There are a number of easy ways to add calendar to desktop wallpaper. One of them is using an online service like BigHugeLabs Wallpaper. I didn’t find any limitation on how many wallpapers you can add calendar to within the site. After finish with one wallpaper, you can process another one. What you need to do is simply upload the image or pick one from Facebook or Flickr, make some simple adjustments and finally click the Create button to generate and view the result.
There is no information on the size limit of the uploaded image as well, so I presume you can upload image in any size. After selecting the image or wallpaper to be uploaded, you can customize it. The allowed customization includes resizing the image, positioning the calendar within the wallpaper, changing font color, specifying which part of the wallpaper that must stay visible if it must be cropped and applying some effects to the wallpaper.
Clicking the Create button will bring you to a web page where you can view the output. If you think something is missing, you can edit the wallpaper by clicking the edit button. If you’re satisfied, you can download the wallpaper as a JPG file.
Unfortunately, while you can resize the image, you cannot set a custom size for the calendar. There is no preview window, but you can edit the wallpaper as many times as you like. Another missing feature is the lack of the ability to process multiple wallpapers at once.
However, users should admit that BigHugeLabs Wallpaper is easy and fast. It also doesn’t require sign up to use it. It is said that you can save the uploaded images for future use if you create a free account but I didn’t try it.