Frame Rates: 24, 30, 60 and What Happens When You Mix Them

Frame rate gets treated as a quality dial, with higher numbers assumed to be better. It is not one. It is a decision about how finely motion is sampled and how much blur ends up in each frame — and those two things produce the difference between footage that reads as film and footage that reads as a live broadcast.

Getting it wrong produces two distinct problems. The look is not what you expected, or the timeline judders because two rates are fighting. This guide covers what each rate is actually for, the shutter relationship that matters more than the rate itself, what happens when you mix, and how to handle slow motion without generating frames that were never captured.

What the Numbers Do

The fractional rates deserve a note. 23.976 and 29.97 exist for historical reasons in colour television and remain in wide use. They are close enough to their round numbers to look identical and different enough to drift out of sync over long durations, which is why mixing 23.976 and 24 in one project causes problems that are invisible for the first minute.

Shutter Does the Look

The property people are chasing when they say a frame rate looks cinematic is usually motion blur, and blur is set by the shutter rather than by the rate.

The working convention is a shutter of roughly double the frame rate: 1/48 of a second at 24 frames, 1/60 at 30, 1/120 at 60. That produces an amount of blur per frame that viewers have been trained by a century of film to read as natural.

Depart from it deliberately and you get two recognisable effects. A much faster shutter — 1/500 at 24 frames — freezes each frame sharply, and the sequence reads as staccato and slightly unreal. A much slower shutter smears movement into trails.

The practical consequence is a lighting problem. Holding a shutter near the convention means you cannot use it to control exposure, so bright conditions require neutral density filters rather than a faster shutter. That is the single most common reason outdoor footage ends up looking harsh and video-like without the shooter knowing why.

Mixing Rates

A project containing more than one frame rate is common and only sometimes a problem. What matters is whether the conversion divides evenly.

Even division works. 60 into 30 drops every second frame cleanly. 30 into 60 doubles each frame. Neither introduces uneven timing, so the result looks correct even though it is mechanically crude.

Uneven division judders. 24 into 30 is the classic case. Six extra frames per second have to come from somewhere, so some frames are held longer than others, producing a repeating stutter. It is nearly invisible on static shots and obvious on a slow pan, which is exactly where an editor is least likely to test it.

Fractional mismatches drift. 23.976 against 24, or 29.97 against 30, look fine and gradually lose sync with audio across a long timeline. This is the one that gets discovered at the end.

There are two honest fixes. Set the timeline to the rate of your primary footage and accept the conversion on the minority material, ideally hiding it in shots without slow movement. Or conform the odd footage properly with a retiming tool that generates intermediate frames — which works well on simple motion and produces visible artefacts around edges and fast action.

Slow Motion Is Captured, Not Created

Slowing footage down means showing more frames than were recorded for that span of time, and there are only two ways to supply them.

Capture them in the first place. Shoot at 60 and conform to 24 and you get a smooth, genuine slow-motion result with real detail in every frame. This is why the high rates exist, and why the decision has to be made at the shoot rather than in the edit.

Or generate them. Modern retiming can invent intermediate frames convincingly for simple, predictable movement. It struggles with occlusion — anything passing in front of anything else — and with fast limb movement, where it produces the distinctive melting artefacts around edges.

There is a lighting cost to shooting high that catches people out. Holding the shutter convention at 60 frames means 1/120 of a second, which is half the light of 1/60. High-speed capture in a dim room is a trade between motion sampling and noise, and noise then costs you bitrate at export as well, for the reasons in how bitrate, resolution and quality relate.

Frame Rate in the Edit

Two places where the rate stops being a shooting decision and becomes an editing one.

Action cuts depend on matching speed. A gesture crossing a cut has to continue at the same rate on both sides, and footage from two cameras at different frame rates will not do that unless it has been conformed first. The cut then reads as a hesitation, and the cause is easy to miss because the join itself is correct — the requirements are set out in cutting on action and the joins that need matched motion.

Higher rates change perceived pace. Sixty-frame footage feels faster than the same action at 24 because more of the movement is resolved. A sequence that felt correctly paced in one rate may need different shot lengths in the other, which interacts with the wider question of pacing across a piece.

What Frame Rate Costs at Export

Higher rates are not free downstream. Every additional frame per second is another picture the encoder has to describe out of the same allowance, so a video delivered at sixty frames gets roughly half the data per frame that the same file at thirty would.

On content with genuine fast movement that is a good trade — the extra temporal detail is what you are paying for. On a talking head it is a straight loss, spending the budget on near-duplicate frames while the encoder has less left for the parts that actually change.

The practical version is to let the content decide and then be consistent. If you are shooting interviews at sixty out of habit, dropping to thirty gives every remaining frame twice the bits at the same file size, which is a visible improvement for no effort.

Choosing and Sticking To It

Decide before the shoot, not at import. Pick the rate that suits the material — filmic and considered, or immediate and live — and use it for every camera on the production, including phones and screen recordings, which default to whatever they feel like.

Set the timeline to match the footage rather than converting on import. Export at the rate you shot at; raising it at export duplicates frames and adds file size for no benefit, and lowering it discards motion you paid to capture. The delivery side of that sits with the rest of the specifications in export settings for each major platform.

Where a project genuinely has to mix, decide which rate is the master early, and conform everything else on the way in so the timeline holds one rate throughout. Fixing cadence at the end, across a finished edit, is the version of this problem that costs a day.

Next Steps

Check what frame rate your last three projects were actually shot at, including any phone footage and screen recordings in them. Mixed rates within one project are common and usually unintentional, and finding one explains a lot of vague dissatisfaction with how the edit moved.

Then set your camera's shutter to roughly double whatever rate you shoot at and leave it there, controlling exposure with aperture, ISO and filters instead. That one habit does more for how footage reads than any change of frame rate. The rest of the technical material is under formats, specs and delivery.