Why decide the sprite size first
Pixel art is hard to resize after you draw it. If you mix art with different pixel sizes, or scale it by a factor that is not a whole number, pixel widths become uneven and the crisp pixel art look breaks down.
Sprite size also affects camera settings such as PPU and Reference Resolution, how many tiles fit on screen, and how much work you need to do. If you change it after you have started drawing, you may have to redraw all of your assets. That is why it is best to decide early in the project.
What is sprite size?
Sprite size is the width and height of a sprite (an image displayed in the game) in pixels. “32x32” means an image that is 32 pixels wide and 32 pixels high.
In Unity, the size a sprite takes up in the world (the space inside the game) is determined by this formula:
Size in the world (units) = Sprite size in pixels ÷ Sprite’s PPU
For example, if you import a 32 x 32 pixel sprite with a PPU of 32, it becomes 1 x 1 units. For what PPU means, see What Is Unity’s Pixel Perfect Camera? PPU and Reference Resolution Explained.
Common sizes and their characteristics
Numbers such as 16, 32, and 64 are common in pixel art. They usually refer to the size of one basic tile or a rough size for characters.
| Size | Characteristics | Suited to |
|---|---|---|
| 16x16 | Few pixels per image, so less work to draw. The look is simple and easily gives a retro feel. | Tiles, small characters, items |
| 32x32 | Lets you draw some detail and expression. Easy to balance effort and expressiveness. | Characters, tiles, UI |
| 64x64 | Lets you draw fine patterns and shading. More work to draw, and the workload grows quickly as animation frames increase. | Larger characters, enemies, background parts |
A character does not have to be square. For example, in a game with 16 x 16 tiles, it is common to make a humanoid character 16 x 32: one tile wide and two tiles high.
Sprite sizes also do not have to be powers of two (16, 32, 64, and so on). However, unless the Non-Power of 2 setting in Unity’s import settings is set to None, the size may change at import. For details, see Why Pixel Art Looks Blurry in Unity and How to Fix It.
Three points to consider when choosing a size
1. How much detail do you want to draw?
The larger the size, the finer the detail you can express. At the same time, there are more pixels per image, so there is more to draw. When you add animations such as walking, running, and attacking, the work adds up with every frame you need.
If you are working alone, it is realistic to put priority on a size you can finish drawing. When in doubt, starting small makes it easier to reach the finish.
2. How many tiles do you want on screen?
The visible area is Reference Resolution ÷ tile size. With the same Reference Resolution, larger tiles mean fewer tiles on screen.
| Reference Resolution | 16 px tiles | 32 px tiles |
|---|---|---|
| 256 x 144 | 16 x 9 tiles | 8 x 4.5 tiles |
| 320 x 180 | 20 x 11.25 tiles | 10 x 5.625 tiles |
| 480 x 270 | 30 x 16.875 tiles | 15 x 8.4375 tiles |
| 640 x 360 | 40 x 22.5 tiles | 20 x 11.25 tiles |
If the tile count does not divide evenly, a tile is simply cut off at the screen edge, and nothing breaks. If you want the tiles to fit neatly, though, use the Reference Resolution width divided by the tile count as the tile size. For 16:9, dividing the width by 16 gives exactly 16 x 9 tiles on screen.
| Tile size | Reference Resolution (fits 16 x 9 tiles) |
|---|---|
| 16 px | 256 x 144 |
| 24 px | 384 x 216 |
| 32 px | 512 x 288 |
| 40 px | 640 x 360 |
If you want to fill a 16:9 screen by a whole-number factor, Reference Resolutions that divide 1920 x 1080 evenly (such as 320 x 180, 480 x 270, 640 x 360, and 960 x 540) are convenient. Only a limited set of values satisfies both “tiles fit neatly” and “fills the monitor by a whole-number factor,” so decide which one to prioritize.
3. Use even sizes
Make the width and height of a sprite even numbers whenever you can. With an odd size, when the pivot is at the center, the edges of the sprite sit half a pixel off the pixel grid. That can make pixel widths look uneven or positions look blurry.
Also, if the size is a multiple of the PPU, the sprite’s size in the world is an exact whole number of units, which makes it easier to align with tiles (1 unit).
The order in which to decide
- Decide the tile size: Choose a basic size such as 16 px or 32 px, based on how much you can draw and how detailed you want it to be.
- Decide the PPU: Match it to the basic tile size. A PPU of 16 for 16 px tiles, or 32 for 32 px tiles, is common. Use the same PPU for your sprites as for the camera.
- Decide the size of characters and other sprites: Use the tile as the reference and decide how many tiles each one covers. Keep the width and height even.
- Decide the Reference Resolution: Choose it from the number of tiles you want on screen and the aspect ratio of the monitors you want to support.
- Check on screen: Place placeholder sprites and check how large they look, and what the scale is at each monitor resolution.
- Start drawing the final assets: Draw them once the sizes are settled.
Steps 4 and 5 are ones you will go back and forth on. Checking on screen before you draw the final art, even with plain rectangles, helps you avoid rework.
Common mistakes
| Mistake | What happens | What to do |
|---|---|---|
| Mixing pixel art of different sizes | Pixel size differs between assets and the look loses consistency. | Decide a basic tile size for the project and draw assets to that standard. |
| Scaling by a non-whole-number factor | Pixel widths become uneven. | Draw assets at the size you will actually use. Scale only by whole numbers. |
| Odd width or height | Edges sit half a pixel off. | Use even sizes. |
| Sprite PPU differs from the camera PPU | The on-screen size changes. If the scale is not a whole number, pixels are distorted. | Use the same PPU for the camera and the sprites. |
| Starting with a very large size | The amount of drawing balloons and the game never gets finished. | Start with a size you can finish, and increase it later if needed. |
| Making sprites larger than the Reference Resolution | They do not fit on screen. | Check how much of the screen each sprite takes up. |
Check with our tool
Our Pixel Perfect Camera Preview lets you enter PPU and Reference Resolution values and see how sprites look at their width and height, or with a different PPU for each sprite. It shows warnings when a sprite has an odd size, when its size is not a multiple of the PPU, or when it is larger than the Reference Resolution. You can also check the scale for each monitor resolution, so use it to experiment before you decide on a size. Your input and loaded images are never sent anywhere.
The guidelines in this article summarize general ways of thinking. The right size depends on your game and the look you want. Names and labels in Unity may differ between versions, so be sure to also check the manual for the version you use.