ConvertAnyFilePrivate by design
Menu
Home/Guides/UTF-8 BOM subtitles
Subtitle encoding

What is a UTF-8 BOM in subtitle files?

A UTF-8 BOM is a short byte marker placed at the beginning of a text file. Modern software usually does not require it, but some older subtitle tools and Windows-oriented workflows use it as an encoding hint.

Quick answer

Leave UTF-8 BOM off unless the software that will open the subtitle expects it. If a subtitle displays non-ASCII characters incorrectly in a legacy tool, enabling BOM can sometimes improve encoding detection without changing the subtitle text itself.

What exactly is a UTF-8 BOM?

BOM stands for byte order mark. UTF-8 does not need byte ordering in the same way UTF-16 does, but the three-byte UTF-8 BOM is sometimes used to signal that a text file is encoded as UTF-8. It appears before the first visible character and is normally hidden by applications that understand it.

For subtitle files, the BOM does not change cue timing, dialogue, or format structure. It only changes the bytes at the beginning of the output file.

When can a BOM help?

  • An older subtitle editor guesses the wrong character encoding.
  • Accented, Cyrillic, Japanese, Korean, Chinese, or other non-ASCII text displays incorrectly in a legacy application.
  • A downstream workflow explicitly documents that UTF-8 with BOM is required.

For modern browsers, editors, and media tools, plain UTF-8 without BOM is often the cleaner default.

UTF-8 BOM is not the same as LF or CRLF

These settings solve different problems. BOM is an encoding marker at the beginning of the file. LF and CRLF describe how line breaks are stored throughout the text. A file can be UTF-8 with BOM and LF, UTF-8 without BOM and CRLF, or another valid combination.

Choose for the destination

Do not enable BOM just because it sounds safer. Use the simplest output that the destination accepts, and only add compatibility markers when the receiving software needs them.

How to control BOM when converting subtitles

  1. Open the Subtitle Converter.
  2. Add the subtitle file and let preflight detect the source encoding.
  3. Choose the output format.
  4. Enable UTF-8 BOM only when required by the destination.
  5. Choose LF or CRLF separately if the receiving workflow has a line-ending requirement.
  6. Convert and test the file in the target software.

Common UTF-8 BOM questions

Does BOM change subtitle content?

No. It adds an encoding marker before the text.

Is BOM required for UTF-8?

No. UTF-8 works without it. BOM is mainly a compatibility hint for certain software.

Can BOM fix broken characters?

Sometimes, if the receiving application is misdetecting UTF-8. It cannot repair text that was already decoded or saved incorrectly.

Should every SRT use BOM?

No. Only use it when the destination benefits from it.