Frame rate converter
Footage shot at one frame rate often has to be delivered at another — film at 24 fps for an NTSC broadcast at 29.97, or a PAL clip at 25 fps for an online target. This converter compares two frame rates, shows the rate ratio, and recalculates a frame count so a clip keeps the same real-time duration at the new rate.
How it works
Given a source and target frame rate, the tool computes the ratio (target ÷ source). To re-express a frame count at the new rate while preserving duration, it first finds the clip’s length in seconds — frames ÷ source fps — then multiplies by the target fps:
new frames = (frames ÷ source fps) × target fps
It also surfaces the NTSC quirk: 23.976 vs 24, and 29.97 vs 30, differ by exactly the 1000/1001 pulldown factor, which is why those rates look almost — but not quite — like whole numbers.
Example
A clip of 240 frames at 24 fps lasts 240 ÷ 24 = 10 seconds. Converting to 30 fps for the same duration: 10 × 30 = 300 frames. The rate ratio is 30 ÷ 24 = 1.25.
Common frame rate conversions
| Source fps | Target fps | Rate ratio | Frame count change |
|---|---|---|---|
| 24 | 23.976 | ~0.999 (1000/1001) | Slightly fewer frames |
| 24 | 30 | 1.25 | 25% more frames |
| 25 (PAL) | 29.97 (NTSC) | ~1.199 | About 20% more frames |
| 29.97 | 25 | ~0.834 | About 16.7% fewer frames |
| 30 | 29.97 | ~0.999 (1000/1001) | Slightly fewer frames |
| 60 | 24 | 0.4 | 60% fewer frames |
The 1000/1001 pulldown factor
The 23.976 and 29.97 frame rates are not round numbers by accident — they exist because of the NTSC colour television standard adopted in 1953. When colour was added to the existing monochrome NTSC signal, engineers needed to prevent interference between the colour subcarrier and the existing audio carrier. The solution was to slow the frame rate from exactly 30 fps to 30 × 1000/1001 ≈ 29.97 fps (and correspondingly from 24 to 23.976).
The consequence is that video shot at 29.97 fps runs very slightly slower than video at 30 fps — by about 0.1%. Over an hour, 29.97 fps video is about 3.6 seconds shorter in real time than 30 fps video with the same frame count. This matters for timecode accuracy: drop-frame timecode (29.97 DF) compensates by periodically skipping frame numbers (not actual frames) to keep the timecode synchronized with real elapsed time; non-drop-frame timecode (NDF) simply counts frames without correction and drifts from wall-clock time.
When frame-rate conversion changes playback speed
Re-expressing a frame count for the new rate (as this tool does) preserves real-time duration — the clip plays at the same speed in seconds. But some workflows instead keep the frame count constant and change the rate, which changes the playback speed:
- 24 fps footage played at 25 fps — common in European post-production where PAL broadcast requires 25 fps. The clip plays back 4.17% faster, slightly raising pitch and shortening the duration. Audio is usually pitch-corrected separately.
- Overcranked footage (e.g., 120 fps) delivered at 24 fps — the frame count is kept the same, so 5 seconds of real action becomes approximately 25 seconds of slow motion at 24 fps. This is intentional slow-motion, not a conversion error.
This tool models the duration-preserving conversion (same real-time length, different frame count). For speed-change scenarios, the ratio tells you the playback speed multiplier directly: a ratio of 1.25 means the clip plays 25% faster in real time.
Enter your rates and the answer updates instantly — all in your browser, nothing uploaded.