I need to save some engineering files that need the thicknesses in the filename. Windows hates "/" or "\", so I can't use a simple fraction. Symbols like this...

⅓, ⅔, ⅕, ⅖, ⅗, ⅘, ⅙, ⅚, ⅛, ⅜, ⅝, ⅞

...are nice, but don't cover the full gamitt of dimensions (ie. 1/16").

In addition, Windows hates " in the filename, so I assume in is used instead?

  • 1
    $\begingroup$ Personally if I want to put an imperial measurement in a filename, I use decimals, e.g. 0.25in. I'm in the UK, however, and rarely have a need to do this. I have no idea if there's any accepted standard in the US where inches are more common. Why do you need the thickness in the filename? Part Number for the filename, and thickness in the drawing seems the safest and most robust way around this, although perhaps not the most convenient. $\endgroup$ Commented Aug 31, 2018 at 19:44
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    $\begingroup$ Why not use the underscore between numbers? ie 1_2 and 2_3 etc $\endgroup$
    – Solar Mike
    Commented Aug 31, 2018 at 20:05
  • $\begingroup$ @JonathanRSwift great suggestion with decimals. My only issue is that the material stock tends to be noted in fractions and so I'd rely on the machine operator to make the correct conversion back. $\endgroup$
    – Davbog
    Commented Sep 12, 2018 at 17:02
  • $\begingroup$ @SolarMike I considered this, but I see a potential issue with full digits and fractions. Ie. 1⅛" would look like 1 1_8. Gets even worse when version or part numbers are involved for files ie. Plane X v1-02 or Plane X 3421. $\endgroup$
    – Davbog
    Commented Sep 12, 2018 at 17:05

3 Answers 3


I've seen numerous formats in my experience.

Per some of the comments, sometimes you'll see a fraction represented with dashes, underscores, or as a decimal. I find that most often, decimals are used.

  • 1/2 = 1_2 ,1-2, 500
  • 5/16 = 5_16 , 5-16, 3125

When you have 1 1/2" then I see 1_500 where the underscore would represent the decimal point.

I don't think there is a standard per se, but you should be consistent with your naming. Also, make an info-graphic that describes your filename nomenclature.

Sometimes for standard sizes or increments or catalog items, things are represented just by a simple number. E.g.

  • 1/16" = 01
  • 1/8" = 02

and so on.

This graphic below is an excellent example(aside from the slash usage for a computer file name) Nomenclature Diagram

  • $\begingroup$ Thanks for the suggestion, although I do see a potential conflict with 1_2 representing 1/2" and 1_500 representing 1 1/2" because then the underscore acts as either or which could lead to a misread. $\endgroup$
    – Davbog
    Commented Sep 12, 2018 at 17:10
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    $\begingroup$ @Rogue-OP Correct. The underscore should represent either a decimal point or a slash for a fraction. Not both and not either or within a naming scheme. 1_2 would be 1.2 or 1/2. You pick the scheme which best suits your requirements. $\endgroup$
    – GisMofx
    Commented Sep 12, 2018 at 17:15
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    $\begingroup$ Gismofx thanks for your answer. Thanks to you I've learned that there is no official standard, but that a standard should be defined and explicitly explained within an organization and it's production network. $\endgroup$
    – Davbog
    Commented Sep 12, 2018 at 17:29

We use the left bracket. It looks the best in our opinion:

1/16" = 1[16 in.

3/8" = 3[8 in.

  • $\begingroup$ that's brilliant! $\endgroup$
    – Davbog
    Commented Oct 17, 2019 at 23:29

This generator can seemingly make any fraction you want in unicode:


I put ¹⁄₁₆ in my Windows filename just fine. [Ironically enough, before finding the converter, I came up with using Shayne Turner's left bracket (1[16) idea.]

As for indicating the inches measurement, I'm just using 2 single quotes instead of a double.


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