tech calculator

QR Code Data Capacity Calculator

Find the smallest QR version that holds your payload, in any encoding mode and error correction level.

QR capacity = data codewords x 8 bits, minus a 4-bit mode indicator and a version-dependent character count field. A version 40 code at error correction level L holds 7,089 digits, 4,296 alphanumeric characters, 2,953 bytes or 1,817 kanji. At level H the byte figure falls to 1,273, a drop of 56.9%.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Input

Payload

Encoding Mode

Error Correction Level

Force a Version (0 = use the smallest that fits)

Version 40 at level M in byte mode holds 2,331 characters — the absolute ceiling for a QR code.

Results

Smallest Version That Fits

Version 4

Data Length53 characters

Version ShownVersion 4

Symbol Size33 x 33 modules

Total Modules1,089

Data Codewords64

Data Bits Available512

Header Bits12 (mode indicator + character count)

Bits Used436

Spare Bits76

Capacity at This Version62 characters

Characters Remaining9 spare

Error CorrectionLevel M — recovers up to 15%

Absolute Maximum at This Level2,331 characters (version 40)

Tip

Useful whenever a QR code has to fit a fixed physical space, whenever a payload is close to the edge, and whenever you need to decide between error correction level M and level H before printing thousands of labels.

Formula

How QR capacity is calculated

Modules per side = 4 x Version + 17
Available data bits = Data codewords x 8
Bits used = 4 (mode indicator) + character count bits + payload bits

Payload bits per mode:
  Numeric        10 bits per 3 digits
  Alphanumeric   11 bits per 2 characters
  Byte           8 bits per byte
  Kanji          13 bits per character

Capacity is not a lookup here: it is derived from the ISO/IEC 18004 data-codeword count for the version and error correction level, minus a four-bit mode indicator and a character-count field whose width steps at versions 10 and 27. That is why capacity does not scale smoothly — a version 9 byte-mode symbol spends 8 bits on the character count and a version 10 symbol spends 16.

Step by step

How the calculation works

1Paste the actual payload rather than guessing its length. Byte mode encodes UTF-8 octets, so an emoji costs four bytes and an accented character two, which is the usual reason a QR code that fitted in testing overflows in production.
2Pick the encoding mode that matches your data. Numeric mode packs three digits into ten bits and alphanumeric packs two characters into eleven, so a purely numeric payload holds roughly 2.4 times as much as the same length in byte mode. Alphanumeric mode is uppercase only, plus digits, space, and the nine symbols $ % * + - . / and colon — a lowercase letter anywhere in the string forces byte mode for the whole thing.
3Error correction is a direct trade against capacity. Going from level L to level H on a version 40 symbol drops byte capacity from 2,953 to 1,273, a loss of 57 percent. Level M is the usual default; level Q or H earns its cost only when the code will be printed small, on a curved surface, or somewhere it will get dirty or partly covered.
4Watch the version number, not just whether it fits. Every version adds four modules per side, so a version 20 symbol is 97 modules across against 21 for version 1. Scanners need roughly two to three printed pixels per module to read reliably, so a high version on a small label is unscannable long before it is unencodable.
5The practical fix for an overflowing code is almost never a higher version. Shorten the URL, drop the query string, or point at a redirect. A short link in a version 3 symbol scans from across a room; the same destination spelled out in full at version 12 does not.
6Once you know the version and level you need, the [QR code generator](/calculators/qr-generator) produces the image itself, with control over margin, colour and resolution.

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Utility Tool

QR Code Generator

Generate the actual code once you know the capacity and error correction level you need.

Tech Tool

Base64 Encoder / Decoder

Base64 inflates payloads by a third — check what that does to your byte count first.

Tech Tool

Binary, Hex & ASCII Converter

Inspect the raw bytes behind a payload when a code will not encode as expected.

tech calculator

QR Code Data Capacity Calculator

Find the smallest QR version that holds your payload, in any encoding mode and error correction level.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Input

Payload

Encoding Mode

Error Correction Level

Force a Version (0 = use the smallest that fits)

Version 40 at level M in byte mode holds 2,331 characters — the absolute ceiling for a QR code.

