One of the latest accessibility checks I’ve added to PBIX A11y looks at something many Power BI developers rarely think about: the size of interactive elements.
Things like buttons, slicers, navigation items and clickable icons.
At first glance, this might seem like a small detail. But when you stop and think about how people actually interact with reports, it becomes surprisingly important.
I notice it all the time, specially when using my mobile phone. I’ll try to tap a tiny icon or menu item and end up hitting the wrong thing entirely. Having nerve damage in my hands certainly doesn’t help, but honestly, even people without dexterity difficulties find small tap targets frustrating.
And if a control is difficult to activate, it doesn’t matter how beautiful the report looks. It’s creating friction for the user.
That’s exactly the problem that WCAG 2.2 Success Criterion 2.5.8 – Target Size (Minimum) was introduced to address.
What is WCAG 2.5.8?
WCAG (Web Content Accessibility Guidelines) is the internationally recognised standard for digital accessibility.
In WCAG 2.2, a new requirement was introduced to address one of the most common usability issues in digital products: controls that are simply too small to interact with comfortably.
Success Criterion 2.5.8 states that interactive targets should be at least 24 × 24 CSS pixels, unless specific exceptions apply.
The goal is straightforward. People shouldn’t need pinpoint precision to click or tap something.
The criterion particularly benefits users with:
- Motor impairments
- Tremors
- Arthritis
- Limited dexterity
- Temporary injuries
- Touchscreen devices
But in reality, it benefits everyone.
Most of us have experienced tapping the wrong thing because the target was too small or too close to another control. WCAG 2.5.8 helps reduce those errors and makes interactions more reliable.
Why This Matters in Power BI
Power BI reports contain a surprising number of interactive elements:
- Buttons
- Slicers
- Navigation menus
- Bookmark controls
- Drill-through actions
- Icons used for navigation
Because report designers are often trying to maximise screen space, these controls can gradually become smaller and smaller.
The result is a report that technically works but feels frustrating to use.
While Power BI isn’t a website, the same accessibility principles apply. If users struggle to activate a control, they’re encountering a barrier.
For this reason I included another check on the PBIX Accessibility Audit built-in PBIX A11y, to identify controls that may be too small before a report is published.
How the New Check Works
The new PBIX A11y rule evaluates interactive elements and categorises them into three levels:
Below 24 × 24 pixels → High accessibility risk
24 × 24 to 39 × 39 pixels → Meets the WCAG minimum but could be improved
40 × 40 pixels or larger → Recommended good practice
The first threshold comes directly from WCAG 2.2. However, I didn’t want PBIX A11y to stop at compliance.
One of the things I’ve learnt through accessibility work is that passing a standard doesn’t automatically create a great user experience.
That’s why the tool also includes a recommended target size.
Why PBIX A11y Recommends 40 × 40 Pixels
Although WCAG sets a minimum target size of 24 × 24 pixels, most major design systems recommend significantly larger targets.
Microsoft’s Fluent Design guidance uses a 40 × 40 pixel touch target as a balance between information density and ease of interaction.
Apple’s Human Interface Guidelines recommend a minimum touch target of 44 × 44 points.
Google’s Material Design guidance recommends 48 × 48 dp, which equates to roughly 9 mm of physical touch area regardless of screen size.
The reasoning is simple: larger targets are easier to hit accurately. Users make fewer mistakes, interact more quickly and experience less frustration.
I particularly like thinking about it this way:
WCAG defines the minimum acceptable size. Design systems define the recommended size.
That’s why PBIX A11y treats 24 × 24 pixels as the accessibility threshold but recommends aiming for 40 × 40 pixels or larger whenever practical.
One Important Caveat
The recommended 40 × 40 pixel size assumes a standard Power BI canvas of 1280 × 720.
If you’re designing on a larger canvas, such as 1920 × 1080, those controls should scale proportionally.
A 40 × 40 pixel button on a 1920 x 1080p canvas occupies a much smaller relative area than the same button on a 1280 x 720p canvas.
This is something I discuss in more detail in The Missing Rule for Power BI Layouts, where I explore why fixed dimensions alone don’t always tell the whole story.
Accessibility isn’t just about meeting a number. Context matters.
Wrap-Up
Larger targets obviously help people with motor impairments, but they also make a noticeable difference for anyone using a laptop trackpad, a touchscreen device, a tablet, or even a phone while rushing between meetings, where precision simply isn’t realistic.
When controls are easier to hit, there are fewer misclicks, less back-and-forth trying to correct mistakes, and a much smoother overall experience that reduces frustration without users even thinking about it.
Thank you for joining me on this journey. Until next time, let’s keep crafting accessible and ethical insights that make a difference!
