Netflix Subtitle Checker

The Netflix Subtitle Checker reads the SRT you paste into the SRT Content box and audits every cue against four broadcast-style limits: at most two lines, at most 42 characters per line, a reading speed at or below 21 characters per second, and a minimum display time of one second. You get a plain-text report naming each offending cue, or a single pass message, downloadable as .txt.

Strict OTT platforms reject deliveries on exactly these grounds, and a rejection usually costs a day. Subtitle vendors, QC operators and freelance translators need to know before an asset goes out whether a cue runs three lines or flashes past at 28 characters per second. Reading speed in particular is invisible in a text editor.

The checker parses the SRT into timed cues, splits each cue on newlines to count lines and measure their lengths, computes characters per second from the text length over the cue duration, and converts the start-to-end gap into seconds for the minimum test. Every failure is reported separately with the cue index and the measured number, so a cue that is both too long and too fast produces two clear entries.

These thresholds mirror common OTT guidance rather than any one company's current contract, so confirm the exact figures against your platform spec. The tool is read-only and nothing you paste is uploaded.

• Line count enforcement: Any cue containing more than two lines is flagged by number, catching the three-line blocks that slip in when a translator expands an English source into a longer language.
• Per-line character limit: Each line is measured individually against the 42-character ceiling and reported with its actual length, so you know exactly how much has to come out.
• Reading speed calculation: Characters per second are computed from the cue text and its duration and flagged above 21 cps, exposing cues that are technically correct but impossible to read in the time given.
• Minimum duration test: Cues shorter than one second are listed with their duration to two decimal places, which catches the flash frames that survive an automatic split.
• Cue-numbered report: Every issue names the cue index, so you can jump straight to the problem in your subtitle editor instead of hunting through the file.
• Non-destructive by design: The checker only inspects the SRT Content you paste and never modifies it, so your master file stays exactly as your editor left it.
• Clean-pass confirmation: When no cue breaks a rule you get an explicit pass message, which is a useful thing to keep with a delivery record.
• Runs locally: Parsing and measurement happen in your browser, so confidential pre-release scripts never leave your machine.

1. Paste your finished subtitle file into the SRT Content box, or press Load sample to see how an over-length line is reported.
2. Press Run to produce the spec report, which appears as either a numbered list of issues or a single pass message.
3. Work down the list from the top, noting each cue number and which of the four rules it broke.
4. Open the flagged cue numbers in your subtitle editor and shorten the text, split the cue or extend its out-time as appropriate.
5. Pay particular attention to any cue flagged for both characters per second and duration, since extending the out-time usually fixes both at once.
6. Paste the corrected file back in and run the check again until you get the clean-pass result.
7. Download the final report as a .txt file and keep it with the delivery as evidence that the asset was QC'd.

Example 1 - a line that is too long and too fast. The text reads fine on the page but breaks two rules at once.

Input cue:
7
00:01:04,000 --> 00:01:05,200
The committee reconvened at dawn to review the amended proposal.

Report:
Cue 7: 63 chars/line (max 42).
Cue 7: 52.5 cps (max 21).

Example 2 - a three-line cue and a flash frame. Splitting the first and lengthening the second is the usual fix.

Report:
Cue 12: more than 2 lines.
Cue 19: 0.64s (min 1s).

After fixing:
Passes Netflix-style spec.

Each entry gives the measured number, not just a warning, so you know whether a cue needs a small trim or a genuine re-split before redelivery.

• Avoid a rejected delivery: Catching over-length lines and impossible reading speeds before you ship saves the day or more that a platform QC bounce typically costs.
• Genuinely readable captions: Enforcing reading speed and minimum duration means viewers can finish a line before it disappears, which is the whole point of the spec.
• Faster fixes: Because every issue names a cue number and a measured value, you go straight to the problem rather than proofreading the entire file line by line.
• A record you can hand over: The downloadable report doubles as QC documentation, useful when a client asks what checks were run before delivery.
• Better accessibility: Cues that respect line and speed limits serve deaf and hard-of-hearing viewers far better than a technically valid file crammed with unreadable text.
• Confidential scripts stay private: Since the audit runs in your browser, pre-release dialogue is never uploaded to a checking service.