Results

Smallest Version That Fits

Version 4

Data Length53 characters

Version ShownVersion 4

Symbol Size33 x 33 modules

Total Modules1,089

Data Codewords64

Data Bits Available512

Header Bits12 (mode indicator + character count)

Bits Used436

Spare Bits76

Capacity at This Version62 characters

Characters Remaining9 spare

Error CorrectionLevel M — recovers up to 15%

Absolute Maximum at This Level2,331 characters (version 40)

Tip

Summary

Key output metrics

Smallest Version That Fits

Version 4

33 x 33 modules

Capacity at This Version

62 chars

64 data codewords at level M

Space Used

85.2%

76 spare bits

D3 visualization

Capacity at Each Error Correction Level

The same symbol version holds progressively less data as more of its codewords are handed over to error correction.

Guide

How to understand and use this calculator

Quick Answer — How Much Data Can a QR Code Hold?

The ceiling is a version 40 symbol at error correction level L, which holds 7,089 numeric digits, 4,296 alphanumeric characters, 2,953 bytes, or 1,817 kanji characters. That symbol is 177 modules across and is essentially unscannable at label size, so the practical answer is always much smaller.

Capacity depends on three things: the symbol version (1 to 40), the encoding mode, and the error correction level.

Byte-mode capacity at level M, by version:

Version 1 — 21 × 21 modules, 14 bytes
Version 2 — 25 × 25, 26 bytes
Version 3 — 29 × 29, 42 bytes
Version 5 — 37 × 37, 84 bytes
Version 10 — 57 × 57, 213 bytes
Version 20 — 97 × 97, 666 bytes
Version 40 — 177 × 177, 2,331 bytes

Error correction is a straight trade against capacity. On a version 40 symbol, byte capacity falls from 2,953 at level L to 1,273 at level H — a drop of 56.9 percent to buy recovery from 30 percent damage instead of 7 percent.

How to Use This Calculator: A 53-Byte URL

Paste the URL into the payload box. The default link, pointing at this site's QR generator, is 53 bytes in UTF-8. Leave the mode on byte and the error correction level on M, which is the usual default.

The smallest version that fits is version 4, a 33 × 33 symbol with 1,089 modules. It has 64 data codewords, so 512 data bits. Your payload uses 436 bits — 4 bits of mode indicator, 8 bits of character count, and 8 bits per byte — leaving 76 spare bits. Capacity at that version is 62 characters, so you have 9 characters of headroom.

Switch the error correction level to H and the same URL needs version 6, a 41 × 41 symbol. Nothing about the data changed; twice as much of the symbol is now given over to recovery, and the code grew by eight modules per side.

Try a longer payload to see the effect scale. A 300-byte vCard at level Q needs version 16, an 81 × 81 symbol. That is four times the module count of the URL code, and at any fixed physical size each module is half the width.

The Formulas This Calculator Uses

Symbol size: modules per side = 4V + 17, where V is the version. Version 1 is 21 modules across and version 40 is 177.

Available data bits = data codewords × 8. The codeword count for each version and error correction level comes from ISO/IEC 18004.

Bits used = 4 (mode indicator) + character-count bits + payload bits.

Payload bits by mode: numeric packs 3 digits into 10 bits; alphanumeric packs 2 characters into 11 bits; byte uses 8 bits per byte; kanji uses 13 bits per character.

The character-count field is the part that trips people up, because its width steps with version: for byte mode it is 8 bits up to version 9 and 16 bits from version 10 onward. That step is why byte capacity at level M jumps from 180 at version 9 to 213 at version 10 rather than following a smooth curve — the symbol grew, and the header grew with it.

Because capacity is derived rather than looked up, the numbers here match the standard exactly at every version and level, including the awkward ones.

A Second Example: Why Numeric Mode Is Worth 2.4 Codes

Take a 20-digit serial number. In byte mode that is 20 bytes. In numeric mode it is 10 × ⌊ 20/3 ⌋ + 7 = 67 bits, against 160 bits in byte mode — less than half the space.

Scaled to the ceiling, a version 40 level L symbol holds 7,089 numeric digits against 2,953 bytes. Numeric mode is worth 2.4 times the capacity of byte mode for the same symbol.

Alphanumeric mode sits in between at 11 bits per two characters, but it comes with a hard restriction: uppercase letters and digits only, plus space and the nine symbols dollar, percent, asterisk, plus, hyphen, full stop, slash, colon and space. A single lowercase letter anywhere in the string forces the whole payload into byte mode. This is the most common reason a code that should have been small is not — an uppercase-only URL encodes in alphanumeric mode and the same URL in lowercase does not.

Version 3 at level M holds 61 alphanumeric characters but only 42 bytes. If your payload can be made uppercase without breaking anything, that is about 45 percent more room in the same 29 × 29 symbol.

