The EOT file (.eot)

The basics

What is an EOT file?

Anatomy

What's inside an EOT file

An EOT file is a header describing the font, followed by the font itself. Below is our sample-regular.eot. Unlike TTF and WOFF, the header is little-endian: the low byte comes first, so 20 2E 00 00 is 0x2E20, which is 11,808.

offset  bytes                            meaning
000000  20 2E 00 00                      EOTSize: 11,808 bytes
000004  44 2D 00 00                      FontDataSize: 11,588 bytes
000008  01 00 02 00                      Version 0x00020001
00000C  00 00 00 00                      Flags: not compressed, not XOR-ed
000010  02 0B 05 03 00 00 00 00 00 00    PANOSE classification
00001A  01                               Charset: default
00001B  00                               Italic: no
00001C  90 01 00 00                      Weight: 400
000020  00 00                            fsType: installable embedding
000022  4C 50                            MagicNumber 0x504C
000024  03 00 00 00 … (24 bytes)         Unicode and code page ranges
00003C  E4 4F 4F 71                      CheckSumAdjustment, from head
000040  00 00 00 00 … (16 bytes)         Reserved
000050  00 00 20 00                      padding, FamilyNameSize: 32
000054  39 00 39 00 68 00 65 00 …        "99helpers Sample" (UTF-16)
000074  00 00 0E 00 52 00 65 00 …        StyleName "Regular"
000086  00 00 1A 00 56 00 65 00 …        VersionName "Version 1.000"
0000A4  00 00 30 00 39 00 39 00 …        FullName "99helpers Sample Regular"
0000D8  00 00 00 00                      padding, RootStringSize: 0
0000DC  00 01 00 00 00 0A 00 80 …        FontData: a complete TTF
002E20                                   end of file: 11,808 bytes

1. 120 2E 00 00

   The total size

   The whole file: header, names and font data. Because the file starts with its own length rather than a fixed signature, EOT files have no recognisable first bytes.

2. 244 2D 00 00

   The font data size

   How long the embedded font is: 11,588 bytes, exactly the size of our sample-regular.ttf.

3. 301 00 02 00

   The version

   0x00020001 (read backwards, as little-endian). Version 0x00010000 had no root string; 0x00020001 added it; 0x00020002 added a signature and support for end-user-defined characters (EUDC).

4. 400 00 00 00

   The flags

   Bits for a subset font (0x1), MicroType Express compression (0x4) and XOR obfuscation (0x10000000). All off in our samples, so the font data is readable as is.

5. 502 0B 05 03 … / 90 01 00 00 / 00 00

   Copied font details

   PANOSE classification, charset, italic flag, weight (0x190 = 400) and the fsType embedding permissions, copied from the font's OS/2 table so a browser could check them without unpacking the font.

6. 64C 50

   The magic number

   0x504C, stored little-endian as the bytes 4C 50 (ASCII LP) at offset 34. It's a corruption check, and the most reliable way to recognise an EOT file. The Unix file command looks for it.

7. 700 00 20 00 39 00 39 00 …

   The names

   Family, style, version and full name, each as a 2-byte padding field, a 2-byte length and UTF-16 text.

8. 800 00 00 00

   The root string

   A list of web addresses allowed to use the font. Empty here, so any site may; sample-root-string.eot carries https://99helpers.com/.

9. 900 01 00 00 00 0A 00 80 …

   The font data

   An ordinary TrueType font, starting with its own 00 01 00 00 signature. In most EOT files made for real sites, this part is MicroType Express-compressed and unreadable without decoding.

Under the hood

How an EOT file works

Related formats

EOT vs WOFF2, WOFF and TTF

Legacy code

The ?#iefix trick and other old @font-face code

/* The "bulletproof" syntax from around 2010. Only the first
   two lines were ever for EOT; current browsers skip them. */
@font-face {
  font-family: "Example";
  src: url("example.eot"); /* IE 9 in compatibility modes */
  src: url("example.eot?#iefix") format("embedded-opentype"), /* IE 6 to 8 */
       url("example.woff2") format("woff2"),
       url("example.woff") format("woff");
}

/* What the same rule needs today */
@font-face {
  font-family: "Example";
  src: url("example.woff2") format("woff2");
}

How to

How to open and convert an EOT file

# FontData sits at the end of an uncompressed EOT file,
# and FontDataSize (offset 4) says how long it is:
tail -c 11588 sample-regular.eot > extracted.ttf
ttx -l extracted.ttf

Rights and risks

Licences and security

Free downloads

Sample EOT files to download

Free sample EOT files for testing legacy font pipelines, converters, format detection and upload filters. They're uncompressed Embedded OpenType (version 0x00020001, no MicroType Express, no XOR) wrapping 99helpers Sample, an original geometric typeface we drew for these pages. Browsers can't preview EOT, so there's no live specimen; the same font is shown on the TTF page.

What's inside sample-regular.eot

We wrote the header byte by byte following the W3C submission, then read it back with a separate parser to check every field.

1. Sizes

   EOTSize 11,808 and FontDataSize 11,588, little-endian, at offsets 0 and 4.

2. Version and flags

   Version 0x00020001, flags 0: not subset, not compressed, not XOR-ed.

3. Font properties

   PANOSE 02 0B 05 03 … (sans serif, medium weight), weight 400, fsType 0 and the Unicode ranges, all copied from the font's OS/2 table.

4. Magic number

   4C 50 at offset 34, which is how tools such as file recognise the format.

5. Names

   "99helpers Sample", "Regular", "Version 1.000" and "99helpers Sample Regular" in UTF-16, then an empty root string.

6. Font data

   A complete TrueType font from offset 0xDC to the end, with the licence and a link back to this page in its name table.

All sample EOT files

• Regular weight, uncompressed

  sample-regular.eot · 11.5 KB (11,808 bytes)

  99helpers Sample Regular as EOT version 0x00020001, no compression, no XOR, no root string. The embedded TTF can be cut out with tail.

  • Testing EOT parsers and converters
  • Checking format detection by the `4C 50` magic number
  Download

• Bold weight, uncompressed

  sample-bold.eot · 11.3 KB (11,576 bytes)

  The same family at weight 700: the header's Weight field is 700 (BC 02 00 00) and the PANOSE weight byte is 8.

  • Testing that converters keep weight and style
  • Legacy `@font-face` set-ups with two weights
  Download

• EOT with a root string

  sample-root-string.eot · 11.6 KB (11,854 bytes)

  The regular font with a root string of https://99helpers.com/ (46 bytes of UTF-16 including the closing null), which in Internet Explorer limited the font to pages on that site.

  • Testing parsers that read or strip root strings
  • Seeing how the header grows with a root string
  Download

Ways to test with them

• Format detection: EOT has no signature at offset 0. A detector should check for 4C 50 at offset 34, and that the first four bytes equal the file size.
• Converters: convert sample-regular.eot to TTF and compare with ttx -l; you should get the ten tables of the TTF sample.
• Extraction: tail -c 11588 sample-regular.eot gives a valid TTF, because the font data is stored uncompressed at the end.
• Browsers: load sample-regular.eot with @font-face or the FontFace API in a current browser: it is rejected (Chromium reports invalid font data), which confirms nothing still depends on it.

Free to use for testing, teaching and demos, commercially or not, with no attribution needed. A link back to this page is always appreciated.

Questions

EOT files, frequently asked