Subtitle Sync Tool — Fix Timing Online Free

Q: How do I know how many milliseconds to offset?

Play your video and note the exact time when a character starts speaking. Then check the timestamp of the corresponding subtitle line in your file. The difference between these two times, in milliseconds, is your offset. For example, if the actor speaks at 00:01:05.000 but the subtitle shows at 00:01:03.000, you need an offset of +2000 milliseconds.

Key Takeaways

Fix out-of-sync subtitles instantly in your browser. Upload your SRT or VTT file, adjust the timing offset, and download the corrected version. No software needed.

Drop your SRT or VTT file here

or click to browse

Offset (milliseconds)

How to Sync Subtitles

Out-of-sync subtitles are one of the most common frustrations for anyone watching foreign films, streaming content with separate subtitle files, or using fan-made translations. The text appears too early or too late, breaking the viewing experience and making it difficult to follow dialogue. Understanding why sync issues happen and how to fix them will save you time and help you enjoy your content without distraction.

Why Subtitles Go Out of Sync

Subtitle timing problems typically originate from one of several sources. The most frequent cause is a mismatch between the video version and the subtitle version. A subtitle file timed for a Blu-ray release may not match a streaming version of the same film because streaming platforms sometimes trim intro sequences, adjust credits, or apply slight edits for content rating compliance. Even a difference of a few seconds at the start of the film can throw every subtitle line off for the entire duration.

Encoding and frame-rate differences can also cause drift. A subtitle file created for a 23.976 fps version of a video will gradually fall out of sync when played against a 25 fps PAL encode. This type of drift is harder to notice at first because it starts small and accumulates over time — subtitles might be perfect at the beginning and several seconds off by the end of the film.

How to Identify the Correct Offset

The simplest method is to play your video and watch for the first clearly identifiable line of dialogue. Note the exact timestamp when the actor begins speaking, then open your subtitle file and find the timestamp of the corresponding subtitle entry. The difference between these two values, in milliseconds, is your offset. If the subtitle appears too early, you need a positive offset to delay it. If it appears too late, you need a negative offset to advance it. For example, if the actor speaks at 00:01:05.000 but the subtitle displays at 00:01:03.000, you need to apply an offset of +2000 milliseconds.

Using the SoftSubs Sync Tool

The process is straightforward. Drag your SRT or VTT file into the upload zone above, or click to browse and select it from your device. Once uploaded, the tool parses every subtitle entry and displays a preview table showing entry numbers, start times, end times, and text content. Enter your desired offset in the milliseconds input field — positive values to delay, negative to advance — and click Apply Offset. The preview table updates immediately so you can verify the corrected timestamps before downloading. When you are satisfied, click Download Synced File to save the corrected subtitle to your device.

Tips for Accurate Syncing

Always verify your offset using a line of dialogue near the middle of the film, not just the beginning. This confirms the offset is constant and not a case of progressive drift. If possible, check a line near the end as well. If the sync is correct at the start but drifts by the end, you may be dealing with a frame-rate mismatch rather than a simple offset problem, which requires a different approach such as re-timing or using our subtitle editor for per-line adjustments. Keep your offset values in round numbers when possible — most sync issues between video versions result in offsets that are exact seconds (multiples of 1000 milliseconds), so try those first.

Common Sync Problems

Constant Offset vs. Variable Drift

The most important distinction in subtitle sync issues is whether the problem is a constant offset or a variable drift. A constant offset means every subtitle is shifted by the same number of milliseconds — this is the most common scenario and the easiest to fix. It typically happens when subtitle files are timed for a different cut of the video that has extra or missing content at the beginning, such as a studio logo, a different opening sequence, or a previously-on recap segment. The SoftSubs Sync Tool handles constant offsets perfectly: enter the value, apply it, and every timestamp shifts uniformly.

Variable drift, on the other hand, means the offset grows or shrinks over time. This usually results from a frame-rate mismatch between the video and the subtitle file. For instance, a subtitle file authored at 25 fps will accumulate roughly four seconds of drift per hour when played against a 23.976 fps video. Variable drift cannot be fixed with a single offset value. Instead, you need to re-time the subtitle file to match the target frame rate, or manually adjust individual timestamps using the subtitle editor.

