What to set once the filter is on — including two filters stacked, where the stops add and the numbers on the rings do not. Free, no sign-up, nothing stored.
Timelapse calculator
Timelapse calculator: how long your clip will be, how many frames it takes and how much card space it eats, before you spend the evening finding out.
Give it a session length, an interval and a playback rate, and it returns the clip you will actually get — its length, the frame count, the card space, the batteries, and how many times faster than life it will run. It also answers backwards: name the clip you want and it gives you the interval. Free, no account, nothing stored.
What it does, and why it is here
An hour beside a tripod, firing every five seconds, produces thirty seconds of video. Not three minutes. Thirty seconds — 720 frames at 24 fps.
That arithmetic is trivial and almost nobody does it before the shoot. The result is the two standard disappointments: an evening spent for four seconds of footage, or a card that fills at nine o’clock in the middle of the sunset you came for. Both are decided by numbers you can know in advance, and neither is visible on the back of the camera while it is happening.
So this page exists to be used before the tripod comes out. It turns the plan into every figure the evening will need — frames, clip, gigabytes, batteries, shutter actuations — and it will invert the question when you are working the other way round, which is most of the time: you know the clip you want, not the interval that yields it.
What you fill in
- Session length, in minutes — how long you will actually be shooting.
- Interval between frames, in seconds — set by the subject, not by the clip you want. The field carries the usual ranges, and the table further down has the rest.
- Playback rate, in fps — 24 for a cinematic feel, 25 or 30 to match the footage around it, 60 for slow motion later.
- Size of one frame, in MB, optional — about 25 for a 24 Mpx raw, about 8 for a JPEG. Fill it in and the answer sizes the card.
- Frames per battery, optional — turns the plan into a packing list.
- Card capacity, in GB, optional — with the frame size, it answers the question that ends sessions early: the longest session this card holds at this interval.
- Clip wanted, in seconds, optional — the question reversed. Name the clip length and the tool names the interval that delivers it over this session.
- A city and a day, optional — and this is the part worth knowing about. Give them and the tool works out the evening window for that place: golden hour to the end of civil twilight, in minutes, which you can then use as the shooting time in one click.
What you get back
- Finished clip — the length in seconds, which is the number the whole plan lives or dies by.
- Frames to shoot, time spent shooting, and how many times faster than life the result runs.
- Card space needed and batteries, from the two optional figures.
- Shutter actuations, given as a percentage of a shutter rated for 400,000 and one rated for 150,000. Timelapse is the one discipline that genuinely wears a mechanical shutter out, and a season of it is worth counting.
- The same frames at every common playback rate, yours in bold — because the clip you have is often two seconds short of what an edit needs, and changing the rate is free where reshooting is not.
- The other way round — the interval for the clip length you asked for, and the longest session your card holds at the interval you chose.
- The evening, when you named a place and a day — the window from golden hour to the end of civil twilight, and the holy grail figure that goes with it: roughly how many stops of light will drain out of that window, and how often you will have to give one back on ISO or shutter to keep the exposure smooth.
What it does not do
It plans the shoot; it does not process it. Deflickering, ramping the exposure and assembling the frames into a video all happen afterwards, in software of your choosing.
It cannot choose the interval for you either, because that depends on how fast your subject moves and on nothing the tool can see. And the evening window is astronomy, not weather: it says when the light will change, not whether there will be a cloud in front of it.
Choosing the interval by subject
The one input the calculator cannot derive. Set it by the subject and let the clip length fall where it falls; set it by the clip length and you get either a jerky sequence or a wasted card.
| Subject | Interval that usually works |
|---|---|
| People, traffic, a busy street | 1–2 s |
| Fast clouds, a sunset, a tide | 2–5 s |
| Slow clouds, shadows across a valley | 5–15 s |
| Stars, the Moon crossing the sky | 20–30 s |
| Construction, plants growing, decay | minutes to hours |
Too long an interval strobes: a car appears in three consecutive frames at three completely different places, and the eye reads a stutter rather than motion. Too short an interval gives a clip in which nothing appears to happen, and a card full of near-identical files — at one-second intervals a raw sequence eats roughly a gigabyte and a half per minute of shooting.
Questions
Is this calculator free?
Yes. No account, no e-mail, nothing stored — the plan you type is used to answer and then forgotten.
How many frames do I need for a usable clip?
Work back from the clip: five seconds at 24 fps is 120 frames, ten seconds is 240. Below about 100 frames a sequence rarely holds on screen long enough to read.
Do I need an intervalometer?
Most cameras have one built in, and many can assemble the clip themselves. A separate one is only needed for very long intervals, or for exposures past 30 seconds where the camera is in bulb mode anyway.
My card fills before the end. What do I change?
Give the tool your card capacity and frame size, and it tells you the longest session that fits at this interval. Then either lengthen the interval, which costs clip length linearly, or shoot JPEG where the light is stable — roughly a third the size — and keep raw for the sunset.
Why is my sequence flickering?
Usually aperture flicker: the lens blades do not close to exactly the same place each frame. Shoot in manual, and on lenses that allow it use the detach-and-hold trick so the aperture stays wide open. Slow changes in light across a long sequence are fixed afterwards by a deflicker pass.
What is the holy grail, and what does the stops figure mean?
A holy grail timelapse runs from day into night in one sequence, across roughly ten stops of light. The figure in the evening block tells you how many stops that window loses and how often you must give one back — the rhythm of the shoot, in minutes.
Can I use the same frames for a star trail?
Yes, if the frames are long enough and the gap between them small enough. That is a different question with a different answer, and it belongs to the star trail calculator.
How do I turn the frames into a video?
Any editor will import a numbered sequence as a clip; command-line tools will do it in one line. Choose the playback rate at that moment — the table in the answer shows what each one gives.
Sources and further reading
- Time-lapse photography — the technique and its history.
- Twilight — civil, nautical and astronomical, the boundaries the evening window uses.
- Frame rate — why 24, 25, 30 and 60 are the rates on offer.
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