How to Measure Marketing Performance: Key Metrics (CPI, CPA, LTV, ROAS)

Why Marketing Metrics Matter

Without clear metrics, you can’t scale efficiently. Performance marketing relies on data to make decisions.

1. CPI (Cost Per Install)

Definition: Cost to acquire one app install.

Formula:

CPI = Ad Spend / Number of Installs

Use CPI to evaluate:

• Channel efficiency
• Creative performance

2. CPA (Cost Per Acquisition)

Definition: Cost to acquire a paying customer or lead.

Formula:

CPA = Ad Spend / Conversions

CPA is more valuable than CPI because it reflects real business outcomes.

3. LTV (Lifetime Value)

Definition: Total revenue generated by a user over time.

Key factors:

• Retention
• Monetization
• Engagement

LTV helps determine how much you can afford to spend on acquisition.

4. ROAS (Return on Ad Spend)

Definition: Revenue generated per dollar spent.

Formula:

ROAS = Revenue / Ad Spend

Track:

• Day 1 ROAS
• Day 7 ROAS
• Day 30 ROAS

How These Metrics Work Together

• CPI tells you acquisition cost
• CPA shows conversion efficiency
• LTV defines user value
• ROAS measures profitability

Golden rule:

LTV must be higher than CPA for sustainable growth.

Common Pitfalls

• Focusing only on CPI instead of CPA
• Ignoring long-term LTV
• Not segmenting users by cohort
• Making decisions on incomplete data

Strong performance marketing depends on understanding the relationship between cost, value, and revenue. The right metrics help you scale confidently.