Make a QR code

How it works

A QR code is a grid of black and white squares that encodes text directly. There is no lookup and no database: a scanner reads the pattern and reconstructs the characters from the pattern alone. That is worth knowing because it decides what happens to your code in five years.

Static codes cannot expire

The code this page produces is static. Your link is inside the pattern, so it works for as long as the destination does, with nobody in the middle. Many free generators hand you a dynamic code instead, which encodes a short link on their server that redirects to your destination. That is genuinely useful when you need to change where a printed code points, and it is also a subscription: stop paying and the redirect stops resolving, and every poster you printed becomes a dead end.

The tradeoff is real rather than one-sided. A static code cannot be repointed after printing, and it carries no scan analytics. If you need either, a dynamic code is the right tool and this is not it.

What error correction buys

Every code carries redundant data so it still reads when part of it is dirty, creased or covered. Four levels exist: roughly 7, 15, 25 and 30 percent of the code can be destroyed and still recovered. The redundancy occupies modules, so raising the level either shrinks how much you can encode or pushes the code to a denser version.

Medium is the usual choice. Choose the highest level when a logo will sit over the middle, or when the code goes somewhere it will be handled, rained on, or printed on something that creases.

Size, and why it is integer scaled

The grid is drawn at a whole number of pixels per module, then the image is that many pixels across. A fractional module width lands rows on half pixels, and the soft edges that produces are a common reason a code photographs badly under a phone camera. The size you choose is therefore honoured to the nearest exact multiple, which is why the reported dimensions may sit slightly under the slider.

For print, the working rule is that the code should be about a tenth of the distance it will be scanned from. A code read at two metres wants roughly twenty centimetres. Contrast matters more than size: dark on light, never the reverse, and never a busy photograph behind it.

The quiet border

The specification requires four modules of blank margin on every side, and scanners use it to find where the code begins. It is included by default. Turning it off is for layouts that already leave clear space around the image, and a code pasted tight against text without it is the most common reason a scan fails for no visible reason.