Enter a frame count and source and target frame rates. The tool shows what happens if the same frames play at a different rate, then separately shows a duration-preserving conversion. These are different editing operations with different motion and audio consequences.
How the calculation works
Source duration = source frames ÷ source fps. Reinterpreted duration = source frames ÷ target fps; playback speed = target fps ÷ source fps. A duration-preserving conversion instead estimates source duration × target fps output frames. Fractions such as 30000/1001 preserve more precision than typing 29.97.
Worked example
2,400 frames at 24 fps last 100 seconds. Playing those same frames at 25 fps lasts 96 seconds and runs 4.167% faster. Preserving 100 seconds at 25 fps instead needs approximately 2,500 output frames, which may require duplicated, blended or synthesized frames depending on the software.
Before using the result
This calculator uses constant-rate frame counts. It does not calculate drop-frame timecode labels, variable-rate timestamp duration, optical-flow quality or audio resampling. Fractional output frame counts must be rounded to a deliverable frame boundary. Verify sound synchronization after any interpretation or conversion change.
Keep the source values with your project notes. A number calculated from an assumed bitrate or representative sample is only as useful as that assumption. Check a real file or measured export when a deadline, upload cap or storage purchase depends on the answer.
