About the Time Lapse Calculator
A time-lapse compresses a long real-world event into a short video by taking photos at a fixed interval and then playing them back at normal video speed. This calculator uses the same arithmetic photographers and cinematographers use to plan any interval shoot: how many photos a given shoot duration and interval will produce, how long the finished clip will run at a chosen frame rate, how much storage it will consume, and how strong the compression effect will be.
The formulas
- Number of shots: total shoot duration (in seconds) divided by the interval between shots (in seconds), rounded down to a whole photo.
Shots = floor(Duration ÷ Interval). - Final video length: the number of shots divided by the playback frame rate.
Video length (seconds) = Shots ÷ Frame rate. - Speed-up factor: how many seconds of real time are packed into each second of finished video, equal to
Interval × Frame rate. - Storage required: the number of shots multiplied by the average file size of one photo.
Choosing an interval
The right interval depends on how fast the subject changes. As a rule of thumb: fast subjects like clouds, sunsets, or crowds usually use a 1 to 5 second interval; moderate subjects like traffic tend to use 2 to 8 seconds; and very slow subjects like construction, plant growth, or star trails commonly use anywhere from 15 seconds to several minutes. Too long an interval makes motion look jerky; too short an interval wastes shots, storage, and battery without adding visible smoothness.
Common uses
- Sunrise, sunset, and cloud movement sequences
- Construction progress and long-term building projects
- Plant growth and other slow biological processes
- Night sky and star trail photography
- Crowds, traffic, and city motion
Precision note
This calculator assumes every shot fires exactly on schedule and that no frames are dropped. In practice, slow memory cards, long exposures near the interval length, or a camera buffer that has not cleared can cause a shot to be skipped, which slightly shortens the real shot count and video length below what is calculated here. Test a short run before committing to a multi-hour shoot.