About this calculator
A time-lapse shoot has three linked numbers: how often you trigger the shutter (interval), how long you shoot for, and how many frames you end up with — knowing any two gives you the third. This calculator also converts your frame count into a final video length at your chosen frame rate, estimates how much storage the shoot will need, and shows the ‘shutter angle’ — the ratio between your shutter speed and interval — which determines whether the played-back motion looks smooth and cinematic or sharp and strobe-like.
How the calculation works
Shot count equals shooting time divided by interval. Knowing any two of the three fixes the third, and when you enter interval and duration the shot count is rounded down. Video length is shot count divided by frame rate (fps), and storage is shot count × file size per shot, divided by 1,024 to get GB.
Shutter angle is your shutter speed divided by the interval. A 100% ratio counts as 360°. Under 30% is flagged as choppy, 30 to 70% as a natural cinematic amount, and over 70% as smooth with heavy motion blur.
Worked examples
- With the defaults, a 5 s interval over 60 minutes gives 720 shots, and at 24 fps the video runs 30 s. At 25 MB per shot, storage is about 17.58 GB.
- A 3-hour sunset at an 8 s interval is 1,350 shots. At 30 fps that is 45 s of video, and about 32.96 GB at 25 MB per shot.
- To make a 10 s video at 24 fps you need 240 frames. Shooting for 30 minutes (1,800 s), set the interval to 7.5 s.
- With a 5 s interval and a 1/50 s shutter, the ratio is only 0.4%, which is choppy. With a 2 s interval and a 1 s shutter, the ratio is 50% (180°), a cinematic amount.
When to use it
It is most useful when you decide the video length first and work backward to the shots, interval and storage you need. It also helps when you want to try different intervals for scenes that change at different speeds, such as clouds and sunsets.
Limits and common mistakes
- The interval has to be longer than the exposure time. If it is shorter than your shutter speed, the camera cannot keep up.
- The camera also needs time to save each photo, so do not set the interval exactly equal to the shutter speed. Leave some margin.
- A scene that goes from day to night changes brightness a lot, so shutter speed changes too. Keep in mind that shutter angle is based on a single shutter speed.
- Storage is an estimate from the file size you enter. It can differ from reality depending on camera and format.
- Also check that your battery and memory card are enough for the whole shooting time.
Guides that pair well with this calculator
Estimates only. Actual file sizes vary by camera, format, and compression settings, and ‘ideal’ motion blur is a matter of creative taste.
Frequently Asked Questions
How do I pick a good interval?+
It depends on how fast your subject moves — clouds and sunsets often work well around 3–10 seconds, while very slow scenes (construction, plant growth) may use minutes between shots. Start with the video duration you want and let this calculator work backward from there.
Why does my video length come out shorter than I expected?+
Video duration depends on both your total shots and your chosen frame rate — the same number of shots plays back faster (and shorter) at 60fps than at 24fps.
What is a 180° shutter angle and why does it matter?+
It’s the traditional film-industry standard where your shutter speed is exactly half your frame interval, producing motion blur that looks natural to viewers. This calculator’s shutter angle result tells you how close your settings are to that look.