Subtitle FPS Converter
Fix subtitles that drift out of sync by converting timing between different frame rates (23.976, 24, 25, 29.97, 30 fps). Free and private.
What is FPS Mismatch and How to Fix It
Frame rate mismatch happens when a subtitle file was created for a video at one frame rate, but you are using it with a video at a different frame rate. Unlike a simple delay (constant offset), an FPS mismatch causes the subtitle sync to drift gradually — it may be fine at the start but become several seconds off by the end of the video.
Common FPS mismatch scenarios
- 23.976 vs 25 fps — the most common mismatch. A 23.976 fps source rip often accompanies subtitles timed to 25 fps PAL releases (or vice versa).
- NTSC (29.97) vs PAL (25) — television shows distributed across regions often have both NTSC and PAL versions with different frame rates.
- 24 vs 23.976 — cinema 24fps masters vs NTSC pulldown versions.
How FPS conversion works
Each timestamp is multiplied by the ratio of source FPS ÷ target FPS. For example, converting from 25 fps to 23.976 fps multiplies all timestamps by 25/23.976 ≈ 1.0427, making them slightly later to match the slower frame rate.
Frequently Asked Questions
How do I know if my problem is an FPS mismatch or a simple delay?
Check the sync at the beginning and end of the video. If the error is roughly the same offset throughout, it is a simple delay — use the Delay Fixer. If the error gets worse over time (starts at 0.5s off, ends at 5s off), it is an FPS mismatch.
What FPS is a typical downloaded subtitle?
Most English subtitles on sites like OpenSubtitles are timed to either 23.976 fps (NTSC DVD/Blu-ray) or 25 fps (PAL DVD). NTSC is the most common for North American releases.
My video is 60fps — can I convert to that?
Yes, use the Custom FPS option and enter 60. The conversion math is the same regardless of frame rate.