An animation “on ones” is composed of 24 unique drawings for every single second of screen time. Each individual frame contains a different image, with no drawing repeated or held across multiple frames. This makes it the smoothest and most labor-intensive form of traditional animation possible at the standard cinematic frame rate.
How Frame Rate Creates the Baseline
The film and animation industry standardized on 24 frames per second (fps) decades ago, largely because the arrival of sound in movies required a fixed, consistent playback speed. That 24 fps rate remains the standard today across movies, streaming video, and most professional animation. Every second you watch on screen is built from 24 individual slots, and “on ones” means filling every single one of those slots with a brand new drawing.
This is where the terminology gets its name. “Ones” refers to how long each drawing stays on screen: exactly one frame. Compare that to animating “on twos,” where each drawing is held for two frames, cutting the total to 12 unique drawings per second. Animating “on threes” holds each drawing for three frames, requiring only 8 drawings per second. The higher you go, the choppier the motion becomes, but the less work each second demands.
What Makes On Ones So Smooth
Because every frame is different from the one before it, animation on ones produces the most fluid motion possible in hand-drawn work. The eye perceives continuous, lifelike movement with no visible “stepping” between poses. This is especially noticeable during fast action sequences, sweeping camera moves, or scenes with complex overlapping motion where holding a drawing for even two frames would make the movement look slightly jerky.
A famous example of full ones animation is Richard Williams’ film The Thief and the Cobbler, which spent roughly 30 years in production. Williams and his team painstakingly painted every single frame by hand at 24 fps. The result was a hypnotic, almost surreal fluidity that kept viewers’ attention in a way that lower frame rates simply couldn’t match. The high frame rate combined with the film’s abstract visual style created imagery that felt alive in a way few animated films have replicated.
Why Most Animation Doesn’t Use Ones
The math tells the story. A single minute of animation on ones requires 1,440 unique drawings. A 90-minute feature film animated entirely on ones would need nearly 130,000 individual illustrations. That’s an enormous amount of labor, and it’s the main reason professional animators developed the shortcut of holding frames.
Animating on twos, with 12 drawings per second, cuts the workload in half while still producing motion that looks smooth to most viewers. For slower, more deliberate movements, twos are often indistinguishable from ones. Threes work for even slower actions or stylistic choices, though the reduced frame count starts to become visible as a more staccato rhythm.
Mixing Ones and Twos in Practice
Most professional animation doesn’t commit to ones or twos for an entire production. Instead, animators switch between them within the same scene based on what the action demands. A character standing still and talking might be animated on twos or even threes, since there’s little fast movement to capture. The moment that character throws a punch or catches a ball, the animator shifts to ones so the rapid motion reads clearly and feels impactful.
This mixing can happen at a granular level. In some sequences, different elements within the same frame are on different timing. A character’s body might move on twos while a fast-moving object they’re interacting with switches to ones at the exact moment of contact. Skilled animators use these transitions strategically so the shifts in frame rate are invisible to the audience but create subtle emphasis on the fastest, most dynamic parts of the action. The goal is to use ones where they actually improve the motion, rather than forcing every drawing onto ones when twos would look just as good.
On Ones in Digital Animation
In digital animation software, the concept works the same way but the workflow looks different. Instead of physical drawings on paper, animators work with a timeline or exposure sheet that controls how long each drawing stays on screen. The “exposure” of a drawing is the number of frames it occupies. Setting every drawing to an exposure of one frame is the digital equivalent of animating on ones.
3D computer-generated animation typically renders at 24 fps by default, with the software generating a unique image for every frame. This means most CG animation is technically “on ones” without the animator having to manually create each in-between image. The computer handles the interpolation. Hand-drawn digital animation, however, still requires the same manual effort as traditional paper animation, and the choice between ones, twos, and threes remains a deliberate creative and practical decision for every scene.