Image splitter

What the grid does to odd numbers

Most images do not divide evenly. A 1000 px wide image cut into 3 columns wants 333.33 px per piece, and pixels do not come in thirds — so something has to absorb the remainder.

The obvious approach is to give every piece the same whole number of pixels and let the last one keep whatever is left. On 1000 ÷ 3 that is fine: 333, 333, 334. On 1000 ÷ 7 it is not — six pieces of 142 and a final one of 148, which is 4% wider than its neighbours and looks like a bug.

This page spreads the remainder instead, one pixel at a time across the leading pieces. The same 1000 ÷ 7 comes out as 143, 143, 143, 142, 143, 143, 143. No piece is ever more than one pixel different from any other, and the pieces always add back up to the original — nothing is cropped, and no row of pixels falls off the right-hand edge.

The status line tells you which case you are in. If the grid divides exactly, it says so; if it does not, it gives the range.

The pieces are named so they sort back together

Each file is named by its row and column — photo-r2c3.png is the third piece along on the second row down. The numbers are zero-padded to the width of the grid, so a 12-column split produces c01 through c12 rather than c1 through c12.

That matters more than it sounds. Unpadded numbering sorts c10 before c2 in every file manager and every programming language that sorts strings, which is exactly the moment a sliced sprite sheet turns into a jigsaw.

Format, and when it matters

PNG is the default and the right answer for anything with flat colour, sharp edges or transparency — screenshots, UI mockups, sprite sheets, diagrams. It is lossless, so a piece is exactly the pixels that were under it.

JPG is smaller for photographs, but it has no transparency: anything transparent is composited onto white before encoding. It also re-compresses, so each piece loses a little quality that it cannot get back.

WebP does both, and every current browser reads it.

What this is useful for

• Instagram and social grids — a 3×3 or 3×1 split of one image, posted as separate tiles that line up in the profile view.
• Sprite sheets — cutting a sheet back into individual frames.
• Large diagrams and maps for printing across several sheets of paper.
• Splitting a tall screenshot into pieces small enough to send.

Your image stays here

The picture is decoded, cut and zipped inside this page. Nothing is uploaded, and the archive is assembled in memory on your own machine.