timelapse Timelapse Calculator star

How It Works

Timelapse math starts from what the finished clip should look like: frames needed = target clip length (seconds) × playback frame rate (fps). Once you know how many frames the edit requires, divide the real duration of the event by that number to get your shooting interval: interval (seconds) = real event duration (seconds) ÷ frames needed.

Worked example: a 10-second, 30 fps clip of a 3-hour sunset needs 10 × 30 = 300 frames. The event lasts 3 × 3600 = 10,800 seconds, so interval = 10,800 ÷ 300 = 36 seconds — fire the shutter roughly every 36 seconds and the footage compresses cleanly into the target length.

The number this gives you is only half the job — the interval also has to match how fast the subject actually moves. Slow-changing scenes (drifting clouds, a sunset's color shift, plant growth) tolerate long intervals because little changes between frames. Fast subjects (pedestrians, traffic, a construction crew) need short intervals; stretch the interval too far and motion turns into a stroboscopic, "jerky" jump-cut instead of smooth flow. Go the other way — too short an interval on a slow subject — and you waste storage and shooting time on near-identical frames, producing an oddly "over-smooth" or static-feeling clip. The arithmetic is exact; matching the result to the subject's motion speed is still a judgment call.

What to Know

Storage is the other constraint worth planning before you start: 300 RAW files at roughly 30 MB each is about 9 GB for a single 10-second clip — multiply that across several setups in a shoot day and cards fill fast. JPEG keeps files far smaller and is the common default for timelapse unless heavy exposure or color grading is planned in post, in which case RAW's extra latitude is worth the space.

One more check worth doing before a long shoot: multiply your interval by the frames needed to confirm total shooting time actually fits your battery life and card capacity. A 6-hour star-trail sequence at a 40-second interval needs roughly 540 frames spread across those 6 hours — easily enough to outlast a single battery charge, so a spare battery, external power or a dedicated intervalometer with its own power supply is worth planning for alongside the interval itself.

• Match the interval to subject speed, not just the arithmetic result.
• Shoot in full manual mode so the camera can't re-meter between frames.
• Decide RAW vs JPEG based on how much grading you plan afterward.