Photography Calculator

A time-lapse compresses a long stretch of real time into a short video by taking one frame every few seconds and then playing those frames back at normal speed. Three numbers govern the whole plan and they're locked together by one relationship: frames = real duration ÷ interval, and frames = playback FPS × clip length. Pin down the interval, the FPS, and any one of the three quantities {frame count, shoot duration, clip length}, and the other two are fixed.

The interval is your shutter-press rhythm and it sets how fast the world appears to move in the final clip. Short intervals (1–2 seconds) suit fast subjects like traffic or scudding clouds; longer intervals (15–30 seconds) suit slow ones like sunsets, construction, or stars wheeling overhead. Pick the interval for the subject first, because it's the parameter with a creative right answer — the other numbers follow from it.

Playback FPS is the speed your editor renders the clip at, and it does double duty: it sets how smooth the motion looks and, combined with the frame count, how long the finished video runs. At 24 or 30 FPS the motion is cinematic and smooth; lower FPS looks choppier. Because clip length = frames ÷ FPS, a fixed pile of frames plays back shorter at a higher FPS — there's an inherent trade between smoothness and runtime that this calculator makes explicit.

Plan it from whichever end you actually know. Heading out for a fixed window? Enter the shoot duration and read off how many frames you'll fire and how long the clip will be. Need a clip of an exact length for an edit? Enter the clip length and FPS to learn the frame count, then multiply by the interval to see how long you must shoot — and check that against your battery and card. The frame count is also the line to watch for storage: at typical raw sizes, a few thousand frames is real space.