How to Approach and Answer This Question in a PM Interview

This question evaluates your ability to make educated estimations using logical assumptions and relevant data. Here's how to structure your response:

1. Start with Context

Tip: Explain your understanding of WhatsApp’s global reach and relevance to set the stage.

Say something like:

“WhatsApp is one of the world’s most popular messaging apps, with a significant presence in regions like India, Southeast Asia, Europe, and Latin America. As a messaging platform used for personal, business, and community communication, its daily active users (DAUs) are likely a substantial percentage of its total user base.”

This shows you understand WhatsApp's global positioning and use cases.

2. Break Down the Estimation

Tip: Use logical steps and assumptions to estimate the DAUs.

Step 1: Start with Total Monthly Active Users (MAUs)

• Based on available reports, WhatsApp had approximately 2.5 billion MAUs as of 2024.

• Assume this figure is accurate for your estimation.

Step 2: Determine the DAU/MAU Ratio

• For messaging apps, the DAU/MAU ratio is typically high due to their frequent use.

• Assume WhatsApp has a DAU/MAU ratio of 70–80%, similar to other apps with high engagement.

Step 3: Calculate DAUs Globally

• Taking an average DAU/MAU ratio of 75%:

  • DAUs = MAUs × DAU/MAU ratio = 2.5 billion × 0.75 = 1.875 billion DAUs.