Free Online Subtitle Resyncer
Fix out-of-sync subtitles instantly. Whether your subtitles are appearing too early, too late, or slowly drifting apart due to frame rate mismatches, TheSubAI helps you synchronize them perfectly with your video. Supports SRT, VTT, ASS, and other major formats.
How to Sync Subtitles Online?
Correcting subtitle timing takes just a few seconds. Choose the method that fits your problem:
Method 1: Time Offset (For Constant Delay)
Use this if the subtitle is consistently late or early by the same amount of time throughout the whole movie.
- Subtitles appear BEFORE audio: Use a Positive (+) value (e.g., +1s or +1000ms) to push them forward.
- Subtitles appear AFTER audio: Use a Negative (-) value (e.g., -1s or -1000ms) to pull them back.
Method 2: FPS Correction (For Drifting Subtitles)
Use this if the subtitles start in sync but get progressively worse as the video plays. This happens when the subtitle frame rate doesn't match the video file (e.g., Blu-ray vs. DVD).
Supported FPS Conversions:
- 23.976 (NTSC Film): The standard for most Hollywood movies and Blu-rays.
- 25 (PAL): The standard for European TV and DVDs.
- 24 (Film): True cinema frame rate.
- 29.97 (NTSC) & 30 FPS: Common for US TV broadcasts.
Why use TheSubAI Resyncer?
- Permanent Fix: Unlike media players (VLC, MPC-HC) that only adjust sync temporarily, we generate a new file with permanently corrected timestamps.
- Precision Control: Adjust timing down to the millisecond.
- Smart FPS Conversion: We mathematically recalculate every timestamp to match the target frame rate perfectly.
Free Online Subtitle Resyncer - FAQ
If the text appears after the audio, you need to make it appear earlier. Enter a negative value like -2000ms (which equals 2 seconds) in the Time Offset box.
23.976 FPS is standard for movies (NTSC/Blu-ray), while 25 FPS is standard for European TV (PAL). If you use a subtitle made for a Blu-ray on a PAL DVD rip, the audio and text will drift apart by several seconds by the end of the film.
Yes. TheSubAI generates a new subtitle file with permanently corrected timestamps that you can use on any device, TV, or upload to YouTube.