# What is FK and IK in animation?

> FK (forward kinematics) and IK (inverse kinematics) are two ways to pose a rigged character. With FK you rotate each joint down the chain, shoulder then elbow then wrist, and the hand ends up wherever those rotations put it. With IK you move the hand or foot directly and the software calculates the joint rotations. FK gives natural arcs; IK keeps hands and feet exactly where you put them.

Updated November 2026. Source: https://www.exodeui.com/questions/what-is-fk-and-ik-in-animation/

## Key takeaways

- FK: rotate from the root outward; the end follows
- IK: place the end (hand, foot); the joints are solved for you
- FK is best for swings, arcs and overlapping motion
- IK is best for planted feet and hands holding or pushing things
- Most 2D rigging tools support both: Moho, Spine Professional, Harmony, Rive, Blender

## Frequently asked questions

### What does FK stand for in animation?

Forward kinematics: posing a chain by rotating each joint from the root outward.

### What does IK stand for in animation?

Inverse kinematics: posing a chain by moving its end point and letting the software solve the joint rotations.

### Is IK better than FK?

Neither is better. IK is easier for contact (feet, hands on objects); FK gives better arcs and overlap.

### Do 2D animation programs have IK?

Many do: Moho, Spine Professional, Toon Boom Harmony Premium, Rive, ExodeUI, OpenToonz, Blender and After Effects with Duik.

## Related

- [FK vs IK: when to use each](https://www.exodeui.com/questions/fk-vs-ik-when-to-use-each)
- [Best 2D rigging software with IK and FK](https://www.exodeui.com/best-2d-rigging-software-ik-fk)
- [How to rig a 2D character with IK](https://www.exodeui.com/questions/how-to-rig-a-2d-character-with-ik)
- [What is IK/FK switching?](https://www.exodeui.com/questions/what-is-ik-fk-switching)