Subtitle Shifter — SRT Timing Studio
Fix out-of-sync subtitles in seconds. Shift every timestamp by milliseconds, repair progressive drift with two-point resync, convert between 23.976 / 24 / 25 fps, fix overlaps and validate your SRT — all in one free online tool. 100% client-side: your subtitle files never leave your browser.
The studio
.srt file here, or click to browseWhich fix do you need? (subtitle sync problem guide)
| Symptom | Cause | Fix in this tool |
|---|---|---|
| Every subtitle is late (or early) by the same amount | Constant delay baked into the rip or video | Shift timing — enter the offset in ms |
| Starts in sync, gets worse toward the end | Framerate mismatch (e.g. 23.976 fps subs on 25 fps video) | Drift resync (two points) or FPS convert |
| Subtitles flash by too fast / overlap each other | Bad rip or merged cues | Fix overlaps in the Fix & validate tab |
| Player shows "invalid subtitle" or skips lines | Malformed SRT (bad timecodes, bad numbering) | Validate, then download the cleaned file |
Subtitle sync tool: common scenarios
Shift a subtitle file that's out of sync
The most common case: an SRT file out of sync by a fixed amount — subtitles always a couple of seconds late, or an SRT file not synchronized with your particular video encode. When people ask how to fix subtitle sync, this is usually what they mean. Load the file, measure the delay once, and shift the subtitle file by that offset: positive values delay subtitles, negative values pull them earlier. To shift subtitle time by a fixed amount without re-downloading anything, correct the SRT here — only timestamps change — then use the fixed file everywhere. To shift a subtitle file and sync a subtitle file for good, export once: every download is a clean, sequentially numbered SRT, so numbering-related "SRT file sync" problems disappear too.
Flat offset vs. drift: picking the right subtitle offset tool
A subtitle offset tool exists to offset a subtitle file by one constant correction, which is exactly right when the delay never changes — for example after you adjust subtitle delay for a video with a long intro. It is the wrong fix when subtitles start fine and get progressively worse: that needs drift resync, not a bigger offset. Rule of thumb: if shifting fixes the beginning but the end is still off, stop offsetting and resync the drift instead. (Dealing with subtitles that are simply late by a constant amount — the classic "subtitle late shift" case? The Shift tab handles it in one step.) As an online subtitle offset tool, every subtitle offset fix here runs in your browser — nothing to install.
Free online subtitle sync — no install
This page is a free subtitle sync online tool — a subtitle shifter online that runs entirely in your browser — and a subtitle sync tool that works online with no install and no account. Unlike a subtitle sync program you must install, there is nothing to download. If you were looking for a subtitle shifter tool, a subtitle time shifter online, an SRT subtitle shifter (also called a subtitle SRT shifter, sometimes shortened to "sub shifter"), a subtitle sync fixer, or a subtitle sync shifter, this is it: shift subtitles online, re-sync drift, convert FPS, and validate, in one place. For hands-off correction, two-point drift resync is the closest thing to automatic subtitle sync: give it two correct reference times and it computes the linear correction for every cue.
Subtitle sync for MPC-HC, Stremio, Prime Video and other players
Desktop players have built-in delay keys (see the quick guide below), but apps like Stremio and Prime Video offer little or no subtitle sync control of their own. Whether you need subtitle sync for MPC-HC, Stremio, or Prime Video, the reliable fix is to correct the file itself: shift or resync the SRT here once, and it plays in sync on MPC-HC, Stremio, Prime Video, Plex and smart TVs alike — no per-device tweaking.
Coming from Subtitle Edit
If you normally fix timing with Subtitle Edit's shift feature (Synchronization → "Adjust all times" — the subtitle edit shift workflow), this tool covers the same Subtitle Edit shift time case with no install, and adds the two-point drift workflow for the case tutorials describe as "how to sync subtitles in Subtitle Edit when the offset grows over time": pick one correct subtitle near the start and one near the end, and the linear map does the rest.
Re-syncing a file you already shifted
Need to re-sync subtitles after an earlier fix attempt? Load the already-shifted file and apply the new correction on top — or reload the original and start clean. Every operation shows a before/after preview, so you can verify each subtitle re-sync before downloading.
Quick sync while watching (VLC, mpv, MPC-HC)
These player shortcuts fix sync temporarily for the current session. For a permanent fix that works everywhere (including Stremio and Prime Video, which lack fine controls), correct the file with the studio above.
- VLC: press
J/Kto nudge subtitle delay, or Tools → Track Synchronization. - mpv: press
z/Z, or launch with--sub-delay=1.5. - MPC-HC: press
+/-on the numpad. - Subtitle Edit (desktop): Synchronization → "Adjust all times" for a flat shift.
