What Inside a QR Code?

A QR code can store binary data, which means it can theoretically contain almost any type of digital information. Unlike traditional barcodes, which only store numbers or short identifier strings, QR codes support more flexible encoding and therefore allow a wide range of content to be embedded directly in the symbol.

However, QR codes are not designed to replace full data storage systems. Their capacity is limited to roughly 3 KB when using 8-bit encoding. This limit makes it impractical to embed multimedia files (such as photos, audio, or long documents) directly inside a QR code. For that reason, images, music, videos, and larger texts are usually stored on a website or cloud service, and the QR code simply contains a URL pointing to that content.

Types of Information You Can Store in a QR Code

Despite the size limitation, QR codes are extremely versatile. They can hold many kinds of short, structured, and machine-readable data formats.

1. URLs and Web Addresses

The most common use case is linking to websites, online profiles, landing pages, social media, images, or files. A QR code can store almost any URL: YouTube videos, Facebook pages, online forms, homepages, and more.

2. Plain Text

Short notes, serial numbers, instructions, or any message that fits inside the 3 KB limit can be stored directly as text.

3. Contact Information

QR codes can embed standardized formats such as vCard or MeCard, making them ideal for digital business cards.
When scanned, the contact details can be saved immediately to a smartphone’s address book.

4. Telephone Numbers and SMS

A QR code can initiate a phone call or open the user’s SMS app with a predefined message.
This is often used in customer service or quick contact solutions.

5. Email Addresses and Pre-Filled Messages

QR codes can generate an email draft with a recipient, subject, and even body text.
Useful for support, feedback forms, or event registrations.

6. Wi-Fi Login Credentials

QR codes can store encrypted Wi-Fi SSID and password information, allowing devices to connect to a network instantly without typing.

7. Calendar Events

Formats like iCal allow QR codes to add events directly to a user’s calendar—helpful for conferences, tickets, and invitations.

8. Geographic and Navigation Data

QR codes can store coordinates or open map applications with navigation already set to a specific location.

Compatibility Considerations

Although QR codes can store many different data types, not all scanners support all formats. For example, some low-quality scanning apps may struggle with vCards, Wi-Fi credentials, or calendar entries. Modern smartphone cameras usually support the most common data types, but specialized formats may require a more advanced reader.

QR codes may have a modest data capacity, but they remain an incredibly flexible way to encode and share information. Whether you need to link to a website, share contact details, provide Wi-Fi access, or embed simple text, QR codes offer a compact and universally supported solution. For richer content like images or multimedia, the best practice is to store the large files online and let the QR code point the user directly to it.