About the Timelapse Calculator
This timelapse calculator plans a time-lapse shoot in either direction. Tell it how long the event lasts and the interval between shots to see how many photos you will take and how long the finished clip will be, or tell it how long you want the clip to run and it will work out the interval to set on your intervalometer. It also shows the speed-up factor and how much memory-card space the sequence will need.
Use it for sunsets, cloudscapes, star trails and Milky Way sequences, construction projects, cityscapes, plants growing and event set-ups. Knowing the shot count in advance tells you whether one battery and one card will last, and the speed-up factor helps you choose an interval that suits the subject — fast clouds look best at 1–3 seconds, sunsets at 3–10 seconds, and slow builds at minutes.
The calculator assumes one photo per interval for the whole event and that each photo becomes one video frame. Keep your shutter speed shorter than the interval (with a second or so to spare) so the camera has time to write each file.
How to use the timelapse calculator
- 1Choose whether to solve for clip length or for the interval.
- 2Enter how long the event lasts in hours and minutes.
- 3Enter your interval, or the clip length you want to end up with.
- 4Pick the playback frame rate and the typical size of one photo.
- 5Read the shot count, clip length, speed-up and storage, and set your intervalometer.
Formula and method
Every photo becomes one frame of video. Over an event lasting T seconds, shooting every i seconds gives T ÷ i photos (rounded down to whole shots). Dividing the photo count by the playback frame rate gives the clip length in seconds. To hit a target clip length instead, multiply the clip length by the frame rate to get the number of photos needed and divide the event duration by that number to get the interval.
The speed-up factor is the interval multiplied by the frame rate: at 5-second intervals played at 30 fps, each second of video shows 150 seconds of real time. Storage is the number of photos times the average file size, in decimal gigabytes (1 GB = 1,000 MB) as memory cards are labelled.
- T
- Event duration in seconds
- i
- Interval between shots in seconds
- fps
- Playback frame rate
- clip
- Finished clip length in seconds
Worked examples
Two-hour cityscape at 5-second intervals
Two hours is 7,200 seconds; one shot every 5 seconds gives 1,440 photos. At 30 fps they make a 48-second clip that runs 150× faster than real life, and 1,440 raw files of 25 MB need 36 GB of card space.
20-second sunset clip from 90 minutes at 24 fps
A 20-second clip at 24 fps needs 480 frames. Spreading 480 shots over 5,400 seconds means one every 11.25 seconds, so each second of video covers 270 seconds of the sunset. The photos need 12 GB at 25 MB each.
Overnight star-trail sequence
Eight hours is 28,800 seconds; with 30-second exposures back to back that is 960 photos. At 25 fps the clip lasts 38.4 seconds and shows 750 seconds of sky per second, and 960 × 30 MB = 28.8 GB.
Frequently asked questions
What interval should I use for a timelapse?+
Match the interval to how fast the subject changes: 0.5–2 s for fast clouds, traffic and crowds; 3–10 s for sunsets, sunrises and slow clouds; 15–30 s for stars and the Milky Way (often limited by exposure length); and minutes or hours for construction or plants growing.
How many photos do I need for a 10-second timelapse?+
Multiply the clip length by the frame rate: 10 seconds at 24 fps needs 240 photos, at 25 fps 250 and at 30 fps 300. Shoot a little extra so you can trim the start and end.
What shutter speed should I use for a timelapse?+
For smooth motion, many shooters use an exposure about half the interval (a “180-degree” look), which may need an ND filter in daylight. The exposure must always be shorter than the interval, with time left for the camera to save the file.
Should I shoot timelapse in raw or JPEG?+
Raw gives far more latitude for exposure and white-balance corrections and for smoothing flicker, but files are two to four times larger and need a faster card. JPEG is fine for simple, evenly lit scenes and long sequences where storage is tight.
What frame rate is best for timelapse playback?+
24 or 25 fps gives a cinematic look and needs the fewest photos; 30 fps is common for online video. Higher rates such as 60 fps look smoother but need twice as many photos for the same clip length.