Quick Picture Tools /  Wallpaper CalendarUpdated in Jan. 2020   (The old version is here.)
Size W:  H:
Load an image from your computer
or
   
Month: Year:  Number of months:
Cell  width:   height:
Entire background color:
Texts  Size:   Sun & Holidays:   Sat:   
  Blur:   Opacity:   Distance:
Background  Opacity:   Rounded Corners (%):
Holidays ( month / day )
曜日   月
Crop area: 
    JPEG quality:

Wallpaper Calendar

The positions of calendars can be changed using mouse-drag.

If the aspect ratio of the loaded image and the wallpaper calendar to be generated are not the same, two edges may be cut off. "Crop area" slider can be used to select those areas.

This tool can generate wallpaper calendar with width and height of up to 8,000 pixels each.

The loaded image will not be sent to the server. The wallpaper calendar will be generated on your computer side.

Use numerals and the forward slash "/" to add holidays to the "Holidays" field, one date per line.
Wallpaper calendar holidays

Click "Generate image" button to download your edited image.

The default download location of most of browser is "Downloads" folder.
You can change the default download location.
You can also set the browser to ask where to save the file before each downloading.
See details

Example
Wallpaper Calendar

Free online tool to add calendars to your picture
Wallpaper Calendar