WCAG 2.0 · Level AA · Perceivable
1.4.3 Contrast (Minimum)
Text and images of text generally need a contrast ratio of at least 4.5:1. Large text has a lower minimum of 3:1. Exceptions include inactive interface components, pure decoration, invisible content, and text that is part of a logo or brand name.
Manual verification
How to validate 1.4.3 by hand
Measure text contrast in the actual rendered foreground/background pair, including states and overlays.
Start with the extension result
Reopen the reported URL and reproduce the same state (for example, after expanding a menu or submitting a form). Use the result’s Highlight action when available, or its affected-element details and CSS selector, to find the reported content. Apply the checks below to that content and its context. If the element or state has changed, rescan and record that difference before deciding whether the finding still applies.
- Identify text, placeholder text, text over images, and text in hover, focus, error, and disabled states.
- Measure the rendered colors with a contrast tool; use at least 4.5:1 for normal text and 3:1 for qualifying large text.
- Check gradients, transparency, images, and theme changes at every point where the text appears, rather than sampling one convenient pixel.
Evidence to record
Record the text, measured colors and ratio, text size/weight category, state, and any exception relied upon.
Scope and exceptions
Large text has a different threshold, and the criterion has exceptions such as inactive controls and logos. Automated sampling can be wrong when colors vary behind text.
Record the review outcome
- Confirmed: the recorded evidence shows the requirement is not met in the tested page state, and no applicable exception explains it.
- Not reproduced: the reported issue is absent in the current state. Record the URL, state, and affected element you checked; this does not prove other pages or states conform.
- Needs more review: evidence is incomplete, the content requires human judgment, or an exception is uncertain. Record what remains to be checked instead of treating it as a pass.
Why it matters
Sufficient contrast helps people distinguish text from its background, including people with low vision or reduced contrast sensitivity. Passing the ratio is one specific requirement and does not guarantee that text is comfortable for everyone to read.
Examples and distinctions
Normal text
Check the rendered foreground and background colors; the minimum ratio is 4.5:1.
Large text
The 3:1 threshold applies to large-scale text: at least 18 point, or at least 14 point bold, using the criterion's CSS pixel equivalents.
Text over an image
Check the contrast at the parts of the image behind the text where it appears. A single foreground and background color value may not represent the rendered result.