Frames to seconds and video frame rates explained: FPS chart, timecode, slow motion and shutter

Frame rate looks like a simple number, and then you try to mix a 25 fps clip from a European camera with a 29.97 fps clip from an American one, or shoot at 120 fps for slow motion and discover that your timeline is running at 24. Suddenly the number decides whether footage plays smoothly, drifts out of sync, or looks like a home movie from another decade.

This guide explains what frame rate is, how to convert frames to seconds and back, why the odd figures such as 23.976 and 29.97 exist, how timecode and drop-frame work, how to plan slow motion, how shutter speed relates to frame rate, and what happens when you convert between rates. Along the way, the FPS Calculator handles the arithmetic, and can even measure the real frame rate of a video file in your browser.

What frame rate actually measures

Frame rate is the number of still pictures shown each second. Show enough of them in sequence, and the brain reads the changes as motion. Each frame lasts for a fixed slice of time, and that slice is simply one second divided by the rate.

How to convert frames to seconds

Divide the number of frames by the frame rate. That is the whole formula:

seconds = frames ÷ fps

• 525 frames at 30 fps = 525 ÷ 30 = 17.5 seconds. As timecode that is 00:00:17:15, because 0.5 of a second is 15 of the 30 frames.
• 1,987 frames at 60 fps = 1,987 ÷ 60 = 33.117 seconds (33 seconds and 7 frames).
• 258 frames at 30 fps = 8.6 seconds, and 6,822 frames at 23 fps = 296.609 seconds, just under 5 minutes.

A single frame at 30 fps lasts 1 ÷ 30 = 0.0333 seconds, or 33.33 milliseconds. The frames to seconds calculator gives the seconds, the clock time (HH:MM:SS.mmm) and the SMPTE timecode at once, and has a copy button on each value.

How to convert seconds to frames

Go the other way by multiplying: frames = seconds × fps. Convert minutes and hours to seconds first.

• 1 minute at 15 fps = 60 × 15 = 900 frames.
• A 40-minute film at 24 fps = 2,400 × 24 = 57,600 frames; the same 40 minutes of 13 fps animation is 31,200 frames.
• A 2-hour movie at 24 fps = 7,200 × 24 = 172,800 frames.

When the answer is not a whole number, for example 10 seconds at 23.976 fps (239.76 frames), the nearest whole frame is what an editor will actually cut on. The calculator's Time → frames tab shows both the exact and the rounded value, accepts a pasted timecode, and lists the same length at 24, 25, 30 and 60 fps.

Frames per second chart

Frame counts for common lengths, so you can look up an answer without doing the sum:

12 and 15 fps are common in hand-drawn animation (drawing “on twos” at 24 fps gives 12 new pictures a second) and in stop motion, where every frame is posed by hand.

Why 23.976 and 29.97 exist

Early black-and-white American television ran at exactly 30 frames per second, matching the 60 Hz mains supply. When colour was added in the 1950s, the engineers had to fit the colour signal without disturbing existing sets. The solution slowed the rate very slightly, by a factor of 1000/1001, giving 29.97 frames per second. The same factor applied to 24 gives 23.976, and to 60 gives 59.94.

The difference sounds trivial and is not. A clip that really runs at 29.97 fps but is labelled 30 will be out of step with the wall clock by about 3.6 seconds every hour, or 108 frames. Broadcast timecode solved this with drop-frame counting: it skips the labels 00 and 01 at the start of every minute, except every tenth minute. No picture is discarded; only the numbers are omitted so that the timecode stays close to real time.

SMPTE timecode and drop-frame, simply

SMPTE timecode labels every frame as HH:MM:SS:FF: hours, minutes, seconds and the frame number within that second. At 25 fps the last field runs from 00 to 24, at 30 fps from 00 to 29. Editors use it because a frame label never changes, while “17.5 seconds” can land between two frames.

Drop-frame timecode is written with a semicolon, HH:MM:SS;FF. At 29.97 fps, frame number 1,800 is labelled 00:01:00;02, not 00:01:00;00, because the labels ;00 and ;01 were skipped at the one-minute mark. At the ten-minute mark nothing is skipped, so frame 17,982 is exactly 00:10:00;00. At 59.94 fps four labels are skipped instead of two. Over an hour this keeps the timecode within a few frames of the clock.

Adding up timecodes by hand goes wrong at exactly these skipped labels. The calculator's Timecode math tab adds or subtracts two timecodes at any rate, with drop-frame handled, and gives the result as timecode and as a frame count.

How to choose a frame rate

There is no correct answer, only a match between content, destination and taste:

• Narrative and cinematic work: 24 or 23.976 fps. The slight motion blur and stutter is the look audiences associate with film.
• Talking heads, tutorials and vlogs: 25 or 30 fps. Nobody notices the difference, and files stay modest.
• Gameplay, sport and action: 50 or 60 fps, where clarity of fast motion outweighs cinematic feel.
• Regional standard: Areas with 50 Hz mains supply traditionally use 25 and 50 fps, and 60 Hz regions use 30 and 60. Matching the local standard avoids conversion for broadcast delivery.

