.MHTML file extension
To open .MHTML files on Windows, try double-clicking the .mhtml file to open it in your default browser (commonly Microsoft Edge or Google Chrome/Chromium, depending on your setup).
To open a .mhtml file, use a web browser that supports MHTML—commonly Google Chrome/Chromium or Microsoft Edge. You can usually open it by double-clicking the file or dragging it into an open browser window.
Last updated: June 12, 2026
Open on your device
Choose your operating system for a dedicated step-by-step opening guide.
How to open .MHTML files
Use these platform-specific instructions to open .MHTML files safely.
Windows
- Try double-clicking the .mhtml file to open it in your default browser (commonly Microsoft Edge or Google Chrome/Chromium, depending on your setup).
- If it does not open correctly: open Chrome/Edge, then drag the .mhtml file into the browser window (or use Ctrl+O and select the file).
Mac
- Open Google Chrome (or another Chromium-based browser you have installed).
- Drag the .mhtml file into the browser window, or use File → Open File… and select the .mhtml.
Linux
- Open Chromium or Google Chrome.
- Drag the .mhtml file into the browser window, or start the browser and use Ctrl+O to open the file.
iOS
- If your iPhone/iPad does not render the file well in a mobile browser, transfer the .mhtml to a desktop and open it with Chrome/Chromium or Edge.
Android
- Try opening the .mhtml in Chrome; if it does not display properly, transfer the file to a desktop Chrome/Chromium or Edge for viewing.
Security notes
- An .mhtml file is essentially a packaged web page; if it contains active web content, opening it in a browser can run page scripts or load referenced content depending on how it was saved and how the browser handles it. Treat MHTML from untrusted sources like any other web content you didn’t request.
- Because MHTML is a multipart MIME container, it can embed multiple different content types as separate parts. Be cautious with archives you did not create, especially if they appear to include unexpected attachments or content.
- Some enterprises manage MHT/MHTML handling in Microsoft Edge via policy (including rules about opening downloaded MHT/MHTML files). If your browser warns or blocks the file, follow your organization’s guidance rather than bypassing controls.
If you did not expect this file
This extension is usually plain data, text, or structured content—not a program by itself. The practical risk is social engineering (a scam attachment or misleading filename). For trusted senders you rarely need heavy-handed antivirus wording; use these tools when you want an extra check on unexpected downloads.
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Can't open this file?
These are the most common causes and fixes when .MHTML files fail to open.
Common reasons
- The file downloads but won’t open (or opens as plain text)
- Page looks incomplete or broken (missing images/CSS)
- Organization policy blocks opening downloaded .mht/.mhtml
Fix steps
- Open it from within a supporting browser (Chrome/Chromium or Microsoft Edge): use the browser’s Open File (Ctrl+O) or drag-and-drop the file into the browser.
- If double-clicking uses the wrong program, change the file association so your browser opens .mhtml by default.
OS-specific troubleshooting
What is a .MHTML file?
MHTML (also seen as .mht) is “MIME encapsulation of aggregate documents” where a web page and its referenced resources are bundled into one file. Technically it uses MIME multipart structures (commonly multipart/related) to embed the main HTML and each referenced resource as separate parts. The format is defined in RFC 2557 and is used as a “Save page as…” archive format in some browsers.
Background
MHTML is designed to capture a web page as a single portable file, keeping the page content and its dependencies together for archiving, transfer, or offline viewing. Instead of storing a folder of resources next to an .html file, MHTML stores everything as MIME parts inside one document.
In practice, MHTML is associated with web browsers and “save page” features. Chromium-based browsers support saving pages as MHTML (including via a command-line switch), and Chrome extensions can also capture the current tab as MHTML.
Because it is MIME-based, MHTML resembles email-style multipart messages: it has headers and multiple body parts. Different MIME types may be encountered in the wild for MHTML-related content (for example multipart/related and sometimes message/rfc822 are referenced in descriptions of the format), but the key idea is a single-file web archive built from MIME parts.
Common MIME types: multipart/related, message/rfc822
Known aliases: .mht
Further reading
Authoritative resources for more details on the .MHTML format.
Common .MHTML issues
The file downloads but won’t open (or opens as plain text)
Some apps don’t recognize .mhtml and will treat it like a generic text file even though it is a MIME multipart web archive.
- Open it from within a supporting browser (Chrome/Chromium or Microsoft Edge): use the browser’s Open File (Ctrl+O) or drag-and-drop the file into the browser.
- If double-clicking uses the wrong program, change the file association so your browser opens .mhtml by default.
Page looks incomplete or broken (missing images/CSS)
MHTML is supposed to embed resources as MIME parts, but some saved archives may be incomplete or rely on external URLs that were not captured.
- Re-save the page as MHTML from a Chromium-based browser to ensure resources are included (Chromium documents MHTML as a Save Page As option).
- If you received the file from someone else, ask them to re-capture it or provide the original page URL so you can save it again.
Organization policy blocks opening downloaded .mht/.mhtml
In managed environments, browsers may restrict how downloaded MHT/MHTML files are handled due to security controls and zone/mark-of-the-web style considerations.
- If you are using Microsoft Edge in a managed environment, check with your IT administrator—Edge policies exist that specifically govern opening downloaded MHT/MHTML files.
- As a workaround for legitimate use, view the content in a controlled environment (for example, a non-managed machine or isolated profile) if your organization allows it.
FAQ
What is the difference between .mhtml and .mht?
They are two common extensions for the same MHTML web archive format; both refer to a single-file archive that encapsulates an HTML page and its resources using MIME multipart structure.
How is an .mhtml file structured internally?
It uses MIME encapsulation (RFC 2557): typically a multipart/related message where the first part is the main HTML document and subsequent parts contain embedded resources (images, CSS, etc.).
Can Chrome save a page as .mhtml?
Yes. Chromium-based browsers support saving pages as MHTML, and Chrome extensions can capture a tab as MHTML using the pageCapture API.
Is MHTML an official IANA media type?
The common underlying type used for MHTML-style packaging is multipart/related, which is listed in the IANA media types registry. In practice, MHTML is associated with MIME types like multipart/related (and is also sometimes described alongside message/rfc822 in discussions of MHTML).
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