QR Code Sticker Size: The Circle Costs You 30%

A Square Does Not Fit Inside a Circle

Almost every answer to this question is a list of diameters. That is the wrong shape of answer, because a diameter is not a canvas.

The largest square that fits inside a circle has a diagonal equal to the circle's diameter. Work that back and the square's side is the diameter divided by the square root of two, which is about 70.7% of it. So a 50mm round sticker offers a 35mm square, a 25mm dot offers about 17.7mm, and a 75mm sticker offers about 53mm.

Then the printer takes their bleed off. Die-cut stickers drift by a millimetre or two against the artwork, so anything you want to survive has to sit inside that. Take 1.5mm off each edge and the 50mm round sticker is a 32.4mm canvas.

This is the whole reason so many sticker codes come back broken. The designer sizes the code to the sticker, the die cut lands a millimetre off centre, and the first thing it eats is the quiet zone, which is the blank margin the scanner uses to find the symbol. The code looks complete and reads as nothing. We measured that failure mode separately in why a QR code will not scan.

Every Common Sticker Size, Measured

Here is every common sticker size against three real links, with the usable square worked out and the minimum width measured by this site's encoder.

Two things fall out of it. The last row is the argument for square stickers: same nominal size, same price bracket, and about 40% more usable area, because none of it is lost to the corners. If the code is the reason the sticker exists, a square sticker is simply a better buy.

And the difference between the first and last columns is larger than the difference between two sticker sizes. Which link you encode moves the minimum width more than going up a size does, which is the next section.

Shorten the Link Before You Shrink the Code

Module count follows character count, and the minimum printed width follows module count. So the cheapest way to make a code fit a small sticker is not to shrink it. It is to put less in it.

A full listing URL with a category and a product slug can be three or four times the length of a short address on your own domain, and the symbol grows through versions to carry it. Shortening the link costs nothing and buys real millimetres, which is the only change that makes a code smaller without making it harder to read.

Use an address you control rather than a public shortener. A branded short link encodes just as small and does not put a third party between your sticker and its destination, which is the failure described in why free QR codes stop working.

Getting It Through the Printer Intact

Five things worth doing before you order a run.

• Design to the usable square, not the sticker. Set your artboard to the usable width from the table, centre the code in it, and let the sticker be whatever size it is. Working the other way round is what puts the quiet zone in the die cut.
• Keep the quiet zone inside the sticker. The blank margin is part of the code, and on a sticker it has to be part of the sticker. A code whose margin ends at the edge is relying on whatever surface it is stuck to being plain and light.
• Raise error correction for anything that gets handled. Quartile rebuilds about a quarter of the symbol, which is the right level for a sticker that will be peeled, pressed with a thumb and rained on. High costs more modules and therefore a larger minimum size.
• Print one sheet before you order a thousand. Scan the real sticker, on the real material, under the light it will live in. Vinyl, laminate and a curved surface all take margin off, and none of them show up in the artwork.
• Avoid curved surfaces at small sizes. A sticker wrapped around a bottle or a cable distorts the module grid. If it has to curve, go up a size so the distortion is a smaller share of each module.

On finish, matt beats gloss outdoors. Glare across a glossy laminate washes out the contrast a scanner needs, and it is a more common cause of outdoor failure than dirt is. If the sticker is going somewhere bright, the contrast measurement is worth leaving more headroom on than you would for paper.

Fabric is harder still, because the weave distorts the module grid in a way vinyl does not. Putting a QR code on a shirt measures that case separately.

Which Numbers Are Measured and Which Are Arithmetic

Measured: every module count and minimum width in the table comes from this site's encoder at build time, at error-correction level Q and the 0.4mm per module this site uses throughout, and every payload was decoded back before its column was published.

Arithmetic: the usable square is the diameter divided by the square root of two, and the bleed allowance is a conservative 1.5mm per edge. Printers differ, so ask yours for their figure rather than trusting ours.

Not measured: what your printer, material and laminate do to a 0.4mm module. Nothing on this page can tell you that. Print one sheet, scan the real sticker under the light it will live in, and believe that over any table, including this one. The companion piece, minimum QR code size for printing, works through the same arithmetic for flat paper.