QR code glossary · Encoding and capacity
Data capacity
Also called: QR code capacity
Definition
Data capacity is the most content a QR code can hold, which depends on its version, error correction level and encoding mode; the largest code, version 40 at level L, holds 7,089 numeric digits, 4,296 alphanumeric characters, 2,953 bytes or 1,817 kanji characters.
How it works
Each version has a fixed number of codewords. The error correction level decides how many of them carry data, and the encoding mode decides how many characters fit in each bit. A little space also goes to a mode indicator and a character count.
| Level | Numeric | Alphanumeric | Bytes | Kanji |
|---|---|---|---|---|
| L | 7,089 | 4,296 | 2,953 | 1,817 |
| M | 5,596 | 3,391 | 2,331 | 1,435 |
| Q | 3,993 | 2,420 | 1,663 | 1,024 |
| H | 3,057 | 1,852 | 1,273 | 784 |
At the other end, version 1 at level L holds 41 digits, 25 alphanumeric characters or 17 bytes, and at level H only 17 digits or 7 bytes. A byte is not always a character: in UTF-8, accented letters take two bytes and most emoji take four.
Why it matters
The maximums are theoretical. A version 40 code is far too dense for a phone at any normal print size, so the useful question is how small the content can be, not how much fits. A QR code also cannot hold a file: a code “for a PDF” or video contains a link to it, and a contact card with a photo is far beyond any QR code’s capacity.
To keep codes easy to scan, encode short content, prefer a short URL over a long address, and leave out optional fields.
Example
| Content | Characters | Version |
|---|---|---|
| Short link | 28 | 3 (29 × 29) |
| WiFi login | 41 | 3 (29 × 29) |
| MECARD with name, phone and email | 59 | 4 (33 × 33) |
| Link with three UTM tags | 90 | 6 (41 × 41) |
| vCard 3.0 with name, phone and email | 115 | 7 (45 × 45) |
In CirculateQR
The free generators warn you when content will make a dense code, and dynamic codes keep only a short link in the pattern, whatever the destination.
Related terms
- QR code versionA QR code’s version is its size on a scale from 1 to 40: version 1 is 21 × 21 modules and each version adds 4 modules per side, up to 177 × 177 at version 40, so a version V code is 17 + 4V modules across.
- Encoding modesEncoding modes are the ways a QR code packs characters into bits: numeric mode for digits, alphanumeric mode for a 45-character set of capital letters, digits and a few symbols, byte mode for any data such as UTF-8 text, and kanji mode for Japanese Shift JIS characters.
- Error correction levelAn error correction level is the setting, L, M, Q or H, that decides how much redundant data a QR code carries; the four levels let a scanner restore roughly 7%, 15%, 25% and 30% of the code’s codewords when they are damaged, dirty or covered.
- Short URLA short URL is a brief web address, such as example.com/r/A7K2Q9, that a server forwards to a longer destination; dynamic QR codes encode one so the printed pattern stays small and the destination can change without reprinting.
- vCard QR codeA vCard QR code is a QR code that contains contact details in vCard format, the standard text format for electronic business cards, so that scanning it makes a phone offer to save the name, phone number, email and other fields as a new contact.
Learn more
- QR code size guide: How dense content changes the print size.
- How to make a vCard QR code: Which contact fields to keep.
- Free text QR code generator: Put a short note in a code that works offline.
Sources
Last updated . Written by the CirculateQR team; technical facts follow the sources listed above. Example codes and sizes are computed with the open-source qrcode encoder that CirculateQR uses. Spotted something wrong? Email support@circulateqr.com. QR Code is a registered trademark of DENSO WAVE INCORPORATED.
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