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QR code error correction explained

QR codes ship with four levels of error correction (ECC) defined in ISO/IEC 18004: L (7%), M (15%), Q (25%), and H (30%). Each level reserves a percentage of the QR modules for redundancy, which lets the code remain scannable even when partly obscured or damaged. Higher correction means the code stays readable through more damage — and through a centred logo overlay — but produces a denser matrix.

  1. 1

    Level L — 7% recovery

    Smallest code at a given URL length, but cannot tolerate much damage. Use only when the code is printed on pristine surfaces and never overlaid.

  2. 2

    Level M — 15% recovery (default)

    Sensible default for most marketing codes. Good balance between code density and damage tolerance.

  3. 3

    Level Q — 25% recovery

    Recommended whenever a small logo (up to 15%) is overlaid in the centre, or when the code will sit on stickers exposed to wear.

  4. 4

    Level H — 30% recovery

    Required for logos covering 20–25% of the code area, or for outdoor signage exposed to rain, scratches, and fading. Densest matrix.

  5. 5

    Trade-off summary

    Higher correction = more redundancy = denser code = larger minimum print size for the same data. Pick the lowest level that meets your worst-case damage and overlay scenario.

Frequently asked questions

What is QRCode Suite?

QRCode Suite is a premium WordPress plugin that generates branded, dynamic QR codes directly inside your WordPress dashboard. Scan data is stored on your own server — not on a third-party SaaS platform — and WooCommerce orders can be attributed to specific QR codes.

Does QRCode Suite require a separate subscription?

The Free plan is available at no cost. Paid plans (Pro, Business, Agency) are licensed per WordPress site and billed monthly or annually. There is no separate per-scan fee.

What QR code types does QRCode Suite support?

QRCode Suite supports 15 QR code types: URL, vCard, Wi-Fi, SMS, Email, WhatsApp, PDF, Coupon, Plain Text, Social profile, WooCommerce Product, WooCommerce Reorder, Link Hub, Phone, and Dynamic URL.

Can I change the destination of a QR code after printing it?

Yes. Dynamic QR codes use a short redirect URL. You can update the destination from your WordPress dashboard at any time without generating or reprinting the code.

Is QRCode Suite GDPR-compliant?

Yes. QRCode Suite hashes IP addresses with SHA-256 before storage so no raw IPs are ever saved. It also filters bot traffic automatically and includes configurable data-retention settings.

Need help getting started?

Download the free plugin or browse all documentation.

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