# Film Calculator

Created by Krishna Nelaturu
Reviewed by Dominik Czernia, PhD candidate and Steven Wooding
Last updated: Dec 08, 2021

Our film calculator helps you calculate the length of the film needed if you know the video's run time you shall shoot. You can also determine the maximum video length you can capture with a specific film length or compare these properties among different film formats before choosing the right one.

Are you curious how film length and run-time are related and why they depend on the film format? Are you perplexed with terms like film feet, film format, frames per foot, and frames per second? Congratulations on coming to this feet and frames calculator to find the answers!

The length of the film needed for a specific run-time of the video is given by:

$\footnotesize \text{film length} = \text{run-time} \cdot \frac{\text{fps}\cdot 60}{\text{frames per foot}}$

where:

• $\text{film length}$ – Length of the film in feet (ft);
• $\text{run-time}$ – Total run-time of the video in minutes;
• $\text{fps}$Frames per second – the number of frames captured by the camera per second; and
• $\text{frames per foot}$ – The total number of frames in the film per foot.

Similarly, you can tell the number of frames required to capture a given run-time or the number of frames in a given length of the film through the following relations:

\quad \footnotesize \begin{align*} n_{frames} &= \text{run-time} \cdot \text{fps}\cdot 60\\ n_{frames} &= \text{film length} \cdot \text{frames per foot} \end{align*}

where:

• $n_{frames}$ – Total number of frames captured in a given run-time or film length.

Check out our timecode calculator or timecode to frames calculator to see how video frames fit into timecodes!

The quantity $\text{frames per foot}$ varies with the type of film format used in the camera. So if you know the speed at which your camera is recording and the type of film format, you can determine film length or run-time if you know one of them.

For example, if you want to calculate the 16 mm film required to capture 1 hour (60 min) of video at $30 \text{ fps}$, then you'd get:

\quad \begin{align*} \text{film length} &= 60 \cdot \frac{30 \cdot 60}{40} \\ &= 2700 \text{ ft} \end{align*}

You can also use this 16 mm film calculator to obtain the same result with no sweat. The length of the film used to capture one minute of run-time is called $\text{feet per minute}$, and evidently, it is given by:

$\footnotesize\quad\text{feet per minute} = \frac{\text{fps}\cdot 60}{\text{frames per foot}}$

This quantity is useful to quickly estimate the run-time you can capture with the feet of film available. For example, if you're purchasing a $400 \text{ ft}$ roll of 16 mm film, and you're aware that it has $36 \text{ feet per minute}$ at 24 fps, then you can estimate that you can capture a total run-time of $\frac{400}{36} = 11.11 \text{ min}$ or 11 min 6 sec.

## Film calculations in meters

Although we usually measure the film length in feet, we can use meters instead. For this purpose, we use the quantities $\text{frames per meter}$ and $\text{meters per minute}$:

\footnotesize \begin{align*} \text{film length} = \text{run-time } \cdot &\frac{\text{fps}\cdot 60}{\text{frames per meter}}\\\\ \text{meters per minute} = &\frac{\text{fps}\cdot 60}{\text{frames per meter}} \end{align*}

Keep in mind that $\text{film length}$, in this case, is also expressed in meters.

## Film formats, frames per foot and frame rate

Since the invention of film cameras, the film industry has developed various film formats with different characteristics and advantages. Among them, 16mm and 35mm have been widely popular choices since their introduction. While they may seem irrelevant in the era of digital cameras, film cameras are still in use for their detail, color accuracy, and other benefits. Nowadays, almost all film cameras use 35mm, 4-perf format, otherwise known as 35 mm format.

Each film format has a different aspect ratio (frame size) and a different number of frames in each foot of the film, given by $\text{frames per foot}$. The following table shows the $\text{frames per foot}$ for different film formats, which we used in this feet and frames calculator.

Frames per foot and per meter for different film formats.

Film format

Frames per foot

Frames per meter

8 mm

80

264

Super 8

72

236.21

16 mm

40

131.23

35 mm, 2-perf

32

105

35 mm, 3-perf

21.33

70

35 mm, 4-perf

16

52.5

65 mm, 5-perf

12.8

42

The term "perf" refers to the perforations in the film, also called sprocket holes, used to move the film through the camera with sprockets. The speed at which the camera captures the video is the frame rate, measured in frames per second (fps). The industry adopted 24 fps as the standard speed for sound films.

When you choose the film format in our film calculator, it uses the corresponding $\text{frames per foot}$ in its calculation.

💡 Did you know? Standard film roll size for 16 mm film is 400 ft, and for 35 mm film is 1000 ft, because at 24 fps, they both shoot approximately equal amount of run-time (around 11 mins). If you want to see how many 400 ft or 1000 ft rolls you will need for your work, you can do so using our tool's advanced mode!

## How to use this film calculator

You can use our film calculator to calculate feet, frames, or meters of film length needed to shoot your video:

• Choose the type of film format and enter the fps of your camera.
• Give the film length, frames, or run-time to get the remaining values.
• You can change the film format and see how different the results are.
• In the advanced mode, you can see how many rolls of 1000 ft or 400 ft film you need for the corresponding film length.
Krishna Nelaturu
Film format
35 mm, 4-perf
Frame rate
fps
Film length
ft
Frames
Run-time
hrs
min
sec
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