Big water marks - Forums

Ultrawide	16:9	16:10	4:3	5:4
2560 × 1080	1280 × 720	1280 × 800	1280 × 960	1280 × 1024
3440 × 1440	1600 × 900	1600 × 1000	1600 × 1200	1600 × 1280
3840 × 1600	1920 × 1080	1920 × 1200	1920 × 1440	1920 × 1536
	2560 × 1440	2560 × 1600	2560 × 1920	2560 × 2048
	3840 × 2160	3840 × 2400	3840 × 2880	3840 × 3072

Wide	Ultrawide	Portrait	Square
All Wide	All Portrait
16 × 9	21 × 9	9 × 16	1 × 1
16 × 10	32 × 9	10 × 16	3 × 2
	48 × 9	9 × 18	4 × 3
			5 × 4

Gandalf – 8 years ago8230

It depends on several factors, not just size. The rule is a bit vague because watermarks can be hard to describe and we want to leave some room for common sense.

Anything that covers up a significant amount of the picture is too big. (yes that is still vague)
Positioning matters. A watermark in the corner is less obtrusive than one in the center of the image.
It is important what is covered. A watermark that only covers background is less obtrusive than a watermark that covers the primary focus.
Colors and opacity are also a factor. A screaming red name in bold letters is more noticeable than a soft tone that integrates with the background.

Those aspects concern the visual appearance. Another matter to consider is the function of a watermark.

Some watermarks are specifically design to make a picture "unusable" to protect copyright. Stock sites usually plaster their watermark at low opacity across the entire image. DeviantArt also offers artists to put a big logo in the center. Obviously we will delete pictures like that.
Plain URLs are almost never okay. There are some edge cases, for example some wallpaper hosters like to put their URL in the corner, usually making it obvious that they do not intend to declare ownership. Whenever possible we will prefer the original without that URL but if there is no other version available and the wallpaper is of high quality we sometimes opt to keep it until an "untainted" version arrives.
Many not-so-skilled artists like to put their own name or URL on other people's work while hardly changing anything else. That's obviously not okay.

Also, not every text or logo inside a picture is automatically a watermark:

Many artists like to leave a small signature. This is usually integrated into the picture in a subtle way and can even be considered part of the picture as a whole. Signatures like that are fine. In fact if someone uploads a wallpaper where the artist's signature has obviously been removed we will instead keep the original.
Some wallpapers are simply a logo on a background. Generally if the logo is something well known and the quality is good we will accept it. If someone uploads their own logo it will be judged more harshly (see uploading your own creations). If someone slaps their own name in flat bold letters on an existing wallpaper to promote their website or youtube channel we will delete it.

The point is, watermarks are hard to judge. What FuriouZ posted is a good example. The watermark is very noticeable and probably will prevent a lot of people from considering it a valid wallpaper. However it's also in the corner and appears to be legit (i.e. by the original creator). Additionally on many monitors it won't even be visible at all due to the aspect ratio (the picture is a little more square than the common 16:9).

I'm sorry I can't give you a more definitive answer. Maybe someone else has better words for it.