Convert HTM to HTML — Free Online Converter
Convert HTML Document (.htm) to HyperText Markup Language (.html) online for free. Fast, secure document conversion with no watermarks or registration...
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Upload your .html file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .html file when it's ready.
About HTML to HTML Conversion
The only difference between HTM and HTML files is the file extension. HTM originated from the 8.3 filename limitation on DOS and early Windows systems, where extensions could not exceed three characters. Modern systems have no such restriction, and the four-character .html extension is the standard across all web servers, browsers, and development tools. The file contents, encoding, and markup are identical between the two.
Converting HTM to HTML is essentially a file rename with optional cleanup — normalizing the extension to .html ensures compatibility with modern tooling, build systems, and deployment pipelines that expect the standard extension. Some web servers and static site generators are configured to serve only .html files, making this conversion necessary for web hosting.
Why Convert HTML to HTML?
Modern web development toolchains and frameworks (React, Next.js, Jekyll, Hugo) expect the .html extension. Deploying a site with .htm files to platforms like Vercel, Netlify, or GitHub Pages may result in broken links if the server's MIME type configuration does not recognize .htm. Converting to .html eliminates this risk and aligns with current web standards.
Additionally, SEO best practices favor consistent URL structures. If some pages use .htm and others use .html, search engines may index duplicate content or dilute page authority. Standardizing on .html creates a cleaner URL structure and simplifies canonical URL management.
Common Use Cases
- Standardize file extensions when migrating legacy sites from IIS to modern hosting
- Prepare HTM files for static site generators that require .html extensions
- Fix broken links on web servers configured to serve only .html MIME types
- Clean up legacy web archives by normalizing all page extensions to .html
- Ensure consistent file extensions before importing into CMS platforms
How It Works
This conversion copies the file content byte-for-byte and changes only the file extension from .htm to .html. No content parsing, transformation, or encoding changes occur. The HTML markup, DOCTYPE declaration, character encoding, scripts, styles, and all other content remain identical. This is the fastest possible conversion — essentially instantaneous regardless of file size.
Quality & Performance
The output is bit-for-bit identical to the input. There is zero quality loss, zero content change, and zero formatting difference. The only change is the file extension.
Device Compatibility
| Device | HTML | HTML |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No | No |
Tips for Best Results
- 1Set up 301 redirects from .htm to .html URLs when deploying to avoid broken links and preserve SEO value
- 2Use a batch conversion to process entire legacy site directories at once
- 3Update all internal links in the converted files to reference .html extensions
- 4Check your web server's MIME type configuration to confirm .html is properly mapped to text/html
Related Conversions
Converting HTM to HTML is a simple but important housekeeping step when modernizing legacy web content. The standard .html extension ensures compatibility with all modern web servers, development tools, and deployment platforms.