The filesize limit used to be 150 KB, now for some reason it is only 40 KB.

To make the problem worse:

  • Ads are now bigger (300x250 instead of 220x250, 36% more pixels)
  • High DPI (aka retina) means 4 times more pixels

As a result, even very simple ads miss the 40 KB criteria.
Given that some sites don't even mention High DPI yet, I am pretty sure that this 40 KB requirement is a leftover from ancient times. Could it please be updated? Or if it is genuinely a bandwidth concern, better state it clearly ("even for High DPI").

By the way, I suggest saying "High DPI" instead of "Retina" which is a brand. Written on High DPI Linux laptop. I also suggest implementing srcset or something similar to serve low-resolution images to low resolution displays.

  • 4
    I found tinypng.com which helps reduce the image size. It took i.sstatic.net/pkZZ4.png from 72kb to i.sstatic.net/wLH9N.png which is 19kb. However, noting that this is for a two color image - 40kb is a bit... tight.
    – user213963
    Commented Jan 17, 2016 at 5:21
  • 40 meager kilobytes??? Wow, