Find the minimum QR code version, module grid size, and printed dimensions for your message length, error correction level, and module size — using the ISO/IEC 18004 capacity table.
Results
Calculated
Minimum QR version
—
Smallest grid that fits your data
Error correction
—
Damage the code can survive
Printed size
—
Grid plus required quiet zone
Capacity used
—
Characters used of this version's max
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How to use this calculator
This calculator finds the smallest standard QR code that can hold your message. Enter the number of characters you plan to encode (for example, the length of a URL), pick an error correction level, and set the physical size of one module (square) when printed. Click Calculate to see the minimum QR version, its grid size, the printed dimensions, and how much of that version's capacity your message uses. Click Clear to reset all fields.
Understanding the inputs
QR codes come in 40 standard sizes ("versions"), from Version 1 (21×21 modules) to Version 40 (177×177 modules), where each version adds 4 modules per side: modules = 4 × version + 17. Each version also has four error correction levels — L, M, Q, and H — that trade data capacity for damage tolerance using Reed-Solomon error correction. This calculator uses the standard byte-mode (8-bit) capacity table from ISO/IEC 18004, the encoding mode used by virtually all real-world QR generators for URLs, mixed text, and Unicode content.
Interpreting the results
The minimum QR version is the smallest of the 40 versions whose byte-mode capacity, at your chosen error correction level, is greater than or equal to your character count. The printed size adds the standard 4-module quiet zone (blank margin) required on every side before converting the grid to millimeters using your module size. Capacity used shows how much headroom you have — a low percentage means the code could absorb more data before needing a bigger version; a percentage near 100% means you are close to forcing the next version up.
Frequently Asked Questions
How does the calculator pick the QR code version?
It looks up the smallest of the 40 standard QR code versions whose byte-mode data capacity, at your chosen error correction level, is greater than or equal to your character count. These capacities come from the published ISO/IEC 18004 table, the same table QR code generator libraries use.
What does the error correction level (L/M/Q/H) do?
QR codes use Reed-Solomon error correction so they can still be read even if part of the code is dirty, scratched, or covered. Level L recovers from about 7% damage, M about 15%, Q about 25%, and H about 30%. Higher levels use more of the code's codewords for redundancy, which leaves less room for data and can push you to a larger version.
What is the quiet zone and why does it change the printed size?
The quiet zone is the blank margin the standard requires around every QR code — at least 4 modules wide on each side — so scanners can distinguish the code from surrounding content. The printed size shown here adds that margin to the grid before converting to millimeters, which is why it is larger than the grid size times the module size alone.
Why would the same message need a bigger QR code at a higher error correction level?
Every QR version has a fixed number of codewords split between your data and error correction redundancy. Raising the error correction level from L to H reassigns more of those codewords to redundancy, so fewer are left for your actual message — often forcing the calculator to recommend the next larger version to fit the same text.