Audit vs Automated Scan
An accessibility audit is a thorough human evaluation of a website against Web Content Accessibility Guidelines (WCAG) criteria. An automated scan is a software check that loads pages and flags code-level issues it can detect. The two serve different purposes, and neither replaces the other.
| Key Point | What It Means |
|---|---|
| Coverage | Scans detect approximately 25% of accessibility issues. An audit evaluates the full scope of WCAG criteria. |
| Method | Scans analyze HTML, CSS, and ARIA attributes through software. Audits involve screen reader testing, keyboard testing, visual inspection, and code review by a trained evaluator. |
| Output | Scans produce a list of flagged code patterns. Audits produce a detailed report with specific issues, locations, and remediation guidance. |
| Speed | Scans complete in seconds or minutes. Audits take days or weeks depending on site size. |
What an Automated Scan Does
An automated scan loads a web page and checks the underlying code against a set of programmatic rules. It can identify issues like missing alternative text attributes, form inputs without labels, and incorrect heading order.
Scans work well for catching patterns that follow predictable code structures. They are fast, repeatable, and useful for monitoring a site over time on a recurring schedule.
The limitation is scope. Scans only flag approximately 25% of accessibility issues because most WCAG criteria require human judgment. A scan cannot determine whether alternative text accurately describes an image, whether a custom widget is operable with a keyboard, or whether content is understandable in context.
What an Audit vs Automated Scan Covers Differently
An audit is conducted by a trained accessibility professional who evaluates the site across the full range of WCAG conformance levels. The evaluator uses assistive technologies like NVDA, JAWS, and VoiceOver. They perform keyboard testing, screen reader testing, visual inspection, code inspection, and browser zoom evaluation at 200% and 400%.
The audit identifies issues that software cannot detect. These include problems with reading order, focus management in dynamic content, meaningful sequence of page elements, and whether interactive components communicate their state to assistive technology users.
Where a scan tells you a button exists, an audit tells you whether that button works for everyone.
How They Fit Together for ADA Compliance
Under ADA Title III, businesses have a general obligation to make their websites accessible. While Title III does not specify a technical standard, courts and the Department of Justice have consistently referenced WCAG 2.1 AA as the benchmark. ADA Title II, which applies to state and local government entities, directly references WCAG 2.1 AA.
Relying on scans alone leaves 75% of potential issues unidentified. Organizations that want to reduce legal risk pair recurring scans with periodic audits conducted by accessibility professionals.
Scans provide ongoing monitoring between audits. Audits provide the depth of evaluation that scans cannot reach. Each serves a distinct role in an accessibility program.
Cost and Timing Considerations
Most accessibility audits start at 1,000 dollars and range to 3,000 dollars depending on the size and complexity of the site. Scans are typically included as part of monitoring subscriptions or conducted through free browser-based tools.
Organizations often conduct scans on a weekly or monthly schedule and complete a full audit annually or after significant site changes. This pattern keeps monitoring costs low while providing thorough evaluation at regular intervals.
The cost difference reflects the depth difference. A scan is a quick automated check. An audit is a professional evaluation that identifies the full picture of a site’s WCAG conformance status.