Time Lapse Calculator — Frames and Film Length

A time-lapse is two durations wearing one another’s clothes: the hours you shoot and the seconds you watch. Enter how long the scene runs, the interval between frames and the playback rate, and this calculator returns the frame count, the finished video’s length, and (from your photo size) the memory card the shoot will eat.

The Arithmetic of Compressed Time

Three quantities govern every time-lapse, and this calculator is their triangle: frames = shooting seconds ÷ interval; video seconds = frames ÷ frame rate; and the speed-up — the number the audience feels — is interval × frame rate (a 5-second interval at 24 fps plays life 120 times fast). Every creative choice in the genre is a point in that triangle. Shorter intervals buy smoother motion and longer finished clips at the price of storage, battery and shutter life; longer intervals compress grander spans (construction projects measured in months) into watchable minutes while movement strobes. The frame rate is nearly free creatively — the same frames re-time to any fps — which is why experienced shooters decide the interval in the field and the frame rate at the desk. The calculator’s storage line is not an appendix to that artistry; running out of card mid-sunset is the genre’s commonest ruined shoot, and it is always arithmetic that could have been done the day before.

Worked Example: Two Hours Over the Harbour

The defaults run a classic evening shoot: 2 hours of real time, a frame every 5 seconds, played at 24 fps. Frames = 7,200 ÷ 5 = 1,440 (the calculator counts 1,441, including the frame at time zero — a pedantry worth a frame). Video length = 1,441 ÷ 24 ≈ 60 seconds. Speed-up = 5 × 24 = 120×: clouds will sail, boats will dart, the light will fall at two minutes per second of screen time. Storage at RAW sizes (25 MB) lands near 36 GB — one fast card, or a JPEG decision, which the file-size input exists to price before the harbour does. Note how the triangle flexes: the same two hours at a 2-second interval yields a stately 2.5-minute film and 90 GB of RAW; at 15 seconds, a punchy 20-second clip on 12 GB. Same sunset, three films — chosen by one division.

Choosing the Interval: A Field Guide in One Paragraph

The interval’s job is to match the subject’s own tempo so motion reads as flow rather than strobe. Fast clouds and crowds: 1–2 seconds. Slow clouds, shadows, tides: 3–5. Sunsets and traffic: 2–5, tightening as the light falls. Plants and ice: minutes. Construction and seasons: minutes to hours, on mains power and weatherproofing, where this calculator’s frame counts (a 30-day build at 5-minute intervals is 8,640 frames and six minutes of film) become project plans. The governing test is the subject’s crossing time: a frame interval should be a small fraction of the time a subject takes to cross the frame, which is why the same 5 seconds that renders a harbour sublime renders a motorway strobing — speed lives in the scene, not in the number.

The Holy Grail: Day-to-Night and the Ramping Problem

The genre’s signature shot — sunset into city lights in one unbroken flow — is an exposure problem wearing this calculator’s arithmetic as a coat. Across a sunset the light falls four or more stops; the camera must ramp exposure smoothly (aperture, shutter or ISO choreographed by a ramping intervalometer or software) while the interval discipline holds, or the film strobes with each step change. The planning remains this page’s: the interval is chosen for the subjects (clouds and traffic), the frame count for the target duration, and the storage and power budgeted for both — with the ramping layered over as technique. It is worth knowing the summit exists when the basic triangle starts to feel routine: every element of the grail shot is a row in this calculator plus one exposure decision per frame.

Shutter Counts: The Camera’s Own Budget

One line the calculator does not print deserves its sentence: every frame is a shutter actuation, and shutters are rated in the low hundreds of thousands. A construction camera at 5-minute intervals accrues about 105,000 frames a year of continuous duty — a consumer body’s rated life in a single project, which is why dedicated time-lapse and construction cameras use electronic shutters or industrial mechanisms, and why mirrorless bodies’ silent electronic modes have become the genre’s default for long projects. Check the frame count this page returns against your body’s rating before a long deployment; the arithmetic of the film and the arithmetic of the machine are the same count, read by two different owners.

