Convert Any File to Base64 Online
Convert any binary file (ZIP, PDF, DOCX, etc.) to Base64 text or reconstruct original files from Base64 strings safely.
Drag & drop file here or click to browse
Supports any file up to 25 MB. Processed entirely in your browser.
This file seems to already contain Base64 encoded text. Did you mean to decode it instead?
Base64 Output is Very Large
To prevent your browser from lagging, rendering has been limited. The full Base64 text is safely stored in memory.
Drag & drop Base64 file or click to browse
Text file containing Base64 string (Max 25MB)
Converting Binary Files to Base64: Developer Guide
Base64 file encoding allows developers to transmit PDFs, documents, audio clips, and archives across text-only protocols like JSON APIs, XML SOAP envelopes, and database BLOB fields.
Primary Use Cases for File Base64 Conversion
API File Uploads
Embedding PDF invoices or attachments inside REST / GraphQL JSON request bodies without requiring multi-part form data uploads.
Database Storage
Storing small configuration files, SSL certificates, or user document snippets directly in text database fields (MongoDB, PostgreSQL JSONB).
Email Attachments (MIME)
Converting binary email attachments into RFC 2045 compliant Base64 character streams for SMTP transport.
Calculating Base64 Encoded File Size
Formula: Encoded Size (Bytes) = Math.ceil(Original File Size / 3) * 4 + Padding
• 1 MB PDF File (~1,048,576 Bytes) → ~1.39 MB Base64 String
• 10 MB ZIP File (~10,485,760 Bytes) → ~13.98 MB Base64 String
Frequently Asked Questions (FAQ)
How do I convert a file to Base64 online?
Drag and drop any file up to 25MB into our online file converter. The browser reads the file locally via HTML5 FileReader API and converts its raw binary content into a Base64 string instantly without uploading it to any external server. Once the conversion is complete, you can copy the raw Base64 string or download it as a text file, keeping your files and data entirely secure.
What is the maximum file size I can convert to Base64?
Our online Base64 file converter is optimized to support files up to 25 megabytes in size. Because all file processing and conversion tasks are performed locally in your web browser's memory using client-side JavaScript, larger files can sometimes cause memory limitations in certain mobile browsers. Keeping the limit at 25MB ensures fast, reliable, and smooth performance for documents, images, audio clips, and compressed archives without freezing your browser interface. This makes it ideal for handling PDFs, ZIP files, and other assets commonly used in web applications.
How do I decode a Base64 string back to its original file?
To decode a Base64 string back to its original file, go to the Decode File tab, paste the Base64 string, and click the Download File button. Our tool parses the Base64 string, determines its underlying MIME type, and reconstructs the original binary bytes. A browser download prompt will appear, allowing you to save the restored file with the correct extension directly to your local storage, without sending any files over the internet. This local reconstruction process ensures that your downloaded documents, spreadsheets, and archives remain completely confidential and safe from interception.
What file types can be converted to Base64?
Any type of computer file can be converted to Base64. Since Base64 converts raw binary bytes into text, it is completely independent of file formats. You can convert PDF documents, ZIP archives, spreadsheets, Word documents, audio files (like MP3 or WAV), video files (like MP4), and executables. Once encoded, the resulting string can be safely embedded in JSON databases, XML configurations, API request bodies, or HTML source files without risk of transmission corruption. This versatility makes it a valuable utility for developers needing to serialize assets for configuration files or databases.
Why is my Base64 file output larger than the original file?
Base64 encoding increases file size by exactly 33.3% compared to the original binary file. This expansion happens because the Base64 scheme represents groups of three binary bytes (24 bits) using four ASCII characters (32 bits, since each character is stored as an 8-bit byte). In addition, padding characters at the end add a tiny overhead. When embedding files as Data URIs in web pages, you should consider this 33% size increase, as it can affect page load times. For this reason, base64 encoding is typically reserved for small assets, while larger files are kept in their native binary formats.