Photography Calculators

Timelapse & video

Timelapse Interval Calculator

Clip length is just frames over playback fps, and frames are shoot time over interval. Two hours at 4 s, played at 24 fps, is 1800 frames — 75 seconds. If the histogram on a test shot is wrong, every frame of the clip is wrong. Interval must beat shutter plus write time.

Inputs

Units
h

Wall-clock hours the camera will run.

s

Seconds from one frame start to the next. Clouds: 2–4 s. Shadows on a building: 10–30 s.

fps

24 or 25 for film look, 30 for broadcast, 60 if you want slow-mo headroom.

Results

Frames
1,800

Whole intervals in the shoot, rounded down.

Clip length
75.00s

Frames ÷ playback fps.

Clip length
1.250min

The same clip in minutes, not the shoot time.

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Calculation method

Convert shoot time to seconds (hours × 3600), divide by the interval and round down to whole frames — a partial interval at the end gives no frame. Clip duration is that count divided by the playback frame rate. Minutes are seconds over 60. A 4-second interval for two hours at 24 fps is 1800 frames and 75 seconds of clip.

Exact formula

frames = floor(shootHours×3600 / intervalSeconds). clipSeconds = frames / playbackFps. clipMinutes = clipSeconds/60. Limits: Ramp, deflicker, card-write time and sunset exposure ramps omitted.

People in the frame

At 4 s interval, walking people become dots or ghosts. If you wanted crowds as trails, go 1–2 s. If you wanted empty streets, go longer and wait.

Battery

Dummy battery or a big grip. Intervalometers do not save you from a camera that sleeps after 30 minutes — disable auto power-off.

Frequently asked questions

How much motion blur per still?

A common target is a shutter around half the interval (2 s shutter on a 4 s interval) so the clip looks smooth. That often means ND in daylight. Test a few frames.

Sunset ramps?

This math assumes a fixed interval. Holy Grail sunsets need an exposure ramp; interval can stay, but aperture/ISO/ND will change. Deflicker in post.

Card size?

Multiply frames by your RAW size, then use the SD capacity calculator. Two hours of 45 MB RAWs at 4 s is 1800 frames, about 81 GB — most of a 128 GB card, so start with an empty one or shoot compressed RAW.

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