Accessibility and SEO: where they overlap

Why accessibility matters

Around a quarter of people in the UK report a disability, according to the government's Family Resources Survey. Many more have temporary or situational difficulties: a broken arm, bright sunlight on a phone screen, a slow connection or simply ageing eyesight.

An accessible website is one that people can use regardless of these. It's also a legal matter. Under the Equality Act 2010, service providers must make reasonable adjustments for disabled people, and that's generally understood to include websites.

The widely used standard is the Web Content Accessibility Guidelines (WCAG), published by the W3C.

Where accessibility and SEO overlap

Search engines read pages in some ways like assistive technology does: through code and text, not visuals. So many accessibility improvements also help search.

Headings

Screen reader users often navigate by headings. Search engines use headings to understand page structure. A clear, logical heading structure helps both. See our heading structure guide.

Alt text

Alt text describes images for people who can't see them and for search engines. Describe what matters in the image, briefly. Use empty alt text for purely decorative images.

Link text

"Click here" and "read more" make no sense out of context. Screen reader users often list all links on a page. Descriptive link text such as "see our boiler servicing prices" helps them and tells search engines what the linked page is about.

Text, not images of text

Text inside images can't be read by screen readers unless described, can't be resized and isn't reliably understood by search engines. Use real text.

Captions and transcripts

Videos with captions help deaf and hard-of-hearing visitors and people watching with the sound off. Transcripts give search engines text to understand the video.

Page titles and language

Unique, descriptive page titles help screen reader users know where they are. Setting the page language, such as `lang="en-GB"`, helps screen readers pronounce words correctly.

Accessibility beyond SEO

Some accessibility needs don't directly affect search but matter just as much for customers:

• Colour contrast. Text must stand out clearly from its background. Pale grey on white fails many people.
• Keyboard access. Everything should work without a mouse, including menus and forms.
• Visible focus. People using keyboards need to see where they are.
• Forms with labels. Every field needs a proper label, not just placeholder text that disappears when typing.
• Clear error messages. Tell people what went wrong and how to fix it.
• No time limits that rush people, or a way to extend them.
• Readable content. Plain language and short sentences help everyone, including people with cognitive disabilities and those reading in a second language.
• Motion. Avoid auto-playing carousels and animations, or let people pause them.

How to check your site

• Automated tools. WAVE and Lighthouse's accessibility audit in Chrome catch common issues, such as missing alt text and low contrast. They find only some problems.
• Keyboard test. Put your mouse away and try to navigate your home page, menu and enquiry form using Tab, Shift+Tab and Enter.
• Zoom test. Zoom the browser to 200% and check nothing breaks or disappears.
• Screen reader test. Try VoiceOver on a Mac or iPhone, or NVDA on Windows, on your main pages.
• Ask real users. If you can, get feedback from disabled people who use your type of service.

A worked example

A small physiotherapy practice in Norwich had an online booking form with fields labelled only by grey placeholder text, a pale blue button on a white background and a cookie banner that trapped keyboard users.

The practice added visible labels above each field, made error messages specific ("Please enter a phone number we can call you on"), changed the button colour to meet contrast requirements and fixed the cookie banner so it could be closed with the keyboard. It also added alt text to clinician photos and replaced "click here" links with descriptive ones.

Several patients mentioned the booking form was easier. The improvements also made the pages cleaner and clearer for search engines.

Documents and PDFs

Price lists, menus, forms and brochures are often uploaded as PDFs. Many are scanned images that screen readers can't read at all, and they're awkward on phones for everyone. Where the information matters, put it on an ordinary web page instead. It'll be easier to update, easier to read on a small screen and easier for search engines to understand. If you must use a PDF, create it from a text document with headings and alt text rather than scanning a printout.

Overlays aren't a fix

Some companies sell accessibility overlays: scripts that claim to make a site accessible automatically. Many disabled users and accessibility experts say they don't fix underlying issues and can make things worse. Fixing the site itself is the reliable approach.

Make it part of your routine

Accessibility isn't a one-off project. Every new page, image, video and form should be accessible from the start. Add a few checks to your publishing process: alt text, headings, link text, contrast and keyboard access. It takes minutes once it's a habit.