Frame Rate Converter
What happens to duration and motion when 25p material has to land on a 23.976 timeline. The calculator above takes source fps, target fps and duration and returns new duration, speed factor, pitch shift and method recommendation — computed in your browser, with no sign-up and nothing leaving your device.
Frame Rate Converter
- New duration
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- Speed factor
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- Pitch shift
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Runs entirely in your browser — no sign-up, nothing transmitted.
What the number actually depends on
25p slowed to 24p runs 4.1 % longer and drops audio pitch by about 0.7 semitones without correction.
50p to 25p is the only clean halving in the PAL world — every other conversion interpolates or drops frames.
The gap between a number that goes into a quote and one that holds on the day is rarely the formula — it is whether the constraints were entered honestly. That is why the inputs are spelled out below.
Common mistakes
These come up most often in practice. They rarely break the maths; they routinely break the day:
- Conforming without pitch correction on dialogue
- Shooting 25p for a US delivery that needs 23.976
In day-to-day production
23.976 is exactly 24 × 1000/1001, a legacy of NTSC colour that still shapes delivery specs.
The number belongs in post and review — the point where a decision is still free to change. Working it out on the shoot day is no longer calculating; it is finding out.
In TillyGen this is not a separate step: the result sits inside the plan itself, alongside the shot list, schedule and call sheet. Change a constraint and the dependent values move with it — the affected parts of the plan are flagged rather than quietly left behind.
Frequently asked
How accurate is the Frame Rate Converter?
The maths is exact; the inputs rarely are. Treat the result as a solid floor and add your buffer deliberately rather than smuggling it into the inputs — a flattered input hides the buffer from everyone who plans with it later.
Is the calculator free?
No. It runs entirely in your browser, with no sign-up and nothing transmitted. There is no usage limit and no account.
Where does this fit in production planning?
In post and review. There it is a basis for deciding; later it is only a finding.
Can I export the result?
The calculator itself only displays the value. In TillyGen it lands directly in the shot list, schedule and call sheet, and goes out as PDF, CSV or through the API to everyone working from it.
What does the calculator return?
New duration, speed factor, pitch shift and method recommendation. The first value is the one you carry into the plan; the rest show how sensitively it reacts to the inputs.
What should I watch for in the result?
Mainly this: conforming without pitch correction on dialogue. That is the mistake that most often turns a correctly calculated number into one that does not hold.