Can I make a sprite sheet from a single image?

Yes, three ways. If the image already contains a strip or grid of frames, slice it by grid. If it is one static character, an AI image model can generate a multi-pose frame grid from it. And if you only need one frame, a 1×1 sheet is a perfectly valid sprite sheet.

What size should sprite frames be?

Pick one size and keep every frame identical. 32×32, 64×64 and 128×128 are common defaults; pixel art usually stays at 16–64 px. Mismatched frame sizes break grid-based importers like GameMaker's, and make animation preview jittery.

Does a sprite sheet need a transparent background?

Almost always. PNG with alpha is the standard — the background of the game shows through everywhere the frame is transparent. Never flatten your art onto white; if you only have a flattened image, remove the background before packing.

How do I import the sheet into Unity or Godot?

Packed output may contain spacing and nonuniform frame positions. In Godot, create AtlasTexture regions from the JSON frame rectangles and add them to SpriteFrames; use Hframes/Vframes only for an original equal-cell grid with no gaps. Unity needs an atlas-aware importer or manual rectangle slicing for packed output. The Phaser playback example accepts the exported PNG and JSON together.

Is AI frame generation free?

Local packing and slicing are free. Optional AI generation sends the prompt and your Gemini API key directly to Google, which may require billing and charges for image generation. Entering a key does not save it automatically; Save stores it in this browser's localStorage and Forget removes it. Review Google's current API pricing before generating.

Image to Sprite Sheet — How to Turn One Image Into Game Frames (Free)

First: which situation are you in?

Your image already contains multiple frames — a filmstrip, a grid of poses, frames exported from Aseprite/Krita spaced evenly. → Route 1: slice it.
Your image is a single character and you need an animation — one idle pose, no frames. → Route 2: generate the missing frames.
Your image is a single sprite and that's fine — items, icons, a static bullet. → Route 3: pack it as a 1×1 sheet.

Route 1 — Slice a strip or grid you already have

This is the mechanical case, and it's free and instant:

Open the sprite sheet maker and switch to Slice sheet → frames.
Drop your image and set columns × rows (e.g. a 4-pose walk strip is 4×1).
The tool cuts exact frames — then it re-packs them with spacing and optional 1px extrusion, and you download the PNG + JSON atlas.

Check before slicing: frames must be evenly spaced. If poses are scattered (not on a grid), no automatic slicer can save you — cut the frames manually in any editor first, then pack them with the same tool's pack mode.

Flattened background? If the strip is on solid white instead of transparency, remove the background in your editor first (magic wand / color-to-alpha). Slicing preserves whatever pixels are there — including the white.

Route 2 — Generate the missing frames from one character

One static character can become a full frame set with an image model:

Open the AI sprite sheet generator.
Describe the character (or drop the same style/character into an image editor that supports image-to-image, then bring the result here).
Pick a grid — 3×3 is a good first try for a walk cycle — and generate.
The tool keys out the background, slices the grid, and packs a sheet. Judge it as a prototype: image models drift between frames, so generate a few times and keep the best result, or trace over it for production art.

The local tools are free. AI generation uses your own Gemini key and may require Google billing and available quota; check the current API pricing before generating. Prompts and keys go directly to Google; imported frame files are processed locally.

Honest limits: AI frame grids are strong for prototypes, jams and placeholders; frame-to-frame consistency is not guaranteed. If you need pixel-perfect animation, hand-drawn frames (Aseprite, Krita, LibreSprite) are still the reliable route — you can pack those in the maker afterwards.

Route 3 — Pack a single sprite

A sheet with one frame is still a sheet, and some pipelines want the atlas format regardless:

Open the maker (pack mode).
Drop your PNG — a 1×1 sheet is produced with correct atlas metadata.
Add more sprites later by dropping them in; the shelf packer grows the sheet and the JSON atlas stays consistent.

Engine import cheat sheet

Unity: import the PNG with Sprite Mode Multiple, then use an atlas JSON importer or slice its packed frame rectangles manually. Use grid slicing only when the source has equal cells with no gaps.
Godot 4: the packer defaults to 2px spacing and can place frames unevenly. Create an AtlasTexture per JSON frame rectangle, assign the PNG as its atlas and the rectangle as its region, then add those textures to SpriteFrames for AnimatedSprite2D. Hframes/Vframes applies only to an original equal-cell grid with no gaps.
Phaser 3: this.load.atlas('sprites', 'spritesheet.png', 'spritesheet.json'). Load your exported files in the playback example.
PixiJS: await Assets.load('spritesheet.json') — the JSON this site exports follows that format.
GameMaker: its grid importer needs equally sized cells in a regular grid. Use an atlas-aware workflow for shelf-packed output, or prepare a separate grid sheet; spacing and shelf positions remain even when extrusion is off.
Web CSS: the atlas JSON rectangles map 1:1 to background-position values.

Checklist before you ship the sheet

All frames the same size (or atlas metadata that says otherwise).
Transparent background — PNG with alpha, never flattened white.
Consistent frame order — animation order is the order in the atlas.
Spacing 2px+ and 1px extrusion if your engine uses linear filtering (stops color bleeding between frames).