In this article6 sections
A film is really a very fast slideshow. A camera captures a series of still pictures, called frames, and a projector or screen shows them one after another. Do it quickly enough and your brain blends them into smooth motion.
For nearly a hundred years, the standard speed for cinema has been 24 frames per second. That number wasn’t chosen because it’s perfect for our eyes. It was chosen because of sound, and money.
The silent era: no fixed speed
The earliest cameras and projectors were often cranked by hand, so the speed depended on the person turning the handle. Films could be shot at one speed and shown at another, which is partly why old silent films can look jerky or sped up today.
As cameras improved, about 16 frames per second became a common, unofficial standard. It was roughly the cheapest speed that still looked smooth enough, because film stock was expensive and every extra frame cost money.
Sound changed everything
In the late 1920s, films began to talk. Early hits such as Don Juan (1926) and The Jazz Singer (1927) used Warner Bros.’ Vitaphone system, and Fox launched its own system, Movietone.
Sound brought a new problem. If the film ran at a different speed each time, the voices and music would change pitch. Speeds had to be fixed and exact. And when sound was printed on the film itself, it needed the film to move fast enough to record it clearly.
Both Vitaphone and Movietone ran at 24 frames per second. Engineers had found it was about the lowest speed that didn’t harm sound quality, which also made it the cheapest. Other systems used slightly different rates, but 24 became the industry standard as sound took over.
24 frames per second wasn’t picked because it’s perfect for our eyes. It was the cheapest speed that kept the sound clear.
The trick that stops flicker
You might expect 24 pictures a second to look flickery, and in a way it would. If the screen went dark only 24 times a second, many people would see an annoying flicker.
So film projectors use a spinning shutter that blocks the light twice for every frame: once while the film moves on to the next picture, and once more in the middle. Each frame is flashed twice, giving 48 flashes a second, which is fast enough that most people see a steady image.
Why 24 still looks like “cinema”
Over the decades, 24 frames per second became more than a technical standard. It became a look.
At 24 frames, each picture is usually exposed for about a forty-eighth of a second, so anything moving quickly is slightly blurred. That soft motion blur helps the frames blend together and gives films their familiar dreamy quality.
Show the same scene at a much higher frame rate and the movement becomes sharper and smoother. Some viewers love it. Many say it looks less like cinema and more like a TV programme or home video. It’s the same reaction people have to the motion smoothing setting on many televisions, which creates extra in-between frames and is often nicknamed the “soap opera effect”.
Attempts to go higher
Filmmakers have tried to move beyond 24 several times:
- Peter Jackson shot *The Hobbit* films (2012–14) at 48 frames per second. Some audiences found the sharper picture distracting, and the format didn’t catch on.
- Ang Lee went further, shooting *Billy Lynn’s Long Halftime Walk (2016) and Gemini Man* (2019) at 120 frames per second.
- James Cameron’s *Avatar: The Way of Water* (2022) used a higher frame rate for some scenes, such as fast action and underwater shots, and 24 for others.
High frame rates can look superb for fast action, sport and 3D. But for most dramas and comedies, directors still choose 24, because it looks like what audiences expect a film to look like.
Frame rates on TV and online
Television grew up with different standards, linked to how electricity is supplied in different countries:
- In the UK, Europe, India and many other countries, TV traditionally ran at 25 frames per second. Films shown on these channels were often simply played about 4% faster, which made them slightly shorter and raised the pitch a little.
- In North America and Japan, TV ran at about 30 frames per second, and films were adapted using a technique that repeats some frames.
Online video and video games often use 30 or 60 frames per second, or more, because sharp, smooth movement suits sport, gaming and screen recordings.
Frequently asked questions
Can the human eye see more than 24 frames per second?
Yes. 24 is not the limit of human vision. People can easily tell the difference between 24, 60 and 120 frames per second, especially in fast movement. 24 is simply the point where motion looks smooth enough, with a little blur.
Are films still shot on film?
Most are now shot digitally, and digital cameras can record at almost any frame rate. Directors usually still choose 24 for the look, and some still shoot on film by choice.
Why do old silent films look sped up?
Many were shot at slower speeds than 24, sometimes cranked by hand. When they’re shown at a faster modern speed, everything moves too quickly. Careful restorations play them at the speed they were meant to be seen.