Choosing an Error Correction Level, and Knowing When to Shorten Instead

The four levels recover from roughly 7, 15, 25 and 30 percent damage. Level M is the sensible default for a screen or a clean printed page. Level Q or H earns its cost when the code will be printed small, wrapped around something curved, exposed to weather or handling, or partly covered by a logo — which is the main legitimate reason to reach for H.

The cost is real and it compounds with size. Every step up the error correction ladder pushes the payload into a higher version, and every version adds four modules per side. A payload that needs a 33 × 33 symbol at level M needs 41 × 41 at level H, and at a fixed physical size that means each module is 20 percent narrower.

That module width is the practical scanning constraint, not the capacity. Scanners need roughly two to three printed pixels per module to read reliably, and the usual guidance is a module of at least 0.4 mm at typical scanning distance. A version 20 symbol on a 25 mm label gives modules a quarter of a millimetre wide, and no error correction level rescues that.

So when a code overflows, the fix is almost never a higher version. Shorten the URL, drop the tracking parameters, or point at a redirect that expands server-side. A short link in a version 3 symbol scans from across a room; the same destination spelled out in full at version 12 does not, no matter how much error correction you throw at it. Once the payload and level are settled, the QR code generator produces the image itself.

Limitations

Capacity is not scannability. This calculator tells you whether a payload encodes; it says nothing about whether the resulting symbol can be read at the size you intend to print it, under the lighting it will face, by the cameras your users have. Test the actual printed artefact.

The model assumes a single encoding mode for the whole payload. Real encoders can switch modes mid-symbol — numeric for a run of digits, byte for the rest — and a good one will fit slightly more than the single-mode figure shown here. Treating the payload as one mode is the conservative reading.

Structured append, which splits data across up to 16 linked symbols, is not modelled. Neither is ECI, the extended channel interpretation mechanism that declares a character encoding and costs a few extra bits.

Kanji mode capacity assumes Shift JIS double-byte characters, which is what the standard specifies. Japanese text encoded as UTF-8 goes through byte mode instead and takes considerably more room.

Related Calculators

This calculator answers the sizing question; the QR code generator produces the actual image, with control over margin, colour and output resolution. When a payload has been Base64-encoded, the Base64 encoder and decoder shows exactly how much the encoding inflated it — roughly a third, which is often the difference between a version 6 and a version 8 symbol. For inspecting the raw bytes when a code will not encode as expected, the binary, hex and ASCII converter is the quickest way to find the multi-byte character you did not know was there.

Related concepts

Symbol Version

The size of the QR symbol, 1 to 40. Modules per side equal 4 x version + 17, running from 21 across at version 1 to 177 at version 40.

Encoding Mode

How characters are packed into bits. Numeric fits 3 digits in 10 bits, alphanumeric 2 characters in 11 bits, byte 8 bits per octet, and kanji 13 bits per character.

Error Correction Level

L, M, Q or H, recovering from roughly 7, 15, 25 and 30 percent damage. Higher levels convert data codewords into recovery codewords and cut capacity accordingly.

Frequently Asked Questions

How much data can a QR code hold?+

At most, a version 40 symbol at error correction level L holds 7,089 numeric digits, 4,296 alphanumeric characters, 2,953 bytes, or 1,817 kanji characters. That symbol is 177 modules across and is impractical at label size, so real codes are far smaller — a 54-character URL at level M fits in a 33 by 33 version 4 symbol.

What are QR code versions?+

The version is the symbol size, numbered 1 to 40. Modules per side equal 4 times the version plus 17, so version 1 is 21 by 21 and version 40 is 177 by 177. Higher versions hold more data and need more physical space or finer printing to stay scannable.

How much capacity does error correction cost?+

A lot. On a version 40 symbol, byte capacity falls from 2,953 at level L to 1,273 at level H, a drop of 56.9 percent, in exchange for recovering from 30 percent damage instead of 7 percent. Level M is the usual default; go higher only when the code will be printed small, curved, weathered, or partly covered by a logo.

Why does making my URL uppercase make the code smaller?+

Because alphanumeric mode packs two characters into 11 bits against 8 bits per byte, but it only supports uppercase letters, digits, space and nine symbols. One lowercase character forces the entire payload into byte mode. Version 3 at level M holds 61 alphanumeric characters but only 42 bytes — nearly 50 percent more room in the same symbol.

Why do emoji break my QR code?+

Byte mode encodes UTF-8 octets, not characters. An emoji is four bytes and an accented Latin character is two, so a payload that looked like 50 characters can be 70 bytes. This calculator counts real UTF-8 length in byte mode, which is why a payload with emoji sometimes needs two versions more than expected.

