Report Tooltips — Use report tooltips (page tooltips) (intro)

Historical Context & Motivation

The concept of a tooltip — a small informational overlay that appears when a user hovers over an interface element — has been a cornerstone of graphical user interfaces since the early days of desktop computing. In the context of data visualization, tooltips serve as a mechanism for progressive disclosure, a design pattern in which details are revealed on demand rather than cluttering the primary view. Microsoft Power BI adopted this principle early on, initially offering only simple text-based tooltips that displayed a data point's category and value. As the platform matured, report authors increasingly demanded richer hover experiences — the ability to embed entire charts, KPIs, and images inside a tooltip. Microsoft responded by introducing report tooltips (also called page tooltips), a feature that lets you designate an entire report page as a tooltip surface, unlocking multi-visual hover panels that respond dynamically to the data context of the hovered element.

The central question that report tooltips address is straightforward yet significant: how can a report surface deep contextual detail without sacrificing visual simplicity? Default tooltips answer this question only superficially — they show a few numbers. Report tooltips answer it comprehensively by treating the hover interaction as a window into an entire supplementary page of analysis, dynamically filtered to the data point under the cursor.

Core Principles & Definitions

Before building a report tooltip, it is essential to understand the architectural concepts that distinguish page tooltips from their simpler counterparts. At the implementation level, a report tooltip is a hidden report page whose page size is intentionally small (typically 320 × 240 pixels by default) and whose page information property is configured so that Power BI treats it as a tooltip rather than a standard navigation page. The following foundational ideas govern how this mechanism works.

Visual Explanation — How Report Tooltips Work

The visual above captures the key architectural relationship between the main report page and the tooltip page. Notice that the tooltip page is a full Power BI page in its own right — it can contain any combination of visuals, text boxes, shapes, and images. The critical mechanism is the filter context propagation: when the user's cursor enters a data point, Power BI constructs a filter tuple (e.g., Category = 'C', Quarter = 'Q3 2024') and applies it to the tooltip page exactly as if the user had applied those filters manually. This means every DAX measure, every slicer interaction, and every cross-filtering relationship on the tooltip page responds to the hovered data point's context. From a software engineering perspective, this is analogous to dependency injection — the tooltip page's behavior is parameterized by the filter context it receives at render time.

How It Works — Configuration Deep Dive

Building a report tooltip involves a precise sequence of configuration steps across two surfaces: the tooltip page itself and the consuming visual that triggers it. Understanding these steps at a granular level is critical because a misconfigured property — an oversized page dimension, a missing toggle — will silently prevent the tooltip from appearing. Let us walk through the mechanism in detail.

Step A — Create and Size the Tooltip Page

Create a new page in your report (right-click the page tab bar and select New page). Navigate to Format > Canvas settings (in the Visualizations pane) and set the Type to Tooltip. Power BI automatically adjusts the page dimensions to 320 × 240 pixels, though you can override these values. The constrained canvas forces you to prioritize the most valuable supplementary information — think of it as designing a responsive micro-frontend with a fixed viewport.

Step B — Enable the Tooltip Toggle

In the same Format pane, expand Page information and toggle Allow use as tooltip to On. This is the single boolean flag that registers the page in Power BI's internal tooltip registry. Without it, the page exists as a normal (albeit small) report page and will never appear on hover. It is helpful to give the page a descriptive name — for instance, Tooltip_ProductDetail — so that you can easily identify it when assigning it to visuals later.

Step C — Design the Tooltip Content

Add visuals, text boxes, shapes, and images to the tooltip page just as you would on a regular page. Common patterns include a sparkline for trend context, a card visual for a headline KPI, and a conditional image (e.g., a product photo loaded via a URL column). Because the canvas is small, avoid visuals with heavy axis labels or legends — they consume disproportionate space. Consider disabling visual headers on the tooltip page's visuals to maximize the data-to-ink ratio.

Step D — Assign the Tooltip to Visuals

Return to your main report page, select the visual you want to attach the tooltip to, and open its Format > Tooltip settings. Set the Type dropdown to Report page and then select the specific tooltip page from the Page dropdown. If you leave the page set to Auto, Power BI will automatically match tooltip pages based on which fields are present in both the visual and the tooltip page's filter context — a form of implicit binding that mirrors convention-over-configuration in frameworks like Spring or Ruby on Rails.

Design Patterns & Classification

Report tooltips are versatile enough to serve multiple analytical purposes. In practice, report authors converge on a few recurring design patterns, each optimized for a different type of supplementary insight. Understanding these patterns will help you select the right tooltip architecture for your use case, much like understanding software design patterns (Observer, Strategy, Factory) helps you choose the right abstraction for a given problem.

Worked Example — Building a Trend Tooltip

Let us walk through a concrete example. Suppose you have a sales report with a clustered bar chart showing total revenue by product category. You want a hover interaction that reveals a 12-month revenue trend for whichever category the user hovers over, along with year-over-year growth.

Strengths & Limitations

Report tooltips are a powerful design tool, but like any abstraction, they introduce trade-offs. Understanding these trade-offs is critical for making informed design decisions — you would not use a microservices architecture for a simple CRUD app, and similarly you should not use page tooltips when a simple default tooltip suffices.

Connection to Advanced Tooltip Techniques

The introductory report tooltip concepts covered in this lesson form the foundation for several advanced techniques that Power BI authors use in production environments. As you progress, you will encounter scenarios that demand more sophisticated tooltip architectures, including conditional tooltip switching, tooltip pages driven by complex DAX, and integration with Power BI Embedded for programmatic tooltip control.

As with any layered abstraction — think of it as moving from basic HTTP requests to building a REST API framework — the introductory concepts you have learned here are prerequisites for every advanced technique. Mastering the page creation workflow, filter context propagation, and visual-level assignment gives you the mental model needed to reason about more complex tooltip architectures. In subsequent lessons, we will explore conditional tooltip switching using DAX and multi-tooltip report designs.

Practice Problems

Lesson Summary