Preferences > Map Settings


Settings for the map projection and data interpretation

Map Projection

On each startup JOSM sets the projection method, the coordinate display format and the system of measurement back to user default settings.

Projection method

For the current session the projection method can be changed here.
A list of common projections is offered and customs projections can be set.

Projection code
shows the EPSG code for the projection.
shows the region where the projection is valid.
Some projections are valid only for small parts of the world.

Common default projection for JOSM is Mercator (EPSG:3857).
It has certain advantages, one of them is that geometric figures (e.g. circles and rectangles) aren't deformed when displayed.
JOSM reprojects raster images from the projection of the source automatically to the current projection method.

Set as default
With this button the user default setting for the projection method is set. It is visible in Expert mode only, #14877.

Display coordinates as

Set the user default coordinate format (Decimal, Degrees, Nautical or Projected Coordinates).

System of measurement

Set the user default system of measurement (Metric, Chinese, Imperial or Nautical Mile).

In the status bar the coordinate format and the system of measurement can be changed in the context menu for the current session. So the numbers in Bounds may not fit to Display coordinates as.

Map Paint Styles

In this tab the styles for displaying the data can be changed. Beside the internal styles also externals styles are presented and can be activated.


See Styles and Map Styles panel.

Tagging Presets

If you want to learn how presets can also be added to the toolbar see - Toolbar Customization
If you want to use presets or need complete reference of presets see Presets

Presets allow you to select predefined tags for objects. From this area of the preferences menu you can choose which presets to use.

The preset list will be downloaded automatically, then you have two options:

Activate preset(s) from available presets

Use source:trunk/resources/images/preferences/activate-right.svg the blue, right arrow in the middle.
Items on the right will appear in Presets menu.

Add a preset from the file

Include one from a URL or local file (or network-located file or file in a Dropbox alternative) by clicking on the source:trunk/resources/images/dialogs/add.svg plus button on the right.

Adding presets requires a restart of JOSM. Then the tagging presets can be selected as usual.

File Backup

file backup screenshot


  • Auto save enable: enable or disable autosave altogether (autosave.enabled)
    • Auto save interval: set a custom value for the time interval in seconds (default is 300) (autosave.interval).
    • Auto save files per layer: set a custom value for the number of backup files per data layer (default is 1) (autosave.filesPerLayer).
      If you increase it to 2, JOSM will not only save the last snapshot of your changes, but also the last but one (in case it differs from the last, otherwise an even older snapshot, if available).


  • Keep backup files when saving data layers: enable or disable file backup of data files (save.keepbackup)
    If you save a data layer to a local file and the file already exists JOSM writes the data to a temporary file (with a tilde ~ as suffix). It then copies the temporary file to the target file.
    Here you can specify whether JOSM should delete the temporary file or whether it should leave it as "backup" in the file system.


  • Notification at each save: choose if you want to see a small notification at each save (autosave.notification).

Back to Preferences dialog
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Last modified 2 months ago Last modified on 2020-11-08T16:14:11+01:00

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