About HTM Files
HTML Document (short)
HTM is an alternative extension for HTML files, functionally identical to .html. Common on older Windows systems.
Family
Documents & Text
Extension
.htm
MIME Type
text/html
Can Use As
HOW HTM
CAME TO BE.
The .htm extension is pure DOS baggage. When HTML emerged in 1993 as Tim Berners-Lee\u2019s hypertext markup language, filenames on DOS/Windows FAT16 filesystems were limited to the "8.3" format — eight characters for the name plus three for the extension. ".html" had four characters and simply didn\u2019t fit. Windows 95 lifted that limit with long filenames (VFAT), but .htm was already burned into every web server config, every tooltip, every FTP upload workflow. So both .htm and .html coexist indefinitely as aliases for the same HTML content.
Most modern toolchains default to .html, but static site generators that trace back to the 1990s (like FrontPage-era CMSes) still sprinkle .htm files across legacy sites. Every browser, server, and OS treats them identically.
CURIOSITIES &
TRIVIA.
.htm exists because 1990s DOS filesystems only allowed 3-character file extensions — ".html" was one letter too long.
Windows 95 added long filename support in 1995 but .htm was already embedded in millions of tutorials and server configs.
"Home.htm" is still the default landing page in some legacy Windows IIS installations.
Browsers and servers treat .htm and .html as identical — the distinction is cosmetic.
FrontPage 98 defaulted to .htm; Dreamweaver defaulted to .html — a small quirk in two CMSes that shaped millions of websites.
STRENGTHS &
LIMITATIONS.
Strengths
- Identical content to .html in every respect.
- Universally supported by every browser and server.
- 8.3 compatibility for antique DOS/Windows shares.
Limitations
- No real reason to use .htm over .html in 2026.
- Inconsistent with modern naming conventions.
- Mixed extensions within one site confuse static-site generators.
Typical Sizes & Weights
Legacy landing page
5-50 KB
Technical Specifications
- MIME type
- text/html
- Extension
- .htm
- Standard
- HTML Living Standard (WHATWG)
- Alias of
- .html
- Origin
- DOS 8.3 filename limit
CONVERT FROM
HTM
Common Use Cases
Legacy web pages, Windows compatibility
Popular HTM conversions
The most-requested destinations when starting from HTM.
Frequently Asked Questions about HTM
Frequently Asked Questions
HTM (HTML Document (short)) is a document format used to store paginated text, with optional formatting, tables, images, hyperlinks, headers and footers. It sits in the documents & text family and is typically associated with a specific office suite or publishing pipeline that defined the format and ships the canonical reader.
Modern office suites — Microsoft Word, Google Docs, LibreOffice Writer, Apple Pages — open most HTM files with reasonable fidelity. If your installed software does not support HTM, convert to DOCX or PDF first using KaijuConverter; both open in virtually every reader, including free online viewers.
Upload the HTM to KaijuConverter and pick DOCX, PDF, ODT, RTF, HTML, Markdown, or plain text. Our pipeline runs LibreOffice headlessly plus pandoc for text formats — the same engines behind professional document pipelines. Styles, tables, images, and hyperlinks survive the conversion intact.
Yes, to a high degree. Standard fonts, headings, lists, tables, images, hyperlinks and page structure transfer cleanly. Custom fonts substitute to the closest match if not embedded; obscure layout features unique to HTM (frames, legacy macros) may flatten to static content in the target format.