Getting the grid right
A sprite sheet only animates cleanly when every cell is the same size. Divide the sheet’s width by the number of columns and its height by the number of rows — the tool shows the resulting frame size. If the overlay lines cut through your characters, the column or row count is off; if the sheet has a margin or uneven spacing, crop it to the grid first.
Frames are read row by row. If your sheet stores animations in columns instead, rotate it 90° first, or rearrange it. The reverse direction is just as easy: GIF to Sprite Sheet packs any GIF into a sheet plus JSON frame data for game engines.
Pixel art without blur
Pixel art looks best at its native size or at whole-number multiples. Keep the output width equal to the frame width, then enlarge the finished GIF with Resize GIF at 200% or 400% if you need it bigger. Typical sprite animations run at 8–12 fps, which matches the hand-animated feel of most games.