HTML <bdo> Tag

The HTML <bdo> tag is used for over-riding the text direction in an HTML document.

This can be useful when displaying right-to-left written text (such as Hebrew, Arabic, Persian, Thaana, Urdu and other languages/scripts that are written from right to left) within left-to-right text (such as English) or vice versa.


The <bdo> tag is written as <bdo dir=""></bdo> with the relevant text inserted between the start and end tag. The value of the dir attribute must be either rtl or ltr (but not auto, which is allowed in other elements).

Like this:


Basic tag usage

Here's an example using English words written backwards to demonstrate how the tag works.

Persian Example

Here's an example using Persian (a right-to-left language). The first line doesn't use the <bdo> tag to specify right-to-left text, while the second one does. You can see that by adding <bdo dir="rtl">, the exclamation mark appears to the left of the phrase.

If the exclamation mark is part of the right-to-left phrase, it should appear to the left of it.


Attributes can be added to an HTML element to provide more information about how the element should appear or behave.

There are 3 kinds of attributes that you can add to your HTML tags: Element-specific, global, and event handler content attributes.

The <bdo> element accepts the following attributes.

Element-Specific Attributes

This table shows the attributes that are specific to the <bdo> tag/element.

dir** Although this element has no local attributes, you must use the dir global attribute. The dir attribute specifies the direction of the text:
  • ltr: Left to right
  • rtl: Right to left

This attribute must have the value ltr to specify a left-to-right override and with the value rtl to specify a right-to-left override.

Global Attributes

The following attributes are standard across all HTML5 elements. Therefore, you can use these attributes with the <bdo> tag , as well as with all other HTML tags.

For a full explanation of these attributes, see HTML 5 global attributes.

Event Handler Content Attributes

Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.

Below are the standard HTML5 event handler content attributes.

Again, you can use any of these with the <bdo> element, as well as any other HTML5 element.

For a full explanation of these attributes, see HTML 5 event handler content attributes.

Differences Between HTML 4 & HTML 5


To see more detail on the two versions see HTML5 <bdo> Tag and HTML4 <bdo> Tag. Also check out the links to the official specifications below.


Here's a template for the <bdo> tag with all available attributes for the tag (based on HTML5). These are grouped into attribute types, each type separated by a space. In many cases, you will probably only need one or two (if any) attributes. Simply remove the attributes you don't need.

Note that the <bdo> element does not actually have any local attributes (i.e. attributes that are specific to the element), but the following global attributes and event handlers are available to the element (and all other HTML elements).

For more information on attributes for this tag, see HTML5 <bdo> Tag and HTML4 <bdo> Tag.

* The dir global attribute must be specified on this element, with the value ltr to specify a left-to-right override and with the value rtl to specify a right-to-left override. The auto value must not be specified.

Tag Details

For more details about the <bdo> tag, see HTML5 <bdo> Tag and HTML4 <bdo> Tag.


Here are the official specifications for the <bdo> element.

What's the Difference?

W3C creates "snapshot" specifications that don't change once defined. So the HTML5 specification won't change once it becomes an official recommendation. WHATWG on the other hand, develops a "living standard" that is updated on a regular basis. In general, you will probably find that the HTML living standard will be more closely aligned to the current W3C draft than to the HTML5 specification.