Timelapse Calculator

Timelapse photography compresses a long real-world event into a short video clip.
The key variables are: how long you shoot, how often you capture a frame, and what frame rate you output.

Core formulas:

Total Frames = Shooting Duration (seconds) / Interval (seconds)
Clip Duration (seconds) = Total Frames / Output Frame Rate (FPS)
Interval = Shooting Duration / (Clip Duration × Output FPS)

Standard output frame rates:

• 24 FPS: Cinematic feel
• 25 FPS: PAL broadcast standard
• 30 FPS: NTSC broadcast / YouTube standard
• 60 FPS: Smooth motion, sports, slow-motion timelapse

Worked example, a sunrise timelapse:

Shooting duration: 90 minutes = 5,400 seconds.
Desired clip length: 30 seconds. Output: 24 FPS.
Total Frames = 5,400 / Interval
Total Frames needed = 30 × 24 = 720 frames
Interval = 5,400 / 720 = 7.5 seconds

If your intervalometer only takes whole seconds, 8 gives 675 frames and a 28-second clip, and 7 gives 771 frames and 32 seconds. Round toward whichever side of 30 you would rather miss on.

Shutter speed (the 180-degree rule):

For natural-looking motion, set the shutter to about half the interval. The rule comes from film cameras, whose rotating shutter was open for half of each frame.
At 8-second intervals that is a 4-second exposure, at 5-second intervals 2.5 seconds.
It is also close to the practical ceiling, because the exposure and the time to write the file both have to fit inside the interval.

Flicker is a separate problem. It comes from auto exposure, and from the aperture closing to a slightly different size each frame. Manual exposure with a locked aperture cures most of it.

Subject-to-interval guide:

Storage estimate:

Storage (GB) ≈ Total Frames × File Size per Frame
RAW files: ~20–50 MB each. JPEG: ~4–10 MB each.
720 RAW frames at 25 MB each ≈ 18 GB, so plan the memory card accordingly.

This page runs forward: you choose the interval and it tells you the clip. If you already know the clip you want and need the interval, the timelapse interval calculator runs the same arithmetic the other way round.