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Change Subtitle Frame Rate

Retime subtitles for a video playing at a different speed. Choose the source and target frame rates, then check the result on your own video.

Drop subtitle files here

SRT, VTT, ASS, SSA, SBV, or TXT files. Up to 50 at once.

Options

Positive = later; negative = earlier. Enter milliseconds (1500), seconds (1.5s) or a time (00:00:01,500).
Only needed for some older Windows players and for Excel.

Add a subtitle file first.

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Preview on your video (optional)

Choose a video from your device. Video and captions stay in this tab. MP4 (H.264) or WebM usually works; MKV and other codecs may not play in your browser.

Add a subtitle file first.

What this tool does

This tool retimes subtitles made for a video with a different frame rate, such as 23.976 fps subtitles on a 25 fps video. It multiplies every time by the exact ratio of the two frame rates and can add an offset afterwards. It changes the subtitle file only, not the video.

How to change subtitle frame rate

  1. Select Choose files to add subtitle files.
  2. Choose Source frame rate (subtitle) and Target frame rate (video). Select Custom for a decimal or fraction.
  3. Set Time shift if you also need a fixed delay. Optionally open Preview on your video (optional) to compare captions with your own video.
  4. Select Change frame rate, check the result and choose Download or Download all (ZIP).

Options explained

  • Source and target defaults are 23.976 (24000/1001) and 25. Other presets are 24, 29.97 (30000/1001), 30, 50, 59.94 (60000/1001) and 60. Swap the source and target selections to reverse a known conversion.
  • The formula is t′ = t × source FPS / target FPS + offset. Times are rounded to whole milliseconds internally. The extra Time shift defaults to 0.
  • Apply to selects all subtitles, a starting subtitle, a starting time or a closed range of original start times.
  • Subtitles before zero uses the same trimming/removal choices as the shifter. A subtitle with a positive duration that rounds below one millisecond gets a one-millisecond internal duration.

Example

With the default 23.976 → 25 conversion and no offset:

1
00:01:00,000 --> 00:01:02,000
The clock is running fast.

becomes:

1
00:00:57,542 --> 00:00:59,461
The clock is running fast.

Format notes and limits

  • Reads SRT, VTT, ASS, SSA, SBV and timestamped TXT; saves the same format in UTF-8. This changes subtitle times, not the video file.
  • ASS/SSA output rounds to 10 ms. Other supported timed formats keep milliseconds. Extreme custom ratios can lose more precision when reversed; keep your original file.
  • Video preview follows playback and seeking. A window with more than 500 subtitles shows the first 500 with a notice; this does not limit the downloaded file.
  • Up to 50 files, 20 MB per file and 200 MB in total. Resulting times must fit within 1000 hours.
  • Use Sync subtitles to fit two matching points, Shift subtitles for a fixed delay, or the subtitle converter to change formats.

Questions

How do I convert subtitles from 23.976 to 25 fps?

Set Source frame rate to 23.976 and Target frame rate to 25. Every timestamp is multiplied by 24000/1001 divided by 25. One minute becomes 57.542 seconds before any extra offset.

Which way round do the frame rates go?

Source is the speed the subtitle file was timed for. Target is the speed of your video. When a PAL version runs at 25 instead of 24 frames per second, the same footage plays faster, so its subtitle times need to shrink.

Will changing the FPS label fix subtitle timing?

This tool changes the actual start and end times of each subtitle. SRT and VTT use timestamps rather than a frame rate label, so changing the timestamps is what makes the correction.

Why does 23.976 use 24000/1001?

The 23.976 preset uses that exact fraction rather than rounding it to three decimal places. The 29.97 and 59.94 presets likewise use 30000/1001 and 60000/1001.

Can I use a custom frame rate and a delay together?

Yes. Choose Custom and enter a decimal or fraction between 0.1 and 1000 fps. The time shift is added after the speed change. Video capture sets that offset for the selected subtitle.

Will this fix every subtitle sync problem?

No. Use two-point sync when you know matching spoken lines but not the speed ratio. Use a fixed shift for a constant delay. A video with several cuts can need separate corrections.

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Last updated October 28, 2026 · Files never leave your browser.