Subtitle FPS Converter
Adjust SRT or VTT timing for a change in playback speed. Choose source and target frame rates, preview the result and download in the original format.
Frame rate of the video these subtitles were timed for.
Frame rate of the video you want to match.
Use this tool when a frame-rate change also changes playback speed.
Subtitle Preview
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Choose valid source and target FPS to update the result. Any previous preview is retained; its download is unavailable.
How to convert subtitle FPS
- Choose your subtitle. Select or drop one SRT or VTT file. If asked, check the decoded text and confirm its encoding.
- Choose both frame rates. Select the source and target FPS, or enter custom decimals. The result updates automatically when both values are valid. Use this for a playback-speed change.
- Download or preview. Save the result using the download above the preview. Output stays in the input format. You can also compare Original and Converted, and review any repairs, skipped entries or format changes.
Format notes
New time = original time × source FPS ÷ target FPS. Presets 23.976, 29.97 and 59.94 use 24000/1001, 30000/1001 and 60000/1001. Custom decimals use the value you enter. Times round once at export to milliseconds; positive durations that round to zero are extended to 1 ms and reported. Output keeps SRT or VTT, text formatting and valid VTT settings, styles, regions and notes; inline times scale with cues. Changed timing removes external HLS timestamp mapping. Output is UTF-8 without a BOM.
Frequently asked questions
What do Source FPS and Target FPS mean?
Source FPS is the frame rate of the video version these subtitles were timed for. Target FPS is the frame rate of the version you want to match. SRT and VTT timestamps do not reliably identify that video frame rate; check the video versions rather than guessing.
Should I use this for every frame-rate change?
Use this when the change also changes playback speed. A conversion that duplicates or drops video frames while keeping the same speed and duration usually does not need subtitle timing conversion. This tool does not read or transcode video.
How is subtitle timing calculated?
Each time is multiplied by source FPS and divided by target FPS. For example, 25 to 24 changes an original 10 seconds to 10.417 seconds after rounding. Every update starts from the original subtitle, so changes do not compound.
Why does a preset differ from the same custom decimal?
The 23.976 preset means 24000/1001 FPS. Entering 23.976 under Custom uses exactly that decimal, which is slightly different. The same distinction applies to 29.97 and 59.94. Select the value that matches your video.
Why is downloading disabled after I change FPS?
Choose both source and target FPS to generate a result automatically. Valid changes update the result; downloading is unavailable while an update is pending or a value is invalid. The previous preview stays visible and is marked as a previous result. Custom FPS accepts ordinary decimals from 1 to 240 with up to 6 decimal places.
Is my subtitle uploaded?
Your subtitle file is read and processed in your browser. Its content and filename are not uploaded to a server. The page still requests the resources needed to run the website.