Sprite Animation Previewer

Upload a sprite sheet and preview the animation with adjustable frame size, speed, and playback controls.

Tested tool guide Tested browser tools Checked August 16, 2026

What Sprite Animation Previewer does, with a checked example

A sprite sheet packs several animation frames into one image, and this tool plays them back for you without any game code. You upload the image, enter the pixel size of a single frame, and the preview crops and cycles through the cells in row order at a speed you set, with play, pause, and step controls. The mistake most people make first is the frame size: the crop only lines up when the width and height you enter match the sheet's grid exactly, so a wrong number shows as a sliding, bleeding animation rather than an error. The image never leaves your browser.

Worked example

A concrete input and expected output from the current implementation.

Input

walk.png, a 256 x 64 image holding four 64 x 64 frames in a row. Enter frame width 64, frame height 64, speed 8 fps.

Expected output

The preview crops and plays the cells at (0,0), (64,0), (128,0) and (192,0) in order, looping. Each frame shows for 0.125 s and the 4-frame cycle repeats every 0.5 s. Pausing lands on exactly one 64 x 64 cell with no bleed from its neighbors.

256 / 64 gives 4 columns and 64 / 64 gives 1 row, so 4 frames total. At 8 fps each frame lasts 1/8 s (0.125 s), and 4 frames x 0.125 s = 0.5 s per loop.

How the result is produced

Grid slicing

Frame indexing comes from the numbers you enter: the sheet is divided into columns by frame width and rows by frame height, and each frame occupies the cell at (column x frameWidth, row x frameHeight). Frames play left to right, top to bottom, so the total count is columns x rows. If either dimension does not divide the sheet cleanly, the crop windows straddle cells and the preview visibly misaligns.

Playback timing

The speed control sets frames per second: each frame stays on screen for 1 divided by the speed, and the cycle wraps from the last frame back to the first, so one loop takes frame count divided by speed seconds. Play and pause start and stop the timer, and stepping moves one frame at a time, which is how you inspect each crop while the animation is frozen.

Good uses

Check a sprite sheet you just exported from a game art tool before wiring it into your engine, so misaligned crops and wrong frame order surface here instead of in the game.
Decide a playback rate for an animation: run the same loop at a few speeds and settle on the frames per second that makes a walk cycle or attack animation read naturally.
Work out the grid of a sprite sheet from an asset pack that shipped without metadata: try frame sizes until the preview freezes on clean single cells, which reveals the real cell size and frame count.

Limits and checks

Frame width and height must be exact. Even a one-pixel error makes crops bleed across cells and the animation appear to slide; the grid is taken from the numbers you type, never guessed from image content.
Order is assumed row-major (left to right, then top to bottom). A sheet packed column-first, or whose frames were reordered by a packer, plays in a scrambled sequence; watch the first few frames closely, not just the loop.
A JPEG sheet previews fine but cannot carry transparency: the background color is baked into every pixel, so what looks clean in the preview will show its old background when composited in a game. Export with a PNG to keep alpha.

Common questions

The animation slides sideways instead of switching frames. What did I do wrong?

The frame size you entered does not match the sheet's real grid, so each crop window straddles two cells and the picture drifts with every tick. Re-open the sheet in the tool that exported it, read the exact cell size (and any padding or margin between cells), and enter those numbers. When they are right, pausing freezes a single clean frame.

I set 8 fps here, but the animation looks much faster in my game. Is the preview wrong?

No. The preview plays the sheet at the rate you set: exactly 8 frames per second, per loop. Most games render at 60 fps or more and advance sprite animation on their own timer, so the same sheet can run faster or slower in the engine. Use the preview to validate the frames themselves, and set the final pacing in your game.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.