Time-Lapse Calculator

Background.

A time-lapse is four numbers that have to agree with each other: how long you shoot, how often you fire, how fast it plays back, and how long the finished shot runs. Fix any two and the others follow. This calculator solves whichever one you are missing, and then tells you the two things that actually derail shoots — how many frames that means, and how much card space they will eat.

The arithmetic is not this page's invention. Nikon's own time-lapse documentation states it in two sentences: the total number of frames is the shooting time divided by the interval and rounded up, and the length of the final movie is the number of shots divided by the frame rate. The rounding up is theirs too, which is why this page uses it rather than rounding to nearest — and Nikon's worked example, a 48-frame clip at 24p running about two seconds, is used here as a direct check.

Pick your way in depending on what is already fixed. If you have set the intervalometer and want to know what you will end up with, solve for the clip length. If the edit needs a ten-second shot and you know how long you can stay, solve for the interval. If the interval is dictated by the exposure — long-exposure night work, where each frame takes 25 seconds — and you know what the edit needs, solve for how long you have to stand there. All three routes report the same set of numbers.

The speed-up factor is the output most worth reading. It is shooting time divided by clip length, and it also equals interval multiplied by frame rate, which is a useful thing to know in the field: a five-second interval at 24 fps is always 120 times real time whatever else you change. That factor is what decides whether the motion looks right. Clouds want something in the region of 100 to 300 times; people and traffic look natural much slower, around 10 to 60 times; stars need to run in the thousands before the rotation reads as movement.

Card space is the output that ruins days. Two hours at a five-second interval is 1440 frames, and at 25 MB per raw file that is 35 GB — for one minute of footage. Shoot four such sequences and you have filled a 128 GB card. Enter a real file size from your own camera rather than a guess, because raw sizes vary by a factor of three between compressed and uncompressed, and between quiet and detailed scenes.

One limit the arithmetic cannot enforce for you: the interval has to be longer than the exposure plus the time the camera needs to write the file to the card. Ask for a three-second interval with a four-second exposure and the intervalometer will quietly skip frames, and your clip will come out short and stutter. Nikon also caps time-lapse movies generated in-camera at 20 minutes, which is far longer than any edit will use but worth knowing if you are letting the camera assemble the clip rather than shooting stills and rendering later.

Below the widget you will find the derivation, three worked examples computed by hand, the standard frame rates and where the odd 23.976 and 29.97 figures come from, and practical interval guidance by subject.

What is time-lapse calculator?

A time-lapse is a sequence of stills captured at a fixed interval and played back at a normal frame rate, so that time appears compressed. Four quantities describe it completely and any two fix the rest. The shooting duration D is how long the camera runs. The interval I is the gap between frames. The frame rate R is the playback rate. The clip length L is what the audience sees. The relations, taken from Nikon's own time-lapse documentation, are: frames N = ceil(D ÷ I), and L = N ÷ R. From those, the speed-up factor is D ÷ L, which simplifies to I × R — so a 5-second interval rendered at 24 fps always runs at 120× real time regardless of how long you shoot. Frame rate is a rendering choice rather than a capture one: the same 1440 frames make a 60-second clip at 24 fps, a 57.6-second clip at 25 fps and a 48-second clip at 30 fps. The frame count is also the shutter actuation count, which matters on a body with a mechanical shutter rated for a few hundred thousand cycles, and it drives the storage requirement directly. What none of this arithmetic can tell you is whether the interval is physically achievable: the camera must finish the exposure and write the file before the next frame is due, so the interval sets a hard ceiling on exposure time, and long-exposure night sequences are interval-limited rather than duration-limited.

How to use this calculator.

1. 01Choose what to solve for. Clip length is the "what will I get?" question, interval is the "what do I set?" question, and shooting time is the "how long am I here?" question.
2. 02Enter the playback frame rate you will render at. 24 is cinematic, 25 is European broadcast, 30 is common online. The 23.976, 29.97 and 59.94 variants exist because ITU-R BT.2100 defines them as 24/1.001, 30/1.001 and 60/1.001.
3. 03Enter the two quantities your mode needs. Shooting time is in minutes, interval and target clip length are in seconds.
4. 04Enter a realistic per-frame file size. Photograph one frame at your intended settings and read the actual size off the card rather than guessing — compressed and uncompressed raw differ by a factor of two or more, and a detailed scene inflates both.
5. 05Check the interval against your exposure. It must exceed the exposure time plus the file write time, with margin. A four-second exposure needs at least a six-second interval on most bodies, and more on a slow card.
6. 06Read the speed-up factor to sanity-check the motion. Clouds usually want 100–300×, traffic and people 10–60×, stars 1000× and up. If the factor is far from those, change the interval rather than the frame rate.
7. 07Check the card space before you start, not after. Multiply by the number of sequences you plan to shoot that day, and remember that a card should never be filled to the last gigabyte.
8. 08Shoot longer than the calculator says. Batteries fade, light changes, someone walks through the frame, and an edit that needs ten seconds is far happier being handed fifteen.

