✳ FREE CALCULATOR
Speed and duration calculator
Find the duration a clip becomes after a speed change, and the speed factor needed to hit a target duration.
- Duration at 1.5×
- 1m 0s
- Speed needed to reach 1m 0s
- 1.50×
- Time removed
- 30s
- Audio note
- within normal pitch-correction range
ffmpeg's atempo filter handles 0.5×–2.0× per pass; larger changes need chained passes and sound increasingly artificial.
Calculated as: new duration = duration ÷ speed; needed speed = duration ÷ target duration
What this assumes
- Speeding up video drops or blends frames; the result is smooth only if the source frame rate is high enough.
- Audio pitch correction degrades noticeably outside roughly 0.5×–2×.
Koldflux works these numbers out for you when it exports - the calculators exist because our own pipeline needed them first.
Automate this in Koldflux