Accessibility Rule: Image buttons must have alternative text

About This Accessibility Rule

An <input type="image"> element renders an image that functions as a submit button. Unlike standard <input type="submit"> buttons that display their value attribute as visible text, image buttons rely entirely on their visual appearance to communicate purpose. This means assistive technologies have no way to determine the button’s function unless you explicitly provide alternative text.

This is a critical accessibility barrier for several groups of users. Blind and deafblind users who rely on screen readers will hear something generic like “button” or, worse, the image file name (e.g., “btn_submit_v2.png”), which provides no useful information. Users with low vision who use screen magnifiers in combination with screen readers are similarly affected. Without a clear accessible name, these users cannot confidently interact with forms.

This rule relates to two WCAG success criteria at Level A — the minimum conformance level:

WCAG 1.1.1 (Non-text Content): All non-text content must have a text alternative that serves the equivalent purpose. An image button is non-text content, so it needs alternative text.
WCAG 4.1.2 (Name, Role, Value): All user interface components must have a programmatically determinable name. Buttons must expose their name to assistive technologies.

This requirement is also mandated by Section 508, EN 301 549, and the Trusted Tester guidelines.

How to fix it

Provide a non-empty accessible name for every <input type="image"> element using one of these methods:

alt attribute (preferred): Add an alt attribute that describes the button’s action. This is the most straightforward and widely supported approach.
aria-label attribute: Set an aria-label with a concise description of the button’s action.
aria-labelledby attribute: Reference the id of another visible element that describes the button’s action.

Writing effective alternative text

The alternative text for an image button should describe the action the button performs, not the image itself. Ask yourself: “What happens when the user clicks this button?” The answer is your alternative text.

✅ “Submit”, “Search”, “Add to cart”, “Log in”
❌ “Green arrow icon”, “button.png”, “click here”

Avoid filler words like “image of” or “button” — assistive technologies already announce the element’s role as a button.

Important: Simply placing text next to the image button in the HTML is not sufficient. Screen readers need a programmatically associated label, not visually adjacent text. Nearby text cannot be reliably determined as the button’s label by assistive technologies.

Examples

Incorrect: missing alternative text

The image button has no alt, aria-label, or aria-labelledby attribute. A screen reader might announce this as “submit.png button” or just “button.”

<form action="/search">
  <label for="query">Search</label>
  <input type="text" id="query" name="q">
  <input type="image" src="search-icon.png">
</form>

Incorrect: empty `alt` attribute

An empty alt attribute tells assistive technologies to ignore the element, effectively hiding the button entirely.

<input type="image" src="search-icon.png" alt="">

Correct: using the `alt` attribute

<form action="/search">
  <label for="query">Search</label>
  <input type="text" id="query" name="q">
  <input type="image" src="search-icon.png" alt="Search">
</form>

Correct: using `aria-label`

<input type="image" src="submit-arrow.png" aria-label="Submit order">

Correct: using `aria-labelledby`

The aria-labelledby attribute points to the id of a visible element. Make sure the referenced element exists and is not hidden with display: none or aria-hidden="true".

<h2 id="checkout-heading">Complete your purchase</h2>
<form action="/checkout">
<!-- form fields -->

  <input type="image" src="checkout-btn.png" aria-labelledby="checkout-heading">
</form>

What the rule checks

This rule verifies that every <input type="image"> element has a discoverable accessible name. It fails if the element has no alt, aria-label, or aria-labelledby attribute, or if those attributes are empty or resolve to an empty string.

Learn more: