Minimum accessible font size checker for body, captions and buttons

This checker compares a font size in CSS pixels with a practical minimum for body text, captions, or button labels. It reports the applicable threshold, whether the size meets it, and the exact difference. The result is guidance for an early accessibility review, not a claim that font size alone makes a design accessible.

Choose the content role before judging the number

A font size does not communicate enough by itself because text serves different purposes. Body copy carries sustained reading and therefore uses a common minimum of 16 CSS pixels in this checker. Captions are shorter and secondary, so the comparison threshold is 12 pixels. Button labels must remain legible while also fitting a control, and this checker uses 14 pixels for that role. Select the role that describes how the words function, not how the text happens to look. A line below an image is a caption even if it uses the same typeface as an article. Text inside an actionable control is a button label even when the control has been styled to resemble a link. Keeping the role explicit makes repeated audits consistent across pages and prevents teams from quietly applying the smallest threshold to every element. These values represent widely used practical guidance rather than universal legal pass criteria. A product design system may deliberately set larger minimums for its audience, brand typeface, device mix, or reading conditions.

Read the result as a screening decision

The result includes the submitted size, the selected content type, the minimum used for comparison, a pass-or-flag boolean, and a signed pixel difference. A difference of zero means the size lands exactly on the selected threshold and therefore meets this check. A negative difference shows how far below the guidance the current setting falls, while a positive difference shows the available margin. This direct comparison is useful in design-token reviews, component inventories, automated quality checks, and acceptance criteria because it converts an informal concern into a stable decision. However, passing should be treated as the beginning of accessibility evaluation rather than its end. Apparent size changes with the typeface, weight, letterforms, line height, display density, zoom, and surrounding layout. Text at 16 pixels can still be tiring if its contrast is weak or its line length is excessive. Conversely, a carefully drawn face may appear clearer than another face at the same nominal size. Use the flag to find likely problems quickly, then inspect the rendered component with real content and representative users or assistive settings.

Combine minimum size with resilient typography

Accessible typography must survive the ways people actually adapt a page. After resolving a flagged size, verify that text can zoom without clipping, controls can grow without losing their labels, and layouts reflow without forcing horizontal scrolling. Prefer relative CSS units in the implemented interface when they help preserve user settings, even though this checker accepts a pixel value for a clear and comparable calculation. Check contrast in every interactive state, including hover, focus, disabled, and error states. Give body text comfortable line spacing and line length, and avoid relying on tiny captions to carry essential instructions or legal choices. Button labels deserve special attention because a readable label can still fail when the clickable target is too small, focus is hard to see, or the accessible name is missing. The thresholds here are intentionally simple: 16 pixels for body text, 12 for captions, and 14 for button labels. That simplicity makes the tool suitable for repeatable screening, but context remains decisive. If your design serves readers with known low-vision needs, appears on distant displays, or operates outdoors, choose a larger house standard and treat this result only as a baseline warning system.