Phones and Apps: The Democratised Triangle

The phone in every pocket now runs this page’s triangle in silicon — its time-lapse mode fixes a frame rate (usually 30 fps playback) and adapts the capture interval to the recording length, lengthening the interval as the shoot grows so the output lands in a watchable band. The convenience costs the stills workflow’s freedoms (no RAW, no re-time, no rescue), but the planning questions survive the automation: how long will you shoot, what will it compress to, and will the battery and storage hold — the app answers silently with its own defaults, and this calculator answers out loud with yours. For the shoot that matters, the dedicated camera and the intervalometer remain the professional instruments; for everything else, knowing the triangle is knowing what the phone is doing on your behalf.

Related Tools

More from the Other Calculators hub: the Camera Field of View Calculator for framing the scene before compressing it, and the Playback Speed Calculator — the same trick played on finished media instead of life.

Frequently Asked Questions

How many photos do I need for a 30-second time-lapse?

At 24 fps, 30 seconds is 720 frames (750 at 25 fps, 900 at 30). Then the interval decides the shoot: 720 frames at 5 seconds is one hour of real time; at 2 seconds, 24 minutes. Work backwards from the deliverable as the professionals do — target duration to frames, frames times interval to shooting time — which is this calculator’s triangle read in reverse. Add a margin of frames at both ends for editing handles in the timeline; the calculator’s count is the scene itself, not the edit’s appetite or the client’s revisions.

What interval should I use for clouds?

By cloud speed: fast, low, wind-driven cumulus wants 1–2 seconds to move without teleporting; high, slow sheets take 3–5. The crossing-time test decides precisely: if a cloud crosses your frame in about two minutes of real time, a 2-second interval gives it sixty frames of journey — smooth. At 10 seconds it gets twelve positions and visibly jumps. When in doubt err short — surplus frames can be dropped or the clip re-timed faster in post; missing frames cannot be invented, which is the asymmetry that should govern every interval decision.

Why does my time-lapse flicker?

Flicker is frame-to-frame exposure or white-balance variation, usually the camera’s automation changing its mind: aperture-priority metering reacting to a passing cloud, auto white balance hunting, or — the subtle one — aperture blades stopping down inconsistently at small f-numbers. The craft defences are manual everything (exposure, focus, white balance locked), modest apertures, and deflicker tools in post. The calculator cannot fix flicker, but its frame budgets explain the modern mitigation of shooting more frames than needed and letting software average the sins away.

How long will my battery last?

By frames, roughly, not hours: mirrorless cameras typically deliver several hundred to about a thousand-plus frames per charge under time-lapse duty (live view and chimping tax it hard; DSLRs with optical finders sip by comparison), and intervalometers cannot conjure charge. For shoots beyond a few thousand frames the answers are dummy batteries on mains or USB power banks — priced against this calculator’s frame count, which is the honest unit of consumption. Cold weather halves the estimate and is the field’s oldest ambush after the full memory card.

RAW or JPEG for time-lapse?

RAW buys post-production latitude — exposure ramping through a sunset’s four stops of change is the classic use — at the storage and write-speed prices the calculator’s file-size input quantifies (36 GB versus about 9 in the worked example’s terms). JPEG buys endurance and simplicity, and modern sensors’ JPEG engines are good enough for most delivery. The professional compromise is RAW for hero shoots and small-medium JPEG for volume work; the calculator exists so the choice is made from the frame count outward, rather than discovered at frame 900 of 1,441.

What about the camera’s built-in time-lapse movie mode?

It performs this calculator’s arithmetic internally and delivers a finished video file — convenient, and binding: the interval and frame rate are frozen into a compressed clip, the individual frames often discarded, and the re-time and deflicker options of the stills workflow lost. For casual work it is the right tool. For anything destined for an editor’s timeline, shoot stills (intervalometer built-in or external) and keep the frames — the calculator’s storage line is the price of that freedom, stated in advance.