Flyer sizes guide: print and social, in mm and pixels

Ask three people what size a flyer is and you get three answers: A4, 1080 by 1080, and “whatever the printer wants”. They are all right, because a flyer size is really three numbers stacked on top of each other, and most arguments about sizing are two people quoting different ones at each other.

Paper size, canvas pixels, export pixels

The paper size is physical. A4 is 210 by 297 millimetres and always has been. This is the number your printer cares about, and the only one that means anything once the file is off a screen.

The canvas size is how many pixels the design is laid out on. This is a working number. It has to be large enough that text and images look right, and small enough that the editor stays responsive while you drag things around. Print canvases here are authored at 150 dots per inch, which puts A4 at 1240 by 1754.

The export size is what actually comes out of the file. The renderer captures each page at twice the canvas resolution, so an A4 flyer exports at 2480 by 3508. That is exactly 300 dots per inch at 210 by 297 mm, which is what a commercial printer asks for.

The reason to keep the three separate in your head is that they answer different questions. If a designer asks what size to work at, the answer is the canvas. If a printer asks what size the file is, the answer is the export. If a client asks how big the flyer is, the answer is A4.

Print sizes, and what printers expect

A4 is the default for a reason: it is the size a person expects to be handed, it fits a standard letterbox without folding, and every printer on earth has stock for it.

Below A4, the ISO series halves each time. A5 at 148 by 210 mm is A4 folded once, and is the usual letterbox drop because it costs less and still carries one offer. DL at 99 by 210 mm is a third of A4 down the long edge, which is the shape that fits a standard envelope and a leaflet rack. Neither is a canvas preset here, so design at A4 and let the printer scale, or set a custom size.

Outside Europe, US Letter at 216 by 279 mm is the equivalent default. It is slightly wider and slightly shorter than A4. The difference is small enough to look like nothing on screen and large enough to shift a footer off the page if you send an A4 file to a Letter press without checking.

One thing to be clear about: the export is the trim size with no bleed. There is no bleed area, no crop marks and no CMYK conversion in the file. If your printer’s template asks for 3 mm of bleed on each edge, the file needs that added in their template rather than assuming it is there. A background colour that runs to the edge of a trim-size file will show a white sliver if the guillotine drifts by half a millimetre, which it will.

Social sizes and their safe areas

Social sizes are screen sizes, so dots per inch does not apply. What matters instead is the shape and what each platform crops.

The square at 1080 by 1080 is the safest thing to make first. It survives almost every placement. The story and reel shape at 1080 by 1920 is full screen on a phone, and it is the one where safe areas bite: the top and bottom of that frame carry the platform’s own interface, so anything important belongs in the middle two thirds.

The wide sizes split into two jobs. Feed posts at 1200 by 630 and 1200 by 627 are per-campaign. Cover and header images at 820 by 312 and 1500 by 500 are set once and left alone, and both get cropped differently on a phone than on a desktop, so keep the subject central and away from the edges.

Every one of these exports at twice its canvas, so a square post leaves as 2160 by 2160. That is more pixels than any feed needs, and it means the file survives being re-compressed on upload with something left over.

Posters: A0 and the 36 by 48 inch equivalent

A0 is 841 by 1189 mm, which is sixteen A4 sheets. The canvas is authored at 50 dots per inch rather than 150, because a 300 DPI A0 canvas would be roughly 9933 by 14043 pixels and unusable in a browser. That gives a working canvas of 1656 by 2340, exporting at 3312 by 4680, which is about 100 dots per inch at final size.

For a poster that is the right trade. A conference board is read from a metre or more away, and the resolution the eye can actually resolve at that distance is far below what a hand-held flyer needs. Where it matters is placed photographs: an image that looks fine at 1656 pixels wide on screen is being printed most of a metre wide, and it will be soft. Check the images, not the canvas.

If you are printing in the United States, the common academic poster is 36 by 48 inches, which is 914 by 1219 mm. That is close to A0 but not the same, and the aspect ratios differ enough that a design laid out for one will not drop into the other without the margins changing.

Moving one design between sizes

This is where most of the wasted work happens. An A4 flyer is tall and narrow. A Facebook cover is short and wide. There is no crop of the first that is a good version of the second, because the layout was composed for a different frame.

Switching size re-runs the layout rather than stretching it, so text reflows into the new shape and blocks are repositioned for it. That is the difference between a resized design and a squashed one. Where the design is mostly a photograph with generous margins, a straight pixel refit works and there is a browser tool on this site that will do it for every canvas at once. Where the layout is dense, accept that the social versions are separate designs that share a look, not copies.

The practical order that saves the most time: design the print version first, because it is the most constrained, then let the social versions be built from it. Going the other way, from a square post up to A4, means inventing content to fill the space.