DCMP Captioning Key

October 15, 2023


Captioning Key refers to the guidelines developed by the Described and Captioned Media Program (DCMP), which is funded by the U.S. Department of Education. It is a set of guidelines specifically focused on closed captioning for educational and training materials.

While DCMP Captioning Key guidelines are not legally binding, they are widely recognized and followed by many educational institutions in the United States. The basic principles are largely consistent with the FCC rules. However, Captioning Key rules contain more detailed specifications and guidelines on what constitutes ‘good captions’.

Closed Caption Quality

Captioning Key provides detailed recommendations and specifications for creating high-quality closed captions that enhance accessibility for people with hearing disabilities.

These guidelines cover various aspects of closed captioning to ensure accuracy, readability, synchronization, and comprehension. Here are some key areas that contribute to the quality of closed captions:



Closed captions should accurately represent the spoken content, including dialogue, important sound effects, and relevant non-speech information. The captions should reflect the intended meaning and context of the audio.



Closed captions should be properly timed and synchronized with the corresponding audio. They should appear and disappear at appropriate times, allowing viewers to follow the captions in real-time with the spoken words.



Closed captions should be presented in a way that is easy to read and comprehend. This includes using legible fonts, appropriate text sizes, and suitable contrast with the background. Captions should be free from spelling and grammatical errors.



Captions should be placed at the bottom of the screen, unless there are visual obstructions or essential on-screen elements that require adjustments. The captions should not overlap with important visuals or text.


Consistent Formatting

The formatting should be consistent and clear, with appropriate use of capitalization, punctuation, and line breaks. By maintaining consistent formatting, viewers can easily recognize and understand the different elements of the captions.


Presentation of Speaker Information

When multiple speakers are involved, captions should clearly identify each speaker to aid comprehension. This can be achieved through the use of speaker labels, such as speaker names or other visual cues.

Formatting Guidelines

Captioning Key provides detailed guidelines for formatting closed captions to ensure readability and comprehension. Here are some key formatting guidelines outlined in the Captioning Key.


Caption Lines and Duration

  • There should be no more than 2 lines of text per screen. Lines should be limited to 32 characters or less, including spaces. Text should be centered on the screen and left-aligned. A new sentence should preferably start on a new line, unless it is very short.
  • The duration of the captions should be adjusted to match the spoken dialogue. Captions should appear and disappear at appropriate times, with consideration for natural reading speed and viewers’ ability to process the information.

Line Breaks and Punctuation

  • Lines of text within captions should be broken logically and at natural pause points in the dialogue. Breaking lines in a way that reflects the spoken rhythm and phrasing helps viewers follow the captions more easily.
  • Punctuation marks, such as commas, periods, and question marks, should be used appropriately within captions to convey the intended meaning and aid comprehension. They should align with the spoken words.

Fonts and Text Size

  • Captioning Key suggests using sans-serif fonts for captions, as they are generally easier to read. Commonly used sans-serif fonts include Arial, Helvetica, and Verdana. The thickness of the font should be average, not too thin or too heavy.
  • The text size of the captions should be large enough to ensure readability on different screen sizes. The recommended minimum text height is approximately 1/16th of the screen height.

Text and Background Color

  • Captions should have sufficient contrast with the background to ensure legibility. Light-colored text is typically used on a dark background, while dark-colored text is used on a light background. The Captioning Key recommends avoiding color combinations that result in low contrast.
  • A solid background behind the text can enhance readability by providing a clear contrast. The Captioning Key suggests using a semi-transparent rectangular background for captions to help separate the text from the video content.