Subtitle checker
Find subtitles that overlap, flash by too quickly, are too fast to read or have lines that are too long. Your inputs stay in this browser tab.
Your result
A little input. A useful result.
Your result will appear here.How to use subtitle checker
Find subtitles that overlap, flash by too quickly, are too fast to read or have lines that are too long. This free tool runs locally after you choose to start.
- Enter your own values, or start with the visible example.
- Adjust subtitles (srt, webvtt or lrc) as needed.
- Choose the action button. Review the result, then copy text or download a file when available.
- Choose Clear all when finished to remove inputs and results from the interface.
Limits, without the small print.
Paste up to 1 MB of SRT, WebVTT or LRC text; open a subtitle file in any text editor to copy it. Times are kept to the millisecond, and your text never leaves this browser tab.
One job runs at a time. You can cancel it; jobs stop after 30 seconds. Browser and device capabilities affect performance.
Understand the safeguards →What this tool does
The checker uses common broadcast guidelines: at least about a second on screen, no more than 20 characters per second and no more than 42 characters per row.
Example input
Subtitles (SRT, WebVTT or LRC): 1 00:00:01,000 --> 00:00:01,600 Too quick 2 00:00:01,500 --> 00:00:04,000 This line overlaps the one before it and is quite long
Example result
2 subtitle lines, ending at 00:00:04. 4 things to check: Line 1 (00:00:01) shows for less than a second. Line 1 (00:00:01) overlaps the next line. Line 2 (00:00:01) needs 22 characters per second; 20 or fewer is easy. Line 2 (00:00:01) has a row longer than 42 characters.
Questions people often ask.
Does subtitle checker upload my data?
No. This tool processes your input inside your browser. Your text and files are not sent to an application server. The static host receives page and asset requests; see our privacy explanation.
Is this tool free for work and study?
Yes. No account, paid API, usage subscription or watermark fee is required. You remain responsible for your content rights and checking results. Hosting providers and their free tiers are separate from this open-source software.
What should I check before relying on the result?
Paste up to 1 MB of SRT, WebVTT or LRC text; open a subtitle file in any text editor to copy it. Times are kept to the millisecond, and your text never leaves this browser tab. Review important outputs against the source, especially financial, legal, identity, medical and research calculations.
What is the difference between SRT and VTT?
Both store timed text. SRT is the most widely supported format for video players and editors, while WebVTT (.vtt) is the standard for web video. The converters keep every time to the millisecond.
How do I open an SRT file?
An SRT file is plain text. Open it in Notepad, TextEdit or any text editor, copy everything and paste it into the tool, then use the Download button to save the result.
How do I add subtitles to a video?
Use Add subtitles to video to burn them into the picture, or load the SRT file in your video player or upload it next to your video on YouTube so viewers can switch them on and off.