QR Code Data Types and Encoding
A QR code can encode any of four low-level data types — numeric, alphanumeric, byte/binary (used for URLs and UTF-8 text), and kanji — and at its largest size (version 40, error-correction level L) holds up to 7,089 digits, 4,296 alphanumeric characters, 2,953 bytes, or 1,817 kanji characters. On top of those raw modes, structured formats layer common real-world payloads: web URLs, WiFi credentials, vCard/MeCard contacts, email and SMS messages, geographic coordinates, calendar events, cryptocurrency addresses, and TOTP two-factor secrets.
That is the summary an AI overview will give you. What it can't tell you is which mode your data actually lands in, how much of it will fit, and how each payload format is structured — the details that decide whether your code scans on the first try. The rest of this guide gives you the capacity table, the payload formats, and the trade-offs.
Want to encode any of these data types right away? Try our free QR Code Generator to turn a URL, text, WiFi credentials, or contact info into a scannable QR code instantly.
The Four Encoding Modes and Their Capacity Limits
Under the hood, every QR code stores data in one of four native modes. An encoder automatically picks the most compact mode for your data (and can switch modes within a single symbol), so the type of characters you use has a direct impact on how much fits. The table below shows the absolute maximums at the largest symbol size — version 40 (a 177×177 grid) — at each error-correction level.
| Encoding mode | Characters supported | Bits per char | Max (ECC L) | Max (ECC M) | Max (ECC Q) | Max (ECC H) |
|---|---|---|---|---|---|---|
| Numeric | Digits 0–9 | ~3.33 (10 bits / 3 digits) | 7,089 | 5,596 | 3,993 | 3,057 |
| Alphanumeric | 0–9, A–Z (upper), space, $ % * + - . / : | 5.5 (11 bits / 2 chars) | 4,296 | 3,391 | 2,420 | 1,852 |
| Byte / binary | Any 8-bit data (ISO-8859-1 or UTF-8) | 8 | 2,953 | 2,331 | 1,663 | 1,273 |
| Kanji | Shift JIS double-byte (Japanese) | 13 | 1,817 | 1,435 | 1,024 | 784 |
Two practical takeaways: numeric mode holds more than twice as much as byte mode, so an all-digits payload (an order number, a phone number) stays small and easy to scan; and every step up in error correction costs you roughly 20–30% of capacity in exchange for damage resistance. URLs, emoji, and any non-ASCII text land in byte mode via UTF-8, where multi-byte characters count as 2–4 bytes each against the 2,953-byte ceiling. For the full error-correction trade-off, see QR code error correction levels and which you should use.
Common Payload Types and Their Formats
Above the raw encoding modes, QR readers recognize structured text prefixes that trigger specific device actions — opening a URL, joining a WiFi network, saving a contact. These formats are what most people actually generate. Here are the most common, with the exact syntax each uses:
| Payload type | Format / prefix | Example | What scanning does |
|---|---|---|---|
| Website URL | https://… | https://inventivehq.com | Opens the link in a browser |
| Plain text | (raw text) | Get 20% off: SPRING20 | Displays the text |
| WiFi | WIFI:T:WPA;S:ssid;P:pass;; | WIFI:T:WPA2;S:CafeGuest;P:latte123;; | Offers one-tap network join |
| vCard contact | BEGIN:VCARD…END:VCARD | Name, phone, email, org fields | Saves a contact |
| MeCard contact | MECARD:N:…;TEL:…;; | MECARD:N:Doe,Jane;TEL:5551234;; | Saves a contact (iOS-friendly) |
mailto: or MATMSG: | mailto:help@example.com?subject=Hi | Opens a pre-filled email | |
| SMS | smsto: / SMSTO: | SMSTO:5551234:JOIN | Opens a pre-filled text message |
| Phone call | tel: | tel:+18005551234 | Starts a phone call |
| Geo location | geo:lat,lng | geo:37.7749,-122.4194 | Opens the map location |
| Calendar event | BEGIN:VEVENT… (iCal) | Title, start/end, location | Adds an event to the calendar |
| Crypto payment | bitcoin: / ethereum: | bitcoin:bc1q…?amount=0.01 | Opens a wallet with details filled |
| TOTP 2FA | otpauth://totp/… | Account, secret, issuer, algorithm | Provisions an authenticator token |
Note that only a subset of these are official standards — vCard, MeCard, iCalendar, geo:, tel:, mailto:, and smsto: are widely supported URI schemes, while the WiFi and otpauth:// formats are de facto conventions that most modern scanners honor. When in doubt, test on both iOS and Android before printing at scale.
