Is the subtitle sync tool free?

Free with no registration, no watermarks, and no file uploads. All processing happens in your browser.

Yes. This standard tool runs entirely client-side. No subtitle data is ever sent to a server.

Does it work on mobile?

Yes. The sync tool is fully responsive and works on iOS, Android, tablets, and desktop browsers.

The first half of my subtitles lines up but drifts further behind over time. How do I fix it?

This is a classic frame-rate stretch or progressive drift problem. Switch to Two-Point Calibration mode, select one correctly aligned cue near the beginning and another near the end, and the tool automatically calculates the stretch ratio and realigns the entire file.

My subtitles are 2 seconds ahead of the audio. Should I use a positive or negative offset?

If subtitles appear before the audio, they are too early. Use a positive delay (shift later) and enter 2000 milliseconds (or 2 seconds) to push all subtitles later by that amount.

Can I batch-sync multiple subtitle files at once?

This page syncs one subtitle file at a time. To batch-sync multiple files, open the Workspace, upload an entire folder, and apply the same offset or two-point calibration to each file.

How do I fix subtitle timing online?

Open this page, drop the subtitle file, choose Time Shift for a constant delay or Two-Point Calibration for drift, then download the corrected SRT or VTT. Everything runs in your browser, so the timing repair happens without uploading the file.

Which timing tool should I use?

Use this page for a fixed offset or two reference points. Use the [frame rate converter](/subtitle-framerate/) when the source and target fps are known, the [speed adjuster](/subtitle-speed/) for playback-rate changes, and [partial subtitle sync](/partial-subtitle-sync/) when only part of the timeline is wrong.

Is this an online SRT adjuster and subtitle resync tool?

Yes. Use Time Shift as a subtitle offset tool for a constant delay, or Two-Point Calibration to resync subtitles that drift over time. The tool works with SRT and other common subtitle formats directly in your browser.

How do I delay subtitles by 15 seconds?

Choose Time Shift, select Later, and enter 15000 milliseconds (or 15 seconds). Every cue moves 15 seconds later, so you can synchronize subtitles online without re-typing the timeline.

Subtitle Sync & Timing Calibration

Fix out-of-sync subtitles effortlessly. Shift timestamps in bulk or use two-point calibration to correct progressive timing drift.

Drag & drop your subtitle file here

Drag and drop subtitle files here or click to browse

SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI, TXT, JSON

Browser-Based Processing · Files Stay on Device

Core Processing Architecture

Key Features

Engineered for video editors and localization teams. Helps enforce common subtitle timing rules and formatting.

Time Shift: move all subtitles forward or backward by a fixed duration

Two-Point Calibration: correct both offset and speed/drift using two reference cues

Automatic linear transformation: t_new = a * t_old + b to align dialogue timing with video playback

Prevents negative timestamps (clamps to 0)

Adjust by hours, minutes, seconds, and milliseconds

Output as SRT or VTT format

Supports SRT, VTT, ASS, SSA, LRC, SBV input formats

Free with no registration or watermarks

Live Preview & Execution Pipeline

Subtitle Sync & Timing Calibration Live Execution Demo

audio_desync.srt

READYDesynced

00:01.200Audio speaks at 00:03.200 (-2000ms delay)

00:05.800Drifting off video speech cue

timecode_aligned.srt

READYSynced

00:03.200Millisecond calibrated

00:07.800Frame-perfect synchronization

In-Memory Processing

File parsing, mutations, and time shifts for standard tools run in browser memory without sending subtitle files to our servers.

Millisecond Precision

Millisecond-accurate timecode parsing and arithmetic prevent synchronization drift across desktop and web players.

Fault-Tolerant Engine

Automatic multi-encoding detection and syntax sanitization gracefully handle malformed cues and unexpected linebreaks.

Production Workflows

Common Use Cases

Real-world scenarios across video post-production, course transcription, and global localization.

SCENARIO #1

Fixed Offset

Subtitles play 2 seconds too early or too late. Use Time Shift to delay or advance all cues by the same amount.

SCENARIO #2

Gradual Drift

Subtitles start in sync but gradually drift apart over time. Two-Point Calibration corrects both the offset and the speed factor.

SCENARIO #3

Frame Rate Mismatch

Subtitles made for 24fps video played on 25fps video. The speed factor correction in Two-Point mode fixes this automatically.

SCENARIO #4

PAL/NTSC Conversion

Subtitle timing is off due to PAL/NTSC conversion. Two-point calibration recalculates timing for the new frame rate.

SCENARIO #5

Opening Credits

Your subtitles start after the opening credits but the video does not. Shift all cues to match the video start.

SCENARIO #6

Multi-Source Sync

Subtitles from one release do not match another release of the same film. Use two-point calibration to realign.

Execution Pipeline

How It Works

Streamlined end-to-end processing pipeline engineered for speed and precision.

STEP 01

Upload & Import

Select your subtitle file that is out of sync.

PHASE 01

STEP 02

Format Analysis

Choose Time Shift for a fixed offset, or Two-Point Calibration for speed/drift correction.

PHASE 02

STEP 03

For Time Shift

enter how much to delay or advance all cues.

PHASE 03

STEP 04

For Two-Point

enter the current and correct timestamps for two reference cues.

PHASE 04

STEP 05

Verify & Export

Click Sync and download the corrected subtitle file.

PHASE 05

Engine Capabilities

Why Choose AllSubConverter?

Client-Side Privacy

Standard tools run in your browser so standard files are not uploaded to our servers.

Fast Local Parsing

Optimized processing engine parses and converts files directly in your browser.

Generous Batches

Up to 50 MB per file, 200 files or 1 GB total per batch.

Universal Compatibility

Runs in modern browsers across Windows, macOS, Linux, iOS, and Android.

Tool Suite

More Subtitle Tools

Subtitle Format Cleaner

Remove formatting, tags and noise

Subtitle Editor

Edit subtitle content and timings

Subtitle Merger

Combine multiple subtitle files

AI Subtitle Translator

Translate to 19 built-in target languages

Batch Subtitle Converter

Convert multiple files at once

Frequently Asked Questions

Subtitle syncing adjusts the timing of subtitle cues so they align correctly with the video audio. This tool supports two modes: a fixed time shift for constant offset, and two-point calibration for correcting speed differences and drift.

You provide two reference points: the current time and the correct time for two cues. The tool calculates a linear transformation (t_new = a * t_old + b) that maps old times to new times, applying the correction uniformly to all cues.

Use HH:MM:SS,mmm format, e.g., 00:01:30,000 for 1 minute 30 seconds. You can also use shorter formats like MM:SS.mmm.

Use Time Shift when all subtitles are off by the same amount throughout the video. Use Two-Point Calibration when subtitles start correctly but gradually drift apart, which indicates a speed/frame-rate mismatch.

Yes. Select the Earlier direction and enter the amount to advance. Times that would become negative are clamped to 0.

Input: SRT, VTT, ASS, SSA, LRC, SBV. Output: SRT or VTT.

Ready to convert your subtitles?