Tạo Mã QR Văn Bản Miễn Phí

QR codes support four encoding modes, and the mode determines how efficiently your content is stored. Numeric mode is the most compact: it can fit up to 7,089 digits because it packs three digits into just 10 bits. Alphanumeric mode handles uppercase letters A-Z, digits 0-9, and nine symbols (space, $, %, *, +, -, ., /, :). It stores two characters in 11 bits and supports up to 4,296 characters.

Byte mode encodes each character as 8 bits using UTF-8, which covers every language and emoji but uses more space. Maximum capacity in byte mode is 2,953 bytes. The fourth mode, Kanji, handles Japanese characters specifically.

Most QR generators select the encoding mode automatically based on your input. If you type only numbers, you get numeric mode. If you include lowercase letters, the generator switches to byte mode, which roughly halves your capacity compared to alphanumeric. This is why a QR code containing the text 'HELLO WORLD' is visually simpler than one containing 'Hello World', even though the messages are nearly identical.

The maximum text length depends on which error correction level your generator uses. At Level L (7% error recovery), a Version 40 QR code holds up to 2,953 bytes. At Level M (15%), that drops to 2,331 bytes. Level Q (25%) allows 1,663 bytes, and Level H (30%) tops out at 1,273 bytes.

In practice, most generators create codes between Version 2 and Version 15, which means real-world limits are lower. A Version 5 code at Level M holds about 106 bytes, enough for a short paragraph of around 100 characters. A Version 10 code at Level M holds about 367 bytes.

If your text approaches 300 characters, the resulting QR code will be dense and may scan slowly on older phones. For reliable scanning in any environment, keep text QR codes under 250 characters. If you need more space, consider encoding a URL that points to your full content instead.

QR codes handle text in any language through UTF-8 encoding in byte mode. But character count and byte count are not the same thing. English letters and basic punctuation use 1 byte each. Most European accented characters (like e with accent or u with umlaut) use 2 bytes. Chinese, Japanese, and Korean characters typically use 3 bytes each. Emoji use 4 bytes.

So a 100-character message in English uses about 100 bytes, but the same message length in Chinese uses about 300 bytes, and the QR code will be three times as complex. This matters for physical size and scannability. If you are creating multilingual QR codes, test the actual byte length of your content rather than relying on character count. A 200-character limit in English does not mean 200 characters in every language.

Also note that some scanning apps on older Android devices do not handle UTF-8 correctly and may display garbled text for non-Latin scripts. Testing across devices is especially important for multilingual content.

Keep your message focused and concise. A QR code is not a document. Treat it more like a sticky note: one idea, clearly expressed. Use line breaks to separate pieces of information (most scanners preserve them), but avoid tabs and complex formatting. Leading and trailing whitespace can cause problems with some readers.

If your text includes a phone number or email address, format it consistently. Some scanning apps automatically detect phone numbers and offer to dial them, but only if the format is clean. For product labels, serial numbers, or inventory codes, plain alphanumeric text works best because it uses the more compact encoding mode. Avoid special characters like curly braces or angle brackets unless they are essential to your content.

Before printing, always test your QR code on at least two different phones using both the native camera app and a dedicated scanner app. What looks fine in your generator preview may behave differently in the real world.