Text and Basic Data Types
Plain Text
QR codes can encode simple plain text messages. This is useful for:
- Short promotional messages
- Discount codes or coupons
- Instructions or warnings
- Reference numbers or identification codes
Plain text encoding is efficient and works across all scanning applications. For example, you could encode "Get 20% off with code SPRING20" as plain text that displays when scanned.
Numbers
QR codes support numeric-only encoding, which is the most space-efficient mode. This is ideal for:
- Product codes and SKUs
- Reference or tracking numbers
- Phone numbers
- ID numbers or credentials
Numeric mode uses the least data per character, allowing longer sequences of digits in smaller QR codes.
Alphanumeric Data
Alphanumeric encoding supports uppercase letters, digits, and certain special characters (space, $, %, *, +, -, ., /, :). This is useful for:
- Promotional codes (often uppercase: "SUMMER2024")
- Product model numbers
- Part numbers
- License plates or registration codes
Network and Communication Data
URLs and Web Links
The most common use case, URLs allow QR codes to link directly to:
- Marketing websites and landing pages
- Product pages in e-commerce stores
- Video hosting sites like YouTube
- Articles and blog posts
- Mobile app download pages
URLs can be long (hundreds of characters) and include query parameters to track campaigns, identify QR code locations, and pass additional context to the linked page.
Email Addresses
QR codes can encode email addresses for quick email composition:
- Contact forms
- Support requests
- Newsletter subscriptions
- Feedback submission
When a user scans an email QR code, their device opens the default email client with the recipient address pre-filled.
Email with Subject and Body
More advanced email encoding allows pre-filling subject lines and message bodies. For example, a support QR code could encode an email that opens with a specific subject and partially completed message, making it easier for users to contact support.
Phone Numbers
QR codes can encode phone numbers in a format recognized by mobile devices:
- Click-to-call functionality for smartphone users
- Business contact information
- Customer service hotlines
- Emergency numbers
When scanned, the phone number is recognized and users can directly initiate a call.
SMS Messages
QR codes can encode SMS (text message) data, automatically populating:
- Recipient phone numbers
- Message text
This is useful for:
- Customer feedback surveys
- Contest entry codes
- Appointment reminders
- Service request systems
Contact Information
vCard Format
QR codes commonly encode vCard (Virtual Card) format, which is an international standard for electronic business cards. vCards can include:
- Full name
- Phone number(s) (mobile, work, home)
- Email address(es)
- Organization/company name
- Job title
- Physical address
- Website URL
- Photo/image
When scanned, the contact information is automatically imported into the user's contacts application. This is extremely common on business cards, making it easy to exchange contact details without typing.
MeCard Format
Apple introduced MeCard format as an alternative to vCard. It supports similar information and is often preferred for compatibility with iOS devices.
Location Information
Geographic Coordinates
QR codes can encode latitude and longitude coordinates, which allow:
- Marking specific locations on maps
- Geocaching
- Location-based services
- Navigation to specific addresses
When scanned, the coordinates open in the user's default maps application.
vCard with Address
As mentioned above, vCards can include complete physical addresses with geographic interpretation.
