Heart framework
HEART is a metrics framework developed by Google to measure user experience at scale. The acronym represents five categories: Happiness, Engagement, Adoption, Retention, and Task Success. Unlike business metrics that focus on revenue and growth, HEART centers on user experience-how people feel about and interact with your product.
The five dimensions
Happiness measures users' subjective satisfaction with the product. This typically comes from surveys, ratings, and qualitative feedback. Metrics might include Net Promoter Score, satisfaction surveys, or in-app ratings.
Engagement captures how deeply users interact with the product. Depending on the product, this might be session length, features used, actions taken, or frequency of specific behaviors. The key is measuring intensity of use, not just occurrence.
Adoption tracks new users and new feature uptake. How many new users start using the product? How many existing users adopt new features? This reveals whether the product is expanding its reach and whether new capabilities resonate.
Retention measures whether users come back over time. Daily, weekly, or monthly active user rates, cohort retention curves, and churn rates all fall here. Retention often matters more than acquisition for sustainable growth.
Task Success evaluates whether users can accomplish what they came to do. This includes effectiveness (did they succeed?), efficiency (how long did it take?), and error rates (what went wrong?). Task-specific metrics depend heavily on the product's purpose.
Applying heart with gqm
Google recommends combining HEART with the Goal-Question-Metric approach for practical implementation:
Not every product needs all five categories. A consumer app might emphasize Engagement and Retention, while a productivity tool might prioritize Task Success. The framework provides structure while allowing customization.
Example: email application
| Category | Goal | Question | Metric |
|---|---|---|---|
| Happiness | Users feel the app makes email manageable | Do users rate the app positively? | App store rating, NPS |
| Engagement | Users actively manage email | How much do users interact? | Emails processed per session |
| Adoption | New users successfully onboard | Do signups become active users? | 7-day activation rate |
| Retention | Users continue using the app | Do users return regularly? | Weekly active user retention |
| Task Success | Users can find and process emails efficiently | Can users complete key tasks? | Search success rate, time to respond |
Why heart works
User-centered by design. Business metrics like revenue can improve while user experience degrades (through aggressive monetization, for example). HEART keeps focus on user outcomes.
Comprehensive coverage. The five dimensions cover different aspects of user experience that don't always move together. A product can have high engagement but low happiness, or high adoption but poor retention.
Actionable categories. Each dimension suggests different interventions. Low task success points to usability improvements. Low retention suggests value delivery problems. The framework guides investigation.
Balances subjective and objective. Happiness captures how users feel; Task Success and Engagement capture what they do. Both perspectives matter for understanding experience.
Heart limitations
Survey fatigue. Happiness typically requires asking users, which competes for attention and can introduce bias.
Metric selection complexity. Within each category, choosing the right specific metric requires judgment. Engagement for a social app differs fundamentally from engagement for a banking app.
Category overlap. The dimensions aren't perfectly independent. High task success often drives happiness. Strong engagement often correlates with retention. Interactions can make interpretation complex.
Lagging indicators. Some HEART metrics, particularly retention, reflect past decisions. By the time retention drops, the underlying problem may have existed for months.
Not for early-stage products. HEART assumes enough users to generate meaningful data. Very early products may need qualitative approaches before HEART becomes useful.
Implementing heart
Start with goals. Don't measure everything possible. Identify which HEART dimensions matter most for your product and current stage.
Choose representative metrics. Within each dimension, select metrics that truly indicate the category. Session length might indicate engagement or might indicate users struggling to complete tasks.
Establish baselines. Know where you are before trying to improve. Baseline measurements reveal which dimensions need attention.
Watch for tensions. Improving one dimension can hurt another. Reducing friction (Task Success) might reduce engagement time. Understand trade-offs.
Combine with qualitative research. HEART metrics show what's happening. User research reveals why. Both are needed.
Tools like Klero complement HEART by providing qualitative context for quantitative metrics. When Happiness scores drop, feedback data helps explain why. When Adoption stalls, user requests reveal what's missing. The combination creates a more complete picture of user experience.