Scene-Based Sync Issues

Some video releases insert or remove scenes compared to the version the subtitles were created for. A director’s cut might include additional scenes that push later dialogue forward, while a TV broadcast version might cut scenes for runtime. In these cases, the subtitles will be perfectly synced for part of the film and then suddenly jump out of alignment at the point where content differs. Fixing scene-based sync requires splitting the subtitle file at the divergence point and applying different offsets to each segment. You can use the SoftSubs editor to select and adjust specific ranges of entries.

Multi-Segment Drift

In rare cases, a subtitle file may have multiple sync issues throughout — for example, correct at the start, off by two seconds after an ad break, and off by four seconds after a second ad break. This commonly occurs with subtitle files created for TV broadcasts that include commercial breaks when used with commercial-free streaming versions. The solution is to identify each break point and apply separate offsets to each segment. For straightforward two-segment fixes, you can process the file twice: first apply an offset to get the second half correct, manually fix the first half in the editor, or use our merge tool to combine separately corrected segments.

More Subtitle Tools & Resources

The sync tool is one part of the SoftSubs platform. Find subtitles, translate them, convert formats, and more.

Subtitle Library

Find correctly synced subtitles. Browse 10M+ verified files for movies, TV shows, YouTube, and podcasts in 200+ languages.

Explore Library

Format Converter

Convert between SRT, VTT, ASS, and SUB formats instantly. Upload any supported file and download the converted result in seconds.

Convert Now

Merge Tool

Combine multiple subtitle tracks into one file. Create bilingual subtitles or join split files with automatic timing alignment.

Merge Files

Subtitle Editor

Edit subtitle text and individual timestamps directly in your browser. Fix typos, adjust lines, and preview changes in real time.

Open Editor

AI Translation

Translate any subtitle file into 200+ languages using AI with cultural localization. Community editors refine every result for accuracy.

Start Translating

Quality Ratings

Every subtitle is scored for sync accuracy, translation quality, readability, and cultural nuance. Trust what you download.

Learn More

Request Board

Can’t find the subtitles you need? Post a request and let our community of 500,000+ contributors help. Vote to prioritize requests.

Browse Requests

Frequently Asked Questions

How do I fix subtitle timing that is out of sync?

Upload your SRT or VTT subtitle file to the SoftSubs Sync Tool above, enter a positive or negative millisecond offset to shift all timestamps, click Apply Offset to preview the corrected timing, and download the fixed file. A positive offset delays subtitles (they appear later), while a negative offset advances them (they appear earlier). The entire process runs in your browser with no software installation required.

What is subtitle offset?

Subtitle offset is the number of milliseconds by which every timestamp in a subtitle file is shifted forward or backward. A positive offset delays subtitles so they appear later, while a negative offset advances them so they appear earlier. For example, an offset of +2000 delays every subtitle by exactly two seconds, and an offset of -1500 advances every subtitle by one and a half seconds. Most sync problems between different video versions result in offsets that are exact seconds.

Can I sync subtitles for different video versions?

Yes. If your subtitles were timed for a different video release — such as a Blu-ray versus a streaming version, or a theatrical cut versus a director’s cut — you can use the sync tool to apply a constant offset that realigns them. Identify the correct offset by comparing when the first clearly identifiable line of dialogue appears in your video versus when the corresponding subtitle is timed to display. Enter that difference in milliseconds and apply it.

What subtitle formats does the sync tool support?

The SoftSubs Sync Tool supports SRT (SubRip) and VTT (WebVTT) subtitle formats. Upload either format, apply your timing offset, preview the corrected timestamps, and download the fixed file in the same format. If you need to work with ASS or SUB formats, first convert them to SRT or VTT using our free Format Converter, then sync them here.

Is the sync tool free?

Yes, the SoftSubs Subtitle Sync Tool is completely free to use. There are no hidden fees, no account signup, no watermarks, and no usage limits. All processing happens locally in your browser using JavaScript — your subtitle files are never uploaded to any server. Close the tab and no trace of your files remains.

How do I know how many milliseconds to offset?

Play your video and note the exact time when a character begins speaking a clearly identifiable line. Then open your subtitle file and check the timestamp of the corresponding entry. The difference between these two times, converted to milliseconds, is your offset. For example, if the actor speaks at 00:01:05.000 but the subtitle is timed at 00:01:03.000, you need an offset of +2000 milliseconds. If the subtitle appears too late instead of too early, use a negative value.