How to find the right round file

You can resharpen the cutting teeth of your chipper-tooth chain with a round file on your own. But a word of caution: not every saw chain is the same. The tool you use needs to match the respective saw chain, because if the wrong file is used, it can diminish the cutting performance of the chain. We explain below how to find the right round file.

STIHL round file for saw chains

STIHL round file for saw chains

Selecting the right round file depends on the chain pitch of the saw chain. Each chain pitch is assigned to a specific round file diameter.

The chain pitch assigns the saw chain to particular chainsaw models (power classes). To determine the pitch, measure the distance from the centre of one rivet to the centre of the next but one and then divide the measurement by two. The result is the chain pitch in millimetres. However, since the chain pitch is always given in inches, you will then need to convert the result (1 millimetre = 0.039 inches).

For STIHL saw chains, a number to identify the chain pitch is located on the outer edge of the depth gauge. Read our article “How a STIHL saw chain functions” to find out about the construction of a STIHL saw chain. In our example it is number 3.

The chain pitch code number

The chain pitch code number is located on the depth gauge

The larger the chain pitch, the higher the tooth. The higher the tooth, the larger the file needs to be.

If the number on the depth gauge is no longer legible, the chain pitch can be determined using a test gauge for chains.

Subsequently you can find the necessary file diameter using the STIHL conversion table:

STIHL conversion table to find the right round file

STIHL conversion table to find the right round file based on chain pitch

A word of caution: Please note that saw chain files have a different profile, i.e. a different surface structure, than engineer’s files, for example. The latter are therefore unsuitable to file saw chains.

All STIHL files are available at your local STIHL dealer.

On our website, you will find a detailed tutorial on how to sharpen saw chains.

Note: Only side-plate and top-plate cutting edges are sharpened with a round file. You should file back the depth gauge using a flat file so that it keeps its shape.

If you want to sharpen the cutting teeth and file back the depth gauge at the same time, we recommend you to use the STIHL 2-in-1 file holder.

All mentioned STIHL products are available at your local STIHL dealer.

Read comments and comment:

12 thoughts on “How to find the right round file

  1. Should I use a 5/32″ round file on a still chain 71 PM3 (10″ micro chain) ?

    Or, should I use a 1/8″ round file as listed in my sharpening tool ( special accessories) in my Stihl HT 56 C manual and also on the replacement chain box?

    I am confused for sure!!!

    1. Hello Bernard,
      Thank you for your comment.
      Please use a roundfile with 1/8″ (3,2 mm) diameter for resharpening your 71PM3 chain as mentioned in the manual and in our blogpost.
      Best regards,
      your STIHL team

    1. Hello Ed,
      Thank you for your comment.
      For STIHL saw chains, a number to identify the chain pitch is located on the outer edge of the depth gauge. You can find the necessary file diameter using the STIHL conversion table above.
      Best regards,
      your STIHL team

  2. I have a ms 150 tc chainsaw and was wondering what size round file to use to sharpen the chain .
    I measured the distance between the pins and it was 12.5 mm or (.492) and divided by 2 =.246
    1/4 pitch and by your chart , I should use a 4mm round file , or a 5/32″ .
    When I bought the saw they gave me a 1/8 ” round file , doesn’t fit with your formula .
    Was wondering should I use a 5/32 ” round file ?
    Thanks for any help .

    1. Hello Jimmy Inman,
      Thank you for your comment.
      Your calculation is basically correct. However, please note that the MS 150 TC uses a ¼’’ P chain. It requires a smaller file diameter of 3.2 mm or 1/8’’ for sharpening.
      Best regards,
      your STIHL team

  3. Why not complete the table above with file size converted to inches as well? My files are marked in fractions only and the table is not much quick help. My chain is marked with a 3 on depth guide yet the files supplied in my used kit are 3/16″ and 5/16″ neither of which converts to .2028, the product of .039 times 5.2. What am I missing?

    1. Hello Bernard Krystkowiak,
      Thank you for your comment.
      If your chain is marked with a “3” on the depth gauge, please use a roundfile with an diameter of 5,2 mm (13/64“) as mentioned in our blogpost.
      The 3/16″ file can be used to sharpen .325“ chains and the 5/16″ sould be used for ¼ P.
      Best regards,
      Your STIHL team

  4. our fire department has a MS 460 there is nothing on the depth gauge but a 6 on the part that runs in the grove of the bar… looking for correct file size to buy.

    1. Hello LT Jeff Goodwin,
      Thank you for your comment.
      Based on the information you provided, we assume that your chain has a pitch of 3/8”. This means you would be able to use a round file with a diameter of 5.2 mm, meaning 13/64”.
      Best regards,
      your STIHL team

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