Measure the same line twice
Pause at a short, distinctive spoken line and note its starting time. Find the matching subtitle and note when it appears. Convert minutes to seconds first: 2 minutes 15 seconds is 135 seconds. Milliseconds are one thousandth of a second.
How the calculation works
Spoken timestamp minus subtitle timestamp gives the shift in seconds. Multiplying by 1,000 gives milliseconds. If speech starts at 10 seconds and text at 11 seconds, the text is one second late: use −1,000 ms. If text arrives at 9.5 seconds, use +500 ms to move it later.
One offset cannot repair every track
Check another line later in the film. A steady mismatch may respond to a single offset. If timing drifts or changes after an inserted scene, look for subtitles matching that specific cut or episode. This calculator does not change a video, download subtitles or translate dialogue.
Keep a comfortable reading pace
Test the result over several exchanges, not only a single fast word. Some captions intentionally appear slightly before speech to allow reading. Keep the smallest adjustment that improves the whole conversation.