What is the smallest QR code I can print?+

That is a module-width question rather than a capacity one. Scanners need roughly two to three printed pixels per module and typically a module of at least 0.4 mm at normal scanning distance. A version 20 symbol on a 25 mm label puts modules at a quarter of a millimetre, which no error correction level can rescue.

My code is too big. Should I raise the version?+

Almost never. Raising the version adds four modules per side and makes the code harder to scan at any fixed physical size. Shorten the payload instead: strip tracking parameters, use a short link, or point at a redirect that expands server-side. A short link in a version 3 symbol scans from across a room.

Why does capacity jump between version 9 and version 10?+

Because the character-count field widens. In byte mode it is 8 bits up to version 9 and 16 bits from version 10 onward, so the header grows at the same moment the symbol does. Byte capacity at level M goes from 180 at version 9 to 213 at version 10, and the curve has a visible kink at that point and again at version 27.

Formula

How QR capacity is calculated

Modules per side = 4 x Version + 17
Available data bits = Data codewords x 8
Bits used = 4 (mode indicator) + character count bits + payload bits

Payload bits per mode:
  Numeric        10 bits per 3 digits
  Alphanumeric   11 bits per 2 characters
  Byte           8 bits per byte
  Kanji          13 bits per character

Step by step

How the calculation works

1Paste the actual payload rather than guessing its length. Byte mode encodes UTF-8 octets, so an emoji costs four bytes and an accented character two, which is the usual reason a QR code that fitted in testing overflows in production.
2Pick the encoding mode that matches your data. Numeric mode packs three digits into ten bits and alphanumeric packs two characters into eleven, so a purely numeric payload holds roughly 2.4 times as much as the same length in byte mode. Alphanumeric mode is uppercase only, plus digits, space, and the nine symbols $ % * + - . / and colon — a lowercase letter anywhere in the string forces byte mode for the whole thing.
3Error correction is a direct trade against capacity. Going from level L to level H on a version 40 symbol drops byte capacity from 2,953 to 1,273, a loss of 57 percent. Level M is the usual default; level Q or H earns its cost only when the code will be printed small, on a curved surface, or somewhere it will get dirty or partly covered.
4Watch the version number, not just whether it fits. Every version adds four modules per side, so a version 20 symbol is 97 modules across against 21 for version 1. Scanners need roughly two to three printed pixels per module to read reliably, so a high version on a small label is unscannable long before it is unencodable.
5The practical fix for an overflowing code is almost never a higher version. Shorten the URL, drop the query string, or point at a redirect. A short link in a version 3 symbol scans from across a room; the same destination spelled out in full at version 12 does not.
6Once you know the version and level you need, the [QR code generator](/calculators/qr-generator) produces the image itself, with control over margin, colour and resolution.

Related guides

Learn more about this calculation

Guide

QR Code Data Capacity Calculator

Inputs

Results

How QR capacity is calculated

How the calculation works

Learn more about this calculation

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Understanding Calculator Formulas: How DTC Turns Inputs into Results

QR Code Generator

Base64 Encoder / Decoder

Binary, Hex & ASCII Converter

Key facts

Sources & methodology

QR Code Data Capacity Calculator

Inputs

Results

Key output metrics

Capacity at Each Error Correction Level

How to understand and use this calculator

Quick Answer — How Much Data Can a QR Code Hold?

How to Use This Calculator: A 53-Byte URL

The Formulas This Calculator Uses

A Second Example: Why Numeric Mode Is Worth 2.4 Codes

Choosing an Error Correction Level, and Knowing When to Shorten Instead

Limitations

Related Calculators

Related concepts

Frequently Asked Questions

How QR capacity is calculated

How the calculation works

Learn more about this calculation

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Understanding Calculator Formulas: How DTC Turns Inputs into Results

QR Code Generator

Base64 Encoder / Decoder

Binary, Hex & ASCII Converter

Key facts

Sources & methodology

Key output metrics

Capacity at Each Error Correction Level

How to understand and use this calculator

Quick Answer — How Much Data Can a QR Code Hold?

How to Use This Calculator: A 53-Byte URL

The Formulas This Calculator Uses

A Second Example: Why Numeric Mode Is Worth 2.4 Codes

Choosing an Error Correction Level, and Knowing When to Shorten Instead

Limitations

Related Calculators

Related concepts

Frequently Asked Questions