Film Calculator

Convert film footage to running time (and see total frames and reel speed) for 35mm, 16mm, Super 8, or Standard 8 stock at any frame rate.

Quick Facts

Frames per foot
35mm = 16, 16mm = 40, Super 8 = 72, Standard 8 = 80
Fixed by frame size and perforation pitch for each gauge.
Standard sound speed
24 frames per second
The projection standard since sound film became universal in the late 1920s.
35mm rule of thumb
90 feet per minute
At 24 fps, 35mm film (16 fpf) runs 90 ft every minute of screen time.

Your Results

Calculated
Running time
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H:MM:SS of on-screen footage
Running time (minutes)
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Decimal minutes, for scheduling
Total frames
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Frames exposed, excluding leader
Feet per minute
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Reel speed at this gauge & frame rate

Ready

Choose a film gauge, enter footage and frame rate, then press Calculate.

About the Film Calculator

This tool converts physical film footage into running time using the standard frames-per-foot (fpf) and frame-per-second (fps) relationship that film labs, editors, and archivists have used for decades. It also reports total frame count and the reel's feet-per-minute speed, which is handy for splicing, shipping, and scheduling.

The formula

Every film gauge has a fixed number of frames printed per foot of stock, set by the frame size and perforation spacing for that format:

  • 35mm (4-perf): 16 frames per foot
  • 16mm: 40 frames per foot
  • Super 8mm: 72 frames per foot
  • Standard 8mm: 80 frames per foot

Net footage (total footage minus head/tail leader) multiplied by the frames-per-foot constant gives total frames. Dividing total frames by the frame rate (frames per second) gives total running time in seconds:

Running time (seconds) = (Footage − Leader) × Frames per foot ÷ Frame rate (fps)

For example, 990 net feet of 35mm film (16 fpf) contains 15,840 frames. At the standard sound speed of 24 fps, that is 660 seconds — exactly 11 minutes.

Frame rate matters

Sound film has been projected at 24 fps since the format standardized in the late 1920s. Silent-era film was often shot and projected slower, commonly 16-18 fps, so silent footage timed at 24 fps will read shorter than it actually ran. Video-originated transfers in PAL regions commonly use 25 fps. Always match the frame rate to how the footage was actually shot or is meant to be projected.

Why leader footage is excluded

Leader is blank or non-picture film spliced onto the head and tail of a reel for threading, protection, and countdown marks. It passes through the projector or scanner but carries no image, so it is subtracted from total footage before computing on-screen running time — otherwise the running time would be overstated.

Frequently Asked Questions

How is film footage converted to running time?
Multiply net footage (total minus leader) by the frames-per-foot constant for the film gauge to get total frames, then divide by the frame rate in fps to get total seconds. For example, 990 feet of 35mm film (16 fpf) has 15,840 frames; at 24 fps that is 660 seconds, or exactly 11:00.
Why do different film gauges have different frames-per-foot values?
Frames-per-foot depends on frame size and perforation pitch, which vary by format. Standard values are 16 frames per foot for 35mm (4-perf), 40 for 16mm, 72 for Super 8, and 80 for Standard 8 (regular 8mm).
What frame rate should I use?
Use 24 fps for standard sound film, 25 fps for PAL-region video-originated transfers, or the silent-era speed of 16-18 fps if you are timing archival silent footage. Always match the rate the footage was actually shot or intended to project at.
What is leader footage and why subtract it?
Leader is blank or non-picture film spliced onto the head and tail of a reel for threading and protection. It runs through the projector or scanner but shows no image, so it is subtracted from total footage before computing on-screen running time.

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