# QR codes

> The QR element, error correction levels, size and length.

Source: https://82label.app/en/docs/qr/

A QR code is a square element. `size` is its side in mm; without a position it goes in the middle. Use it for long values such as order lookup URLs, product pages or stock location codes.

```js
{ type: 'qr', x: 36, y: 4, size: 20, value: 'https://shop.example.com/o/{{orderNo}}', ecc: 'M' }
```

```js
const template = {
  v: 1,
  name: 'Stock location',
  paper: { kind: 'roll', dpi: 203 },
  label: { width: 60, height: 30 },
  elements: [
    { type: 'qr', x: 3, y: 3, size: 24, value: 'LOC:{{loc}}', ecc: 'Q' },
    { type: 'text', x: 30, y: 5, w: 28, h: 10, text: '{{loc}}', size: 16, bold: true, fit: 'shrink' },
    { type: 'text', x: 30, y: 16, w: 28, h: 10, text: '{{desc}}', size: 8, fit: 'wrap' },
  ],
};

const rows = [{ loc: 'A-03-12', desc: 'Floor 2, zone A, shelf 3, bin 12' }];

Label82.print(template, rows);
```

## Error correction (ecc)

| ecc | Recovers | Use |
| --- | --- | --- |
| `L` | about 7% | Clean indoor labels, long values |
| `M` | about 15% | The default |
| `Q` | about 25% | Warehouses, labels that get scratched |
| `H` | about 30% | Dirty environments |

## Size and length

- Modules of 0.25 mm or more read well with phones. Longer values need more modules, so raise `size`.
- The quiet zone (two modules) is included.
- A value that is too long raises `QrError` (`qr_too_long`) and draws a crossed box. Shorten URLs.

```js
Label82.qrSVG('https://82label.app', { size: 30, ecc: 'M' }); // just the QR picture
```