I want to update the string length for a shapefile layer in QGIS. I've tried opening up Layer Properties and clicking edit but it won't let me change it manually. Also I've tried using the field calculator but I can't seem to get my head around it. I can create a new comment field (see "Comments_1"), but can't update the existing "Comments" to a character length of 254. The screenshot shows both windows I tried in.

enter image description here

  • I might suggest create a new field as you indicated, Output field type=text, Output field length=254 and in the expression section - "Comment". I am not aware how to change those properties in QGIS. I am sure you could do it in Python though.
    – Binx
    Jun 14, 2022 at 18:14
  • There is a deleted answer by @Mayo, propsing to use refactor fields. It is a completele valid solution, I don't know why OP deleted the answer...
    – Babel
    Jun 14, 2022 at 19:46
  • Refactor fields is interesting but require to save the results within a new layer. With the method proposed by Binx, the result can be updated within the same layer.
    – user35117

2 Answers 2


If you want to change the length of a field you need to use the “Refactor fields” tool.

  • Which is under the Processing menu, Toolbox, expand "Vector table" then double-click on "Refactor fields".
    – Malvineous
    Aug 22 at 9:48

As in the comment from Binx, the main bit here is to calculate a new field and use the input boxes to set the field type and length:

enter image description here

Using 'length()' in the expression will return the actual number of characters in x, not reset a field to that length: enter image description here

  • Nice annotations in your image!
    – Binx
    Jun 14, 2022 at 18:53
  • Note: You are limited to 10 characters for your Output field name.
    – Binx
    Jun 14, 2022 at 19:08
  • And the maximum string length in shapefile is just that 254 characters.
    – user30184
    Jun 14, 2022 at 20:36

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