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Time-Lapse Calculator

Computes the number of frames, the shooting interval and the playback speed-up factor for a time-lapse from the real event duration, the desired clip length and the frame rate, plus storage needs from a per-frame file size.

When to use

You are planning a time-lapse and need the intervalometer setting, how many shots it takes, or how much card space is required.

Do not use when: You need the file size of a normal video (use video-file-size) or the size of individual photos (use image-file-size).

Formula

frames = clip_duration_seconds × fps; interval_seconds = event_duration_minutes × 60 / frames; speed_factor = event_duration_minutes × 60 / clip_duration_seconds; storage_gb = frames × file_size_per_frame_mb / 1000

The interval must be longer than the exposure time plus the camera's write time; intervals below about 1 s exceed what most intervalometers allow. Frame count is rounded to a whole number before the interval is derived.

Inputs

Parameter	Type	Unit	Required	Description
`event_duration_minutes`	number	min	yes	Real-time length of the event to record, in minutes. Range: > 0, ≤ 1000000
`clip_duration_seconds`	number	s	yes	Desired length of the finished time-lapse clip, in seconds. Range: > 0, ≤ 86400
`fps`	number	fps	default 30	Frames per second of the final video (24, 25, 30, 60). Range: ≥ 1, ≤ 240
`file_size_per_frame_mb`	number	MB	no	Optional size of one captured frame in MB (RAW 25–50, JPEG 5–12); returns the total storage needed. Range: > 0, ≤ 1000

Outputs

Output	Type	Unit	Description
`frames`	integer		clip_duration_seconds × fps, rounded.
`interval_seconds`	number	s	event duration / frames: the intervalometer setting.
`speed_factor`	number	×	Event duration / clip duration: how many times faster than real time the clip plays.
`shooting_time_text`	string		The event duration written as hours and minutes.
`storage_mb`	number	MB	frames × file_size_per_frame_mb (only when the file size is given).
`storage_gb`	number	GB	Storage in decimal gigabytes (only when the file size is given).

Example

2-hour event as a 30 s clip at 30 fps, 25 MB RAW frames: {"event_duration_minutes":120,"clip_duration_seconds":30,"fps":30,"file_size_per_frame_mb":25} → {"frames":900,"interval_seconds":8,"speed_factor":240,"storage_gb":22.5,"shooting_time_text":"2 h 0 min"}

6-hour sunset as a 20 s clip at 24 fps: {"event_duration_minutes":360,"clip_duration_seconds":20,"fps":24} → {"frames":480,"interval_seconds":45,"speed_factor":1080}

GET https://tttkmbb.com/api/v1/calculate/time-lapse?event_duration_minutes=120&clip_duration_seconds=30&fps=30&file_size_per_frame_mb=25

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/time-lapse (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/time-lapse · Markdown: https://tttkmbb.com/photography/time-lapse.md · JSON definition: https://tttkmbb.com/photography/time-lapse.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="time-lapse"
OpenAPI operationId: calculate_time_lapse
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Wikipedia – Time-lapse photography (reference)
Wikipedia – Intervalometer (reference)

FAQ

What interval should I use for clouds, sunsets or stars?

Rules of thumb: fast clouds 1–3 s, sunsets 5–10 s, slow clouds and shadows 10–30 s, stars 20–40 s (limited by the exposure), plants and construction minutes. Compute the interval from the planned clip length and check it against these.

Does the shutter speed matter?

The exposure time must fit inside the interval with margin for the camera to save the file; for smooth motion many shooters use a shutter of about half the interval ('dragging' the shutter).

Related calculators

Image File Size Calculator — Per-frame file size from resolution and format.
Video File Size Calculator — Size of the rendered clip from its bitrate.
Data Storage Converter — Convert the storage figure between units.