QR Code Capacity Calculator
The amount of data a QR code can carry is fixed by its version, error-correction level and data mode, all defined in the ISO/IEC 18004 standard. Pick a version, a correction level and a data mode and this tool returns the maximum number of characters that symbol can hold. The values are taken directly from the standard's capacity tables, not estimated.
How QR capacity is determined
Symbol size = (version * 4 + 17) modules square
Capacity = ISO/IEC 18004 table value for (version, ECC level, mode)
Higher version raises capacity; higher ECC lowers it
The capacity figures here are the standard's published maxima. For example version 1 (21x21 modules) at level L holds up to 41 numeric digits, 25 alphanumeric characters or 17 bytes.
Worked example: version 10, level M, alphanumeric
A version 10 symbol is 10 times 4 plus 17 = 57 modules square. At error-correction level M in alphanumeric mode the ISO/IEC 18004 table gives a maximum of 513 alphanumeric characters. Selecting numeric mode for the same version and level raises the limit to 846 digits.
QR code capacity: frequently asked questions
What determines how much data a QR code holds?
Three factors: the QR version (1 to 40, which sets the module grid size), the error-correction level (L, M, Q or H), and the data mode (numeric, alphanumeric, byte or kanji). Higher versions hold more; higher error correction holds less because more space is spent on recovery codewords.
What are the QR error-correction levels?
ISO/IEC 18004 defines four levels: L recovers about 7 percent of damaged codewords, M about 15 percent, Q about 25 percent and H about 30 percent. Higher levels survive more damage but reduce the data capacity at a given version.
Where do the capacity numbers come from?
The figures are the published maximum character counts from the ISO/IEC 18004 QR Code specification capacity tables. This tool stores those table values; it does not estimate them. The largest QR code (version 40, level L) holds up to 7,089 numeric digits.
Does the byte mode capacity depend on encoding?
Byte mode counts 8-bit bytes. For UTF-8 text a character may take 1 to 4 bytes, so the usable character count in byte mode depends on your text. The capacity figure here is the number of 8-bit bytes the symbol can store.
Official sources
- ISO/IEC 18004 QR Code bar code symbology specification: ISO catalogue listing.
- ISO standards portal: iso.org.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.