HTML · ATTRIBUTE

HTML size Attribute: Input Width and Select Listbox

Last reviewed November 4, 2026

The size attribute sets the visible width in characters of an input with type text, search, tel, url, email or password. It takes a positive integer and defaults to 20. On a select, size sets the number of visible rows; a size greater than 1 or the multiple attribute displays a listbox. Size does not apply to input types such as number, date or checkbox.

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Minimal snippet

size-example.html

<label for="username">Username</label>
<input type="text" id="username" name="username" size="10">
<label for="topic">Topic</label>
<select id="topic" name="topic" size="4">
  <option value="sales">Sales</option>
  <option value="support">Support</option>
  <option value="billing">Billing</option>
  <option value="other">Other</option>
</select>

Copy-paste code

HTML size attribute code you can paste today.

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size-attribute.html

<form action="https://splitforms.com/api/submit" method="POST">
  <input type="hidden" name="access_key" value="YOUR_ACCESS_KEY">
  <label for="username">Username</label>
  <input type="text" id="username" name="username" size="10" maxlength="30" required>
  <label for="topic">Topic</label>
  <select id="topic" name="topic" size="4">
    <option value="sales">Sales</option>
    <option value="support">Support</option>
    <option value="billing">Billing</option>
    <option value="other">Other</option>
  </select>
  <input type="checkbox" name="botcheck" style="display:none">
  <button type="submit">Send</button>
</form>

Attributes · size

Which attributes affect size?

Use size for visible dimensions, maxlength for input length and CSS for layout.

HTML size attribute attributes and what each one does
Attribute	What it does	Docs
`size`	A positive integer: the approximate visible character width of a supported input, or the number of visible rows in a select.	MDN
`maxlength`	Limits the length of a supported input's value; size controls its visible width instead.	MDN
`multiple`	Allows multiple selections and displays a select as a listbox, including when size is 1.	MDN
`width (CSS)`	CSS width overrides the input width suggested by size and offers more control over layout.	MDN

Common mistakes

Size attribute mistakes to avoid

Separate the control's appearance from its value and selection behavior.

Size is not maxlength
A user can enter more characters than the visible width. Use maxlength to limit the input value's length.
CSS width wins
An explicit CSS width overrides the width suggested by size. Use CSS for responsive or precise control of the input's layout.
Multiple still displays a listbox
A select with multiple remains a listbox even with size="1". Size sets the visible row count, not whether multiple choices are allowed.

Sources: WHATWG HTML Standard: input size · MDN: size attribute

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The HTML size attribute example below is a complete, working form — paste it into any HTML page and it submits, no edits to the markup required.

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Unlike a static reference snippet, this size form actually sends data to a free splitforms backend, with spam filtering built in.

How it works

How to add HTML size attribute to any page.

Copy the html size attribute example, drop in your free access key, and paste it into any page — submissions start landing in your dashboard.

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Copy the HTML size attribute example below.

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Questions

HTML size attribute questions, answered.

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What does size do on an input?

On text, search, tel, url, email and password inputs, size sets the approximate visible width in characters. It must be a positive integer and defaults to 20; it does not apply to number, date or checkbox inputs.

What is the difference between size and maxlength?

Size controls the visible width of a supported input. Maxlength limits the length of its value; size alone does not prevent typing more characters.

How does input size compare with CSS width?

Size suggests a visible width in characters, while CSS width controls layout in units such as pixels or percentages. An explicit CSS width overrides size.

How do I show all options of a select?

Set size to the number of options, for example size="4" for four options. The list can scroll when there are more options than visible rows; CSS and browser rendering can affect the final appearance.

Is size submitted with the form?

No. Size controls presentation and is not submitted. An enabled named input sends its name and value; a select sends the name and selected option value for each selected option.

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