Video frame rate conversion calculator

Enter the source rate, target rate, and source frame count to see whether a duration-preserving conversion needs duplicated or dropped frames, the nearest whole target frame count, and the exact duration obtained by keeping every original frame instead. It is useful for planning conform, retiming, animation, archival, and delivery workflows before opening an editor or transcoder.

Choose between matching duration and preserving frames

Frame rate conversion can describe two different operations, and confusing them is a common source of timing mistakes. A duration-preserving conversion keeps the running time close to the source. To do that, the calculator multiplies the source frame count by the target-to-source rate ratio. Moving to a higher rate requires more displayed frames, so frames must be duplicated or synthesized; moving to a lower rate requires fewer displayed frames, so frames must be dropped or blended. Because an actual video cannot contain a fraction of a frame, the ideal count is rounded to the nearest whole frame and both values are reported. The alternative is a frame-preserving conform. In that case, no frame is created or removed: every source frame is simply played at the target rate. The running time therefore changes. This distinction matters because a 24 fps clip converted for 30 fps delivery is not the same operation as the same 240 frames interpreted as 30 fps footage. The first aims to retain ten seconds; the second lasts eight seconds.

Read the frame counts and timing results

Start with the action field. It says duplicate when the target rate is higher, drop when it is lower, and none when both rates match. The conversion ratio is target frame rate divided by source frame rate. The ideal target frame count applies that ratio to the source count and represents the mathematical amount needed to preserve duration exactly. The target frame count is its nearest usable whole-frame value. Frames to duplicate and frames to drop compare that rounded result with the original count, so only one will be greater than zero. For timing, source duration is the source frame count divided by the source rate. Preserved frame count duration divides that same count by the target rate instead. Duration change subtracts the original duration from the frame-preserved duration: a negative result means the clip becomes shorter, while a positive result means it becomes longer. Reported timing values are rounded to nine decimal places for stable output, while the calculation itself uses the full numeric inputs.

Apply the calculation in real production workflows

Use the result as a planning calculation rather than as a claim about a particular interpolation algorithm. The tool tells you how many frame positions the rate relationship requires, but it does not choose whether an application should repeat frames, blend neighboring images, estimate optical flow, or change playback speed. Those choices affect motion quality, cadence, audio handling, and render cost. For editorial delivery, compare the rounded duration-preserving target count with the expected timeline length before transcoding. For animation, the duplicate count can help estimate how often held drawings or rendered frames will repeat at the delivery rate. For archival or restoration work, the frame-preserved duration exposes the exact speed change introduced by interpreting historical footage at a modern rate. Decimal rates such as 23.976 and 29.97 are accepted, as are exact integer rates. Both rates must be positive finite numbers, and the source frame count must be a positive safe integer. The API charges $0.002 per calculation, while the browser calculation uses the same deterministic core logic.