# step_size var (movable atom)

Source: https://ref.dm-lang.org/atom/movable/var/step_size
Added in BYOND 490.

### Default value
> 32 (width of default icon; depends on world.icon_size)

This var defines how fast, in pixels, an atom will move by default. If you use lower values of `step_size` for most items in your world, you may want to consider raising `world.fps` (at higher performance cost).

When `Move()` is called by a step or walk, or by the built-in client movement verbs, a change of `step_size` is applied to `step_x` and/or `step_y`. Any movement within the speed of `step_size`, or up to one tile in distance (whichever is greater), is considered a slide and may partially succeed if an obstacle is bumped before reaching the final position.

### See also
- [step_x var (movable atom)](https://ref.dm-lang.org/atom/movable/var/step_x.md)
- [step_y var (movable atom)](https://ref.dm-lang.org/atom/movable/var/step_y.md)
- [Move proc (movable atom)](https://ref.dm-lang.org/atom/movable/proc/Move.md)
- [locs list var (movable atom)](https://ref.dm-lang.org/atom/movable/var/locs.md)
- [fps var (world)](https://ref.dm-lang.org/world/var/fps.md)
- [icon_size var (world)](https://ref.dm-lang.org/world/var/icon_size.md)
- [Gliding](https://ref.dm-lang.org/notes/gliding.md)
- [Pixel movement](https://ref.dm-lang.org/notes/pixel-movement.md)