What is Slow in Slow out animation? Guide For Beginners.

Animation can be a very fun and rewarding process, but it can also be confusing and difficult to understand at first. This guide is 6th Princple out of 12 Principle of Animation designed to help beginners get started with animation and understand the basics of Slow in Slow out animation.

What is Slow in Slow out in animation?

This principle refers to the way pretty much all movement starts slowly, builds speed, and finishes slowly. Without Slow In and Slow Out, things feel mechanical. That’s because robots are one of the only things that actually move their parts at a constant speed. This is called also easing in and easing out. In this article, we’ll look at what easing is and how you can use it to improve your animations.

slow in slow out examples car
Credits – Alan Becker

In animation, Slow in and Slow out are terms used to describe the speed of movement at the beginning and end of an animation. Slow in means that the object starts moving slowly and speeds up as it approaches the end.

Slow out means that the object starts moving quickly and slows down as it approaches the end. The purpose of using these techniques is to make the animation look more natural.

What is the difference between Slow In & Slow Out in animation?

Easing is the process of making an object’s movement appear more natural by adding subtle curves and changes to its path. This makes the object’s movement seem more fluid and realistic.

Animation is considered to be “Slow in” if the movement of objects starts slowly and gradually becomes faster. This technique is often used to create a feeling of weight or mass. Slow in animation can also be used to make an object or character seem more threatening.

slow in slow out examples

“Slow out” animation refers to the opposite technique, in which objects start quickly and then slow down. This gives the appearance of fluidity and speed. Slow out animation is commonly used for actions that need to feel light and effortless, such as a character running or jumping.

Why is slow in and slow out important for animation?

When animating, it’s important to make sure that the “in” and “out” of each movement are smooth. This means taking the time to plan out each frame and ensuring that there isn’t a sudden change in direction or speed. When an animation doesn’t flow smoothly, it can be very jarring for the viewer.

Slow in and slow out is important for animation because it helps to create a sense of weight and motion. When objects move slowly in and then quickly speed up or slow down, it can be jarring for the viewer. By animating objects with a slower in and out, you create a more fluid and natural movement that is less likely to cause confusion or discomfort.

slow in slow out difference

One of the reasons why slow in and slow out is so important is because it gives the illusion of realism. If an object suddenly speeds up or changes direction, it will look fake and robotic. By making sure that all movements are gradual, we can create animations that look more realistic.

Another reason why this principle is important is that it helps to create a sense of weight and fluidity. When objects move quickly and without warning, they can feel lightweight and unrealistic.

Timing And Spacing

Animation is all about timing and spacing. Getting the timing and spacing just right can make or break an animation. If the timing is off, the animation will look choppy and floaty. If the spacing is off, the animation will look cluttered and chaotic.

slow in slow out timing and spacing

Good timing and spacing take practice to get right. It’s something that you’ll continue to refine as you become more experienced with animation. There are no hard-and-fast rules when it comes to timing and spacing, but here are a few tips to help you get started:

Tip: Patience And Practice

Slow In Slow Out Animation Examples

When animators want to create the illusion of realistic motion, they often use the principle of slow in slow out. This means that they animate objects starting slowly and then speeding up as they move. This gives objects a more lifelike appearance and makes them less jarring to watch. There are many examples of slow in slow out animation but for now, we will go through a few examples for references.

So let’s Start

Example 1

As you can observe the head is moving from left to right and there is less spacing and more keys/Poses in the beginning which shows that the head is slowing in . And then you can see at the end the head is slowing out because there is less spacing and more keys/poses.

If we don’t apply this principle to our animation, our character will look robotic and jumpy. But animation professionals want to see their characters filled with emotion and robots are emotionless.

slow in slow out examples car
Credits – Alan Becker

Example 2

So here there comes the pendulum, waving and you can see it’s slowing in and slowing out. Whenever it reaches the Highest point. As you can see there are less spacing and more keys/Poses while it is slowing in and slowing out.

This is a Basic example of Slowing in and slowing out to give you rough idea about what this principle is about.

slow in slow out pendulum


In conclusion, slow in slow out animation is an efficient way to create movement in a scene and give the illusion of life. By understanding the basics of this animation technique, you can create more believable and compelling animations.

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