Subtitle timing best practices
Timing is the part of subtitle work that separates a professional file from an amateur one. This guide covers the timing rules that actually matter — not the ones in legacy style guides that were designed for 1970s broadcast televisions.
Minimum cue duration
A cue should be visible for at least 1 second. Below that, most viewers cannot read the line even if it is short. The theoretical minimum is one frame, but practical human reading requires at least 500ms, and comfortable reading requires 1000ms+ for anything more than a single word.
For dialogue cues that contain more than two or three words, aim for a minimum of 1.5 seconds.
Maximum cue duration
A cue should not stay on screen for more than 6–7 seconds. Beyond that, viewers stop paying attention to the text and may even forget it is there. If a cue would need more than 6 seconds, split it into two cues at a natural pause in the dialogue.
There are exceptions: a cue that accompanies a long silent shot, or a cue that is intentionally slow (e.g. a poetic title). But for standard dialogue, 6 seconds is the practical upper limit.
Lead-in time
A cue should appear slightly before the corresponding dialogue starts, so the viewer's eyes have time to reach the text. The standard is 100–200 milliseconds of lead-in. In a fast-moving action scene, lead-in can be shorter (50ms). In a slow dialogue scene, it can be longer (250ms).
Lead-out time
A cue should disappear slightly after the corresponding dialogue ends, so the viewer can finish reading the last word. The standard is 100–300 milliseconds of lead-out. If a cue is short and dense, give it more lead-out. If the next cue is coming quickly, give it less.
Gaps between cues
Cues should not run into each other. Leave a small gap — typically 2–3 frames at 24fps (approximately 80–120ms) — between the end of one cue and the start of the next. This visual break helps the viewer register that one cue has ended and another has begun.
In continuous dialogue (e.g. a fast back-and-forth conversation), you can reduce the gap to 1 frame or eliminate it entirely. But small gaps improve readability in most content.
Overlapping cues
Cues should generally not overlap. If two cues overlap, the viewer sees two sets of text at the same time, which is confusing and often unreadable.
The exception is deliberate overlap: two characters talking simultaneously, a voice-over on top of on-screen dialogue, or a song lyric overlaid on dialogue. In these cases, either merge the two cues into one with two lines of dialogue (prefixed with character names if useful), or accept the overlap for the creative effect.
Reading speed targets
Reading speed is measured in characters per second (CPS). Common guidelines:
- Netflix: 20 CPS maximum for adult content, 17 CPS for pre-lingual deaf audiences, 12 CPS for children.
- BBC: 160 words per minute for adults, roughly equivalent to 17–18 CPS.
- General consensus: aim for 15–17 CPS for average content.
If your subtitle exceeds the target CPS, it will feel rushed. Options to fix:
- Split the cue into two cues at a natural pause.
- Shorten the dialogue (subtitle is not the same as transcript — condense where possible).
- Extend the cue duration slightly (if there is room without overlapping).
Cue consistency
Within a scene, cues should feel like they belong to the same rhythm. If one cue is on screen for 4 seconds and the next for 0.5 seconds, the rhythm feels jarring. Try to keep durations within a reasonably consistent range unless the source audio has been intentionally irregular.
Dialogue vs sound effects
Most subtitle files contain dialogue only. If you are producing subtitles for the deaf and hard-of-hearing (SDH), sound effects and speaker identification are added:
- Sound effects: in square brackets, e.g.
[door slams]. - Speaker labels: prefixed to dialogue, e.g.
- MARY: Hello.. - Musical cues: in italics or brackets, e.g.
[soft piano].
SDH timing follows the same rules, but cues may need slightly more lead-out time to accommodate the extra reading.
Validating timing
Use the SRT Validator and Duration Report to catch outliers. The validator flags cues under 500ms (too short) and over 10s (too long). The duration report gives you averages and extremes so you can see whether the file is well-timed overall.