Is 23.976 the same as 24 FPS?

No. The difference is small but accumulates over a long runtime.

Can I infer FPS from an SRT file?

Not reliably. SRT stores timestamps rather than a frame-rate declaration.

Should I also add an offset?

Sometimes. Apply the FPS correction first, then add a constant offset if the corrected file is uniformly early or late.

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sync7 minUpdated Aug 17, 2026

Prepared by SubtitleBot · technical examples verified with the built-in tools

Subtitle Frame Rate Conversion: 23.976, 24 and 25 FPS

Understand subtitle drift caused by frame-rate conversion and calculate corrected timestamps safely.

Why frame rate affects subtitle timing

Subtitle files store time, not frames, but releases converted between cinema and broadcast speeds often have different runtimes. A subtitle timed against one version gradually moves away from dialogue in another.

Use the correct ratio

Rescale every start and end timestamp with the same ratio. Do not round each intermediate calculation to whole seconds; retain millisecond precision until export.

Formula

corrected time = original time × source FPS ÷ target FPS
24 → 25 = × 0.96
25 → 24 = × 1.0416667

Common conversions

23.976 and 24 are close but can still create visible drift in a long film. The difference between 24 and 25 is about four percent and becomes obvious quickly.

23.976 → 25: × 0.95904
25 → 23.976: × 1.042709
24 → 25: × 0.96
25 → 24: × 1.041667

Validate after conversion

Check a cue near the beginning, middle, and end. If all three align, the conversion is likely correct. If only one section aligns, the video may be a different cut.

Frequently asked questions

Is 23.976 the same as 24 FPS?: No. The difference is small but accumulates over a long runtime.
Can I infer FPS from an SRT file?: Not reliably. SRT stores timestamps rather than a frame-rate declaration.
Should I also add an offset?: Sometimes. Apply the FPS correction first, then add a constant offset if the corrected file is uniformly early or late.