QR Code Generator Widget

How it works

The widget encodes the text with the same QR library as the A2Z QR Code Generator page. Text is converted to UTF-8 bytes first, so accented letters, Indian scripts and emoji survive the trip to the phone; that is also why the byte count can be larger than the character count (é takes two bytes, ₹ three). Text made only of digits, or only of capitals, digits and a few symbols, is packed in the denser numeric or alphanumeric mode; everything else, including any lower-case link, uses byte mode. The encoder then picks the smallest of the 40 QR versions whose capacity at the chosen error-correction level holds the data. Capacity falls as correction rises: version 1 holds 17 bytes at L but only 7 at H, and the largest symbol, version 40 (177 x 177 modules), holds 2,953 bytes at L. Higher correction therefore makes a denser, larger code for the same link, in exchange for surviving scratches, dirt or a small logo sticker. The widget draws the code with the four-module quiet zone scanners expect, reports the byte count, version and module grid under the preview, warns about pale or inverted colours using the WCAG contrast ratio, and points out a bare domain such as example.com, which most phone cameras show as plain text rather than a link to open.

Method

• Encoding: ISO/IEC 18004 QR code, automatic version 1-40; mode numeric for digits only, alphanumeric for 0-9 A-Z space $ % * + - . / : only, otherwise byte mode with UTF-8 text
• Version = smallest v whose capacity in that mode at the chosen level holds the data; modules per side = 17 + 4v
• Byte-mode capacity (ISO/IEC 18004): v1 L17 M14 Q11 H7; v2 L32 M26 Q20 H14; v3 L53 M42 Q32 H24; v40 L2953
• Error correction: L restores about 7% of damaged codewords, M 15%, Q 25%, H 30%
• Quiet zone = 4 modules on every side
• Colour check: WCAG contrast ratio (L1 + 0.05) / (L2 + 0.05), shown to 1 decimal; warned below 4:1 or when the code is lighter than the background

Worked examples

Limitations

• Only static codes: the content is fixed inside the image, so there is no scan counting and a printed code cannot be redirected later.
• One mode is used for the whole text. Mixed content (for example a lower-case link followed by a long number) is not split into segments, and Kanji mode is never used, so some codes are a version larger than the minimum possible.
• The widget does not scan the result. Contrast, print size, quiet zone and the scanning app all affect readability, so test the printed code with a phone.
• Logos, rounded dots and other styling are not offered; they eat into error-correction capacity.
• Micro QR, rMQR and structured append (one message split over several codes) are not supported; input is capped at 2,953 characters, the byte-mode maximum of version 40-L.

Where publishers use it

• Restaurants and cafes letting staff make a table QR for the online menu without leaving the website
• Event organisers turning a registration link into a code for posters and slides
• Teachers and trainers sharing a worksheet or form link with a class
• Print shops and designers offering customers an SVG code that scales cleanly on banners

Questions

Sources

1. ISO/IEC 18004:2024 - QR code bar code symbology specification - ISO/IEC JTC 1/SC 31 . versions 1-40, byte-mode capacities, error-correction levels L/M/Q/H and the 4-module quiet zone (paid standard; edition 4, 2024)
2. Web Content Accessibility Guidelines (WCAG) 2.2 - contrast ratio - W3C . formula used for the colour warning; the 4:1 warning level is A2Z's own cautious threshold, not part of ISO/IEC 18004

Cite or recommend this tool

If you reference this tool in an article, course or documentation, these formats are ready to copy. They are optional - nothing is added to your site unless you paste it.

A2Z Tools QR Code Generator
https://a2z.tools/qrcode-generator

<a href="https://a2z.tools/qrcode-generator">A2Z Tools QR Code Generator</a>

[A2Z Tools QR Code Generator](https://a2z.tools/qrcode-generator)

QR Code Generator by A2Z Tools - https://a2z.tools/qrcode-generator