Image Splitter

The seamless Instagram carousel — where one panoramic image scrolls across several slides, each ending exactly where the next begins — and the 3x3 profile takeover that only resolves into a mosaic when someone visits your page both rest on the same operation: cutting one image into a precise grid of numbered tiles. The Image Splitter does that, and it does the arithmetic that usually goes wrong afterwards. Load up to twelve images at once (drag them in, browse, or paste from the clipboard) and the same grid runs over all of them.

There are three ways to describe the cuts. Columns and rows is the familiar one, up to 32 of each. Fixed tile size lets you name a pixel size instead — 512 by 512, say — and the number of tiles follows from the image. Custom cuts drop individual lines you drag around on the preview, for a split that is deliberately uneven: a wide hero strip above three narrower panels. Cut positions in that mode are stored as percentages, so the same arrangement transfers to every image in the batch regardless of its dimensions.

Whether the pieces fit back together depends on how the leftover pixels are handled, which is a setting rather than an accident. Use every pixel spreads the remainder one pixel at a time across the leading tiles, so tile sizes differ by at most a pixel and the set reassembles into the original with nothing missing. Crop remainder keeps every tile pixel-identical and discards the leftover strip, taken evenly off all four edges or off the right and bottom only. Pad remainder also keeps tiles identical but fills the short edge tiles out to full size with your chosen background colour, which is what a game engine expects from a frame set.

The preview is where the tool earns its keep. Every cell carries the number it will actually be exported as, the region no tile consumes is shaded out, and clicking any cell drops it from the export while the rest renumber to close the gap. Because an Instagram profile grid fills right to left and bottom to top, the numbering order is one of five choices rather than something you work out by hand — pick the reverse row order and the files come out named in the sequence you post them. Slicing runs on a canvas in your browser and nothing is uploaded.

A 1000-pixel width divided by three tiles is the whole problem in miniature: 333.33 pixels per tile does not exist. Most splitters quietly floor the division to 333 and throw the last pixel away, which is why reassembled tiles so often come up a hair short. Here the default spreads the remainder instead — the first tile takes 334 pixels, the other two take 333 — so every source pixel ends up in exactly one tile and none in two.

That guarantee is what makes a seamless swipe post work: the right edge of one tile is the pixel immediately left of the next tile's first column, with nothing dropped in between. If you would rather have tiles of genuinely identical dimensions, switch to Crop remainder and choose whether the sacrificed strip comes evenly off all four edges or only off the right and bottom.

The overlap slider works in the other direction. Turned positive, neighbouring tiles share pixels along every inner edge — the bleed a poster printed across several sheets needs so the seams can be trimmed without a white line appearing. Turned negative it removes pixels at each seam instead, leaving a visible gutter when the tiles are laid out side by side. It is clamped to half the smallest tile, so it can never eat a tile whole.

The profile grid is the best-known use and the one with the awkward convention. Instagram fills a grid right to left and bottom to top, so reading-order numbering means posting the last file first. Choosing the Instagram grid preset applies square tiles, a 1080 by 1080 output and the reverse row numbering together, after which the tiles are simply posted in order. A note appears if the tiles fall outside the 4:5 to 1.91:1 range the platform accepts, since anything outside it gets re-cropped on upload and the seam breaks.

Away from social media the same geometry serves other work. Sprite sheets come apart into individual frames, best exported as transparent PNG with zero-based numbering. A poster too large for one sheet of paper is tiled with a bleed overlap. Map and texture tiles want a fixed pixel size with the short edges padded rather than left small. A scanned page holding several receipts is better handled with custom cuts than a uniform grid.

Two things worth knowing before you start. Plan the framing first: a grid laid over a portrait with a cut line down the subject's face is technically correct and visually ruined, and the preview exists so you see that before you download anything. And splitting is not compression — nine tiles come to roughly the size of the original, so this multiplies your file count without reducing total bytes.