SubCaptions

Subtitle specs that festivals and platforms expect

There is no single "festival format," but festivals, broadcasters, and streamers nearly all follow the same readability rules, most famously codified in the Netflix and BBC style guides. Here is the plain-English checklist. The SubCaptions editor applies the line-length and reading-speed limits below as you type.

The core rules

Max 2 linesNever more than two lines of text on screen at once.
Max 42 characters / lineFor Latin-script languages. Prefer one line unless it exceeds 42.
Reading speed ≤ 20 cpsUp to 20 characters per second for adult content, 17 for children's.
Duration 0.83s to 7sNo subtitle shorter than 5/6 of a second or longer than 7 seconds.
No overlapsCues must not overlap, and need a small gap (about 2 frames) between them.
Accurate timecodesStart and end times match the speech. Standard .srt or .vtt.

For accessibility (SDH)

If you are making captions for the deaf and hard of hearing, also identify speakers (e.g. JANE:) and describe meaningful sound, like [engine sputtering] or [tense music]. Many broadcasters and US compliance rules (FCC/ADA) expect this.

What festivals actually want

It varies by festival, so always read each one's submission page. In practice, almost all accept one of two things: a standard .srt file (exactly what SubCaptions exports), or a screener with the subtitles burned in (rendered permanently into the picture); SubCaptions exports the .srt, and burned-in export is listed as coming soon. Non-English-language films almost always need English subtitles to be considered. Getting line length and reading speed wrong is the most common reason files get flagged, which is why the rules above matter.

How SubCaptions helps

The editor caps each line at 42 characters and two lines automatically, and warns you when a caption runs faster than 20 characters per second. It does not check caption duration, overlaps, or gaps between captions, so check those against the rules above before you submit. Export a standard .srt or .vtt, then translate it or, on a Team plan, hand the project to a translator.

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Sources: Netflix English Timed Text Style Guide (42 chars/line, 2 lines, 20 cps adult / 17 cps children, 5/6s to 7s duration); BBC Subtitle Guidelines. Always confirm each festival's own submission requirements.