WiFi Connection Data
WiFi Network Credentials
QR codes can encode WiFi network connection information including:
- Network SSID (name)
- Authentication type (open, WEP, WPA, WPA2, WPA3)
- Password (encrypted in the QR code)
This is extremely useful for:
- Coffee shops and restaurants providing guest WiFi
- Hotels enabling guest network access
- Events and conferences
- Retail locations
When users scan a WiFi QR code, their device automatically connects to the network without requiring manual entry of credentials.
Calendar and Event Data
Calendar Events (iCal Format)
QR codes can encode calendar event data in iCalendar format, including:
- Event title
- Date and time
- Duration
- Location
- Description
- Organizer details
Scanning a calendar QR code automatically creates an event in the user's calendar application. This is useful for:
- Conference and event invitations
- Meeting scheduling
- Appointment reminders
- Class or course registration
Payment Information
Payment Requests
Some QR code applications support encoding payment information:
- Cryptocurrency addresses (Bitcoin, Ethereum, etc.)
- Bank transfer details (IBAN, BIC codes)
- PayPal or Stripe payment links
- Mobile payment service links (Apple Pay, Google Pay)
These are particularly useful for point-of-sale systems, invoices, and accepting donations.
Authentication and Security Data
One-Time Passwords (OTP)
QR codes can encode Time-based One-Time Password (TOTP) information used by two-factor authentication applications like Google Authenticator, Authy, and Microsoft Authenticator. The QR code contains:
- The account identifier
- The shared secret key
- The time-step value
- The hash algorithm used
Users scan this QR code during authentication app setup to securely provision their two-factor authentication without manually typing the shared secret.
Digital Signatures and Certificates
Advanced QR code implementations can encode:
- Digital signatures for document verification
- Certificate data for secure transactions
- Blockchain-based authentication tokens
Business and Retail Data
Product Information
QR codes on product packaging can link to:
- Ingredient lists and allergen information
- Nutritional data and certifications
- Authenticity verification
- Product reviews and ratings
- Supplier information
- Recycling instructions
Loyalty Programs
QR codes can encode:
- Customer loyalty card information
- Membership details
- Reward points balances
- Personalized offers based on customer ID
Inventory and Supply Chain
QR codes can store:
- Product Serial numbers
- Batch or lot numbers
- Manufacturing dates
- Expiration dates
- Storage location information
- Supply chain tracking data
Limitation Considerations
When deciding what data to encode in a QR code, consider:
Storage Capacity: Larger data requires larger QR codes. Byte-mode data (like URLs with special characters) uses more space than numeric data.
Readability: Larger QR codes are less convenient. Some designers prefer encoding just a minimal identifier (like an order number) that links to a database, rather than encoding all data directly.
Security: Sensitive information should be encrypted or protected. QR codes containing passwords or personal information should include additional security measures.
Durability: Complex QR codes with higher error correction levels are more robust but require more space.
Compatibility: Some data types (like vCard with extended fields) may not be recognized by all applications.
Best Practices for Encoding Data
Encode Minimally: Only encode necessary information. For lengthy data, use a QR code to link to a database or service where detailed information resides.
Use Appropriate Modes: Numeric mode for numbers, alphanumeric for codes, byte mode for URLs and complex text.
Test Thoroughly: Always test QR codes with multiple applications and devices before production deployment.
Consider Error Correction: For codes in harsh environments, use higher error correction levels (Q or H).
Choose Size Appropriately: Balance readability (larger codes are easier to scan) with design constraints.
Use HTTPS for URLs: Always link to secure URLs to prevent man-in-the-middle attacks.
Conclusion
The versatility of QR code data encoding makes them applicable to diverse use cases beyond simple URL shortening. From WiFi credentials and contact information to calendar events and payment details, QR codes can efficiently encode various data types. Understanding which data types your QR code should contain, how they affect code size and complexity, and how to optimize encoding ensures that your QR codes are both functional and practical for your intended application. Whether used in marketing, supply chain management, or customer engagement, QR codes remain powerful tools for encoding rich information in compact, scannable formats.