The formula.

The two core relations are quoted directly from Nikon's time-lapse documentation:

"The total number of frames in the final movie can be calculated by dividing the shooting time by the interval and rounding up." "The length of the final movie can then be calculated by dividing the number of shots by the frame rate selected for Frame size/frame rate."

So N = ceil(D ÷ I) and L = N ÷ R. The rounding up is the manufacturer's stated rule, and it is why 100 seconds at a 3-second interval gives 34 frames rather than 33 — the last, partial interval still fires a frame. Nikon's own example is the check this page's tests use: a 48-frame movie at 24p is about two seconds long, and 48 ÷ 24 = 2.

The speed-up factor falls out and simplifies pleasingly:

speed-up = D ÷ L = D ÷ (D ÷ I ÷ R) = I × R

So it depends only on the interval and the frame rate, not on how long you shoot. A 5-second interval at 24 fps is 120× real time whether you run for ten minutes or ten hours. That is the single most useful thing to carry in your head, because it means you can choose the look from the interval alone and then decide the duration purely from how long a clip you want.

Storage is N × S, converted to gigabytes of 1024 megabytes because that is the unit card capacities and camera counters use.

When the page solves backwards it computes the frame count first in every mode. For the interval, N = ceil(L × R) and then I = D ÷ N; for the shooting duration, N = ceil(L × R) and then D = N × I. Doing it in that order matters: deriving the interval first and then re-applying the ceiling could land the division a hair above an integer at twenty significant digits and invent a spurious frame. Computing the integer first makes every mode internally exact and reversible.

On frame rates, the odd numbers have a precise origin. Recommendation ITU-R BT.2100-3 lists the permitted frame frequencies as "120, 120/1.001, 100, 60, 60/1.001, 50, 30, 30/1.001, 25, 24, 24/1.001". The 1.001 divisor is a legacy of the NTSC colour subcarrier, and it is why 24 fps has a 23.976 sibling, 30 has 29.97 and 60 has 59.94. They are not approximations of round numbers; the round numbers divided by 1.001 are the exact definitions. The field on this page takes a plain number so any of them can be entered directly.

What the arithmetic cannot check for you is physical feasibility. The camera must complete the exposure and write the file before the next frame is due, so the interval imposes a ceiling on exposure time. A 25-second exposure for a star sequence needs an interval of at least about 30 seconds on a fast card, which in turn fixes the speed-up factor at roughly 720× at 24 fps and means a 10-second clip demands two hours of shooting. Night time-lapse is interval-limited, and this is the arithmetic behind why.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Nikon Corporation. D7500 Online Manual, 'Time-Lapse Movie'. The source of the algorithm this calculator implements: 'The total number of frames in the final movie can be calculated by dividing the shooting time by the interval and rounding up' and 'The length of the final movie can then be calculated by dividing the number of shots by the frame rate selected for Frame size/frame rate', with the worked example 'A 48 frame movie recorded at 1920 × 1080; 24p, for example, will be about two seconds long' and the note that 'The maximum length for time-lapse movies is 20 minutes.'
2. [2]International Telecommunication Union. Recommendation ITU-R BT.2100-3 (02/2025), 'Image parameter values for high dynamic range television for use in production and international programme exchange', Table 1 — Image spatial and temporal characteristics. The Frame frequency (Hz) row reads '120, 120/1.001, 100, 60, 60/1.001, 50, 30, 30/1.001, 25, 24, 24/1.001', which is where 119.88, 59.94, 29.97 and 23.976 fps come from.
3. [3]Nikon Corporation. D7500 Online Manual, Technical Notes — Specifications. Gives the shutter range as '1/8000–30 s in steps of 1/3 or 1/2 EV, bulb, time, X250' and sensitivity as 'ISO 100–51200' — the limits that bound how long an individual time-lapse frame can be and therefore how short the interval can be.
4. [4]Canon Inc. EOS R7 Product Manual, Specifications. Gives shutter speeds of '1/8000–30 sec., Bulb' with the mechanical shutter and '1/16000, 1/8000–30 sec., Bulb' with the electronic shutter, and a metering range of 'EV –2 to 20' — the electronic-shutter option being the one that costs no mechanical actuations across a long sequence.
5. [5]Camera & Imaging Products Association / JEITA. CIPA DC-008-2012 (JEITA CP-3451C), Exif Version 2.3, Annex C — APEX Units. Defines the stop used throughout this page's exposure discussion: ShutterSpeedValue Tv = −log₂(exposure time), so one unit is one doubling of exposure time, which is the unit in which interval-versus-exposure trade-offs are reasoned.