Higher frame rates cost data. YouTube's published upload guidance for 1080p standard dynamic range suggests about 8 Mbps at 24 to 30 fps and 12 Mbps at 48 to 60, an increase of half. Doubling the frames does not double the bitrate because codecs store only differences, but the cost is real. The Video Resolution Calculator shows the suggested bitrate for both ranges at any size.

Planning slow motion

Slow motion is not a special effect. It is footage recorded with more frames than the timeline uses. Play 120 recorded frames each second back at 24 frames per second, and every real second stretches across five seconds on screen. The formula is one line:

Slow-down factor = shooting fps ÷ timeline fps

Work backwards when you already know the effect you want. A 4× slow-down on a 25 fps timeline needs 100 fps footage. The slow-motion tab does this in both directions and also shows how long a real-time moment will last once stretched, which helps you decide how much to shoot.

Editing software can also create slow motion from ordinary footage by inventing in-between frames. The results are convincing on smooth movement and full of artefacts on fast or overlapping motion, so real high-frame-rate footage remains the better source when you can get it.

Shutter speed and the 180-degree rule

Frame rate controls how many pictures per second you take. Shutter speed controls how long each one is exposed, and that decides motion blur. The traditional guideline is the 180° rule, borrowed from film cameras whose rotating shutter was open for half of each frame: exposure is 1 divided by twice the frame rate.

A faster shutter gives crisp, staccato motion, the look of war footage and some sports. A slower one smears movement. Lighting adds a wrinkle: under artificial lights powered by 50 Hz mains, brightness pulses 100 times a second, and by 60 Hz mains 120 times. Choosing shutter speeds that match, such as 1/50 or 1/100 in 50 Hz regions and 1/60 or 1/120 in 60 Hz ones, avoids visible flicker and rolling bands.

Converting between frame rates

Trouble starts when rates meet. There are two very different ways to change one, and confusing them is the source of most timing problems.

• Re-labelling (conforming). Play the same frames at a different rate. Nothing is added or dropped, but speed and duration change. Playing 25 fps footage at 24 makes it 4% slower and the running time 4% longer, and film-to-PAL transfers historically ran the other way. Audio pitch shifts too, by about 0.7 of a semitone, unless it is corrected.
• Resampling. Keep the speed and duration and let the software duplicate, drop or blend frames. Going from 24 to 30 fps uses a 3:2 cadence where four film frames become five video frames. Going down drops roughly one frame in every few.

A worked example: 100 frames of 50 fps footage. To keep the same 2-second length at 25 fps, every other frame is dropped and you get 50 frames. To conform it instead, all 100 frames are played at 25 fps: the clip lasts 4 seconds and runs at 50% speed, which is exactly how 50 fps footage becomes smooth half-speed slow motion. 60 to 30 fps works the same way.

The Convert frame rate tab shows both outcomes side by side for any frame count or length: the new frame count when the length stays the same, and the new length and speed when the frames stay the same.

Calculating speed from video frames

If you know how far something moved and how many frames it took, you know its speed: speed = distance ÷ (frames ÷ fps). A car that covers 19.38 m in 18 frames of 30 fps video took 18 ÷ 30 = 0.6 seconds, so it was doing 19.38 ÷ 0.6 = 32.3 m/s, or 116.28 km/h (72.3 mph).

Two cautions. Measure the distance in the real world (lane markings, a known wheelbase), not on screen, and count frames from the same point on the object. One frame either way changes this example by about 6%, so a higher frame rate gives a more trustworthy answer. The Speed from frames tab does the sum in metres, kilometres, feet or miles.

Variable frame rate and mixed timelines

Phones and screen recorders often save variable frame rate video, in which the gap between frames changes with the scene. It saves space but can cause audio drift and stuttering in editors that expect a constant rate. If a clip misbehaves, note its average rate with the calculator's file measurement, then convert it to a constant rate before editing. The Video Converter can re-encode a clip at a chosen frame rate.

As a rule, set your timeline to the rate of most of your footage and the rate of the delivery format, and only mix in others deliberately, for example high-speed clips for slow motion.

Measuring the frame rate of a file

The FPS Calculator can read the frame rate from a video. It plays the clip muted for about two seconds and records the time each decoded frame is presented, then takes the typical gap and snaps it to the nearest standard rate. It works in browsers that support frame callbacks, including Chrome, Edge and Safari. Variable frame rate files can measure slightly off their average, so treat the result as a strong hint and confirm it in your editor when precision matters. Nothing is uploaded during this process.

Three myths worth dropping

• “Higher is always better.” Sixty frames can make a drama feel like a live broadcast, and it doubles the work for editing and storage.
• “Upconverting to 60 fps makes footage smoother.” Duplicating or blending frames cannot restore the motion information that was never captured.
• “Platforms fix everything.” Most services re-encode uploads, and odd rates or variable frame rate files are the ones most likely to stutter or lose sync.

Before you shoot or export

• Decide the delivery frame rate first, then shoot at it or at a whole multiple for slow motion.
• Set shutter speed with the 180° rule, and adjust for lighting flicker.
• Keep every clip in a project at one rate, or convert deliberately.
• Check that your bitrate matches the frame rate, using the resolution and bitrate guide.