FPS conversion reference
| From → To | Exact ratio | Typical use case |
|---|---|---|
| 23.976 → 25 | 24000/1001 ÷ 25 ≈ 0.95904 | NTSC Blu-ray subtitles on a PAL encode — the most common mismatch |
| 25 → 23.976 | 25 ÷ 24000/1001 ≈ 1.04271 | The reverse |
| 29.97 → 25 | 30000/1001 ÷ 25 ≈ 1.19880 | Broadcast rips |
| 24 → 25 | 0.96 | Cinema → PAL speedup |
| 25 → 24 | ≈ 1.04167 | PAL → cinema |
How this compares
| Tool | Flat shift | Drift resync | FPS convert | Overlap fix + validator | Install needed |
|---|---|---|---|---|---|
| This tool (nrtechstudio.com) | ✅ ms-precision | ✅ two-point linear | ✅ exact rational math | ✅ | No — browser |
| resyncsrt.com | ✅ | ❌ | ❌ | ❌ | No |
| subtitlekit.com | ✅ | ❌ | ❌ | ❌ | No |
| devtoollab.com | ✅ | ❌ | ❌ | ❌ | No |
| Subtitle Edit | ✅ | ✅ (manual) | ✅ (via timecodes) | ✅ | Yes — desktop app |
Feature comparison checked October 2026. Subtitle Edit remains the most powerful desktop option; this tool is the no-install web alternative with drift resync built in.
Frequently asked questions
How do I fix subtitles that are out of sync?
First find out what kind of sync problem you have. If every subtitle is off by the same amount (e.g. always 2 seconds late), use a flat shift: enter -2000 ms in the Shift tab. If subtitles start fine but drift further out of sync as the video plays, use two-point drift resync. If the subtitles were timed for a different framerate, use FPS convert.
Why do my subtitles get progressively more out of sync?
Progressive drift almost always means a framerate mismatch: the subtitle file was timed against a video encoded at one framerate (for example 23.976 fps) while your copy runs at another (for example 25 fps). The timing error grows linearly over the runtime.
How do I shift subtitles forward or backward by a few seconds?
Paste or drop your SRT file, open the Shift tab, and enter the offset in milliseconds — positive values delay subtitles (use when they appear too early), negative values move them earlier (use when they appear late). 2500 ms = 2.5 seconds.
How do I convert subtitles from 23.976 fps to 25 fps?
Open the FPS Convert tab, set "from" to 23.976 and "to" to 25. Every timestamp is multiplied by the exact ratio 23.976/25 using rational arithmetic, so there is no accumulated rounding drift.
What is subtitle drift resync (two-point sync)?
You give two reference points: the correct time of one subtitle near the beginning and one near the end. The tool computes the linear map through those points and applies it to every cue — fixing constant offsets and progressive drift in one operation.
How do I fix overlapping subtitles in an SRT file?
Open the Fix & Validate tab and click "Fix overlaps". The tool sorts cues by start time and clamps any cue that runs into the next one, with an optional minimum gap (default 40 ms).
Why are my subtitles always late (or always early)?
A constant offset usually comes from a delay baked into the video file or the rip. Measure it once — pause at a clear line of dialogue, note the difference — then apply that offset with the opposite sign in the Shift tab.
Can I sync subtitles without downloading a new file?
Yes. Timing fixes only rewrite timestamps — the text stays identical. Load your existing SRT, apply the fix, and download the corrected file.
How do I check if my SRT file is malformed?
Load the file and open the Fix & Validate tab. The validator reports malformed timecode lines, end-times before start-times, non-sequential numbering, empty cues, overlaps and out-of-order cues. Export renumbers everything sequentially.
Does shifting subtitles reduce quality?
No. Only timestamps are rewritten; subtitle text, styling and order are untouched. The operation is lossless and reversible.
How is this different from Subtitle Edit's shift feature?
Subtitle Edit is a desktop editor you must install. This tool runs entirely in your browser with no install, and adds two-point drift resync and one-click FPS conversion plus an SRT validator and overlap fixer in one page.
Are my subtitle files uploaded to a server?
No. Everything runs locally in your browser — the file is parsed, transformed and re-downloaded on your own device. Nothing is sent anywhere.
How do I sync subtitles in VLC, mpv or MPC-HC?
In VLC press J/K, in mpv press z/Z, in MPC-HC press + / - for a temporary fix. For a permanent fix that works everywhere including Stremio and Prime Video, correct the SRT file with the Shift tab above.
My SRT numbers jump (1, 2, 5, 6). Is that a problem?
Most players tolerate it, but some strict parsers don't. Every export from this tool renumbers cues sequentially starting at 1.
What framerate should I pick for FPS convert?
Pick the framerate the subtitles were timed for as "from", and your video's framerate as "to". The most common pair is 23.976 → 25. If unsure, try that first.