to improve the leakiest stage? Be specific about the hypothesis, the change, and how you'll measure it.

Hypothesis: Adding a 'Getting Started' checklist to the web dashboard will increase the desktop install rate from 30% to 45%. Change: Add a persistent onboarding widget showing 4 steps (install, add file, share folder, install on second device) with a progress bar and a reward (bonus 250MB) for completing all steps. Measure: Track % of new signups who complete each step within 7 days.
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