How to Plan a Time-Lapse: Interval & Frames

Updated October 2026

Work out the intervalometer setting from how long the event lasts and how long the clip should run, then check the exposure fits inside the interval and the card holds every frame.

9 min readBeginner

Interval
Frame count
Speed-up
Storage

On this page

The three numbers

Every time-lapse is the same trade: a long stretch of real time squeezed into a short clip. Decide how long the event lasts, how long the finished shot should run and the timeline frame rate, and the rest follows.

Frames, interval and speed-up

Frames   = Clip length (s) × Frame rate
Interval = Event duration (s) ÷ Frames
Speed-up = Event duration ÷ Clip length

Where

Event duration: How long you will shoot, in real time(s)
Clip length: How long the shot runs in the edit(s)
Frame rate: The timeline rate the frames will play at(fps)

Example: A two-hour sunset into a 10-second shot at 24 fps

Calculation:: Frames = 10 × 24 = 240; Interval = 7,200 ÷ 240 = 30 s; Speed-up = 7,200 ÷ 10
Result:: Shoot every 30 seconds, 240 frames, 720× faster than real time

These are the formulas CineMath's Time Lapse calculator uses: enter the real duration in minutes, the playback length in seconds and the frame rate, and it returns the interval first, because that is what you set on the camera. The free time-lapse calculator does the same in your browser.

Worked examples

Interval for common shots, 24 fps unless noted

Shot	Event	Clip	Frames	Interval	Speed-up
Clouds	30 min	15 s	360	5 s	120×
City traffic	1 h	10 s	240	15 s	360×
City traffic, 25 fps	1 h	10 s	250	14.4 s	360×
Sunset	2 h	10 s	240	30 s	720×
Stars	4 h	20 s	480	30 s	720×
Event setup	8 h	30 s	720	40 s	960×

The speed-up depends only on the event and the clip; the frame rate decides how many frames you need to fill the clip, and so how often you shoot.

Working it the other way

On location the question is often reversed: you have an interval that suits the subject and need to know how long to stay, or you have a fixed window and need to know what clip it will make.

Shooting time from frames and interval

Event duration = Frames × Interval

Example: 360 frames at a 5-second interval

Calculation:: 360 × 5 = 1,800 s
Result:: 30 minutes on location for a 15-second clip at 24 fps

Clip length from what you shot

Clip length (s) = Event duration ÷ Interval ÷ Frame rate

Example: Two hours at a 10-second interval, played at 24 fps

Calculation:: 7,200 ÷ 10 ÷ 24 = 30
Result:: A 30-second clip (720 frames)

Choosing an interval

The interval sets how fast motion looks. Short intervals keep fast subjects smooth; long ones compress slow change enough to see it. These are common starting points, not rules; the formula then tells you how long to shoot for the clip you want.

Starting points

Subject	Typical interval
Fast clouds, crowds, traffic	1–3 s
Slow clouds, sunsets, shadows	5–10 s
Night sky, stars	20–30 s (set by the exposure)
Plants, tides, all-day light	1–5 min
Construction	5–15 min, or more

Exposure and the interval

Each exposure, plus the time the camera needs to write the frame, has to fit inside the interval. A 25-second star exposure cannot run at a 20-second interval. CineMath's calculator warns when the interval falls below one second, because the camera then has to save each frame faster than that.

The longest exposure an interval allows

Exposure < Interval − camera write time

Write time varies with the camera, the file format and the card; time a few frames on your own setup.

Exposure time also sets motion blur. Borrowing the cinema idea of a 180° shutter, an exposure of half the interval gives motion a continuous, streaky look; a short exposure gives a crisper, more staccato one. At a 5-second interval, half the interval is a 2.5-second exposure, which in daylight usually needs a strong ND filter. The slow-motion guide covers shutter angle in moving footage.

23.976, 25 and 30 fps

Use the frame rate of the timeline the shot will live in. At 23.976 fps a 10-second clip needs 239.76 frames, so shoot 240; the interval for a two-hour event is 7,200 ÷ 239.76 = 30.03 s, which rounds to the same 30 seconds. At 25 fps the same clip needs 250 frames and a 14.4-second interval for a one-hour event.

Stills shot for a time-lapse have no frame rate of their own. Import them as an image sequence at the timeline rate, and the clip length is simply frames ÷ frame rate.

Storage per shoot

Card space for a sequence

Storage = Frames × Average file size
Frames per card = Card size ÷ Average file size

File size varies with the camera, the format (raw or JPEG), compression settings and the scene itself. Shoot a test frame of your actual scene and read its size.

Example: Raw frames averaging 50 MB (an assumed figure; measure your own)

Calculation:: 240 frames × 50 MB = 12,000 MB; 128 GB ÷ 50 MB = 2,560 frames
Result:: 12 GB for the sunset; a 128 GB card holds about 2,560 frames

Long sequences add up quickly: the 4-hour star shoot above is 480 frames, 24 GB at the same assumed size. CineMath's Time Lapse calculator flags any plan over 10,000 frames as a long shoot; check the card and the battery or mains power will last it.

Long-term time-lapses

Case study

A six-month build in one minute

Scenario

A construction client wants a one-minute 24 fps film of a build, shooting 8 working hours a day for 180 days.

Challenge

Pick an interval that fills the minute from daylight working hours only, and size the storage.

Solution

Count only the hours you will shoot: 8 hours a day for 180 days.
Frames for the clip: 60 s × 24 fps.
Divide the shooting time by the frames.

The numbers

Shooting time: 8 × 180 = 1,440 h = 5,184,000 s
Frames: 60 × 24 = 1,440
Interval: 5,184,000 ÷ 1,440 = 3,600 s, one frame an hour
Speed-up: 5,184,000 ÷ 60 = 86,400×

Result

One frame an hour gives exactly one minute. Shooting every 15 minutes gives 5,760 frames: room to cut the dull weeks and keep the busy ones.

Key takeaways

Shoot more often than the minimum and choose frames in the edit.
At 5,760 frames and an assumed 50 MB each, that is 288 GB: plan for remote offload or a large card.

For time-lapses where the camera moves, or that run from daylight into night, see hyperlapse and day-to-night.

Next step: open the Time Lapse calculator in CineMath, or the free time-lapse calculator in your browser, set the event length, clip length and frame rate, and read off the interval to dial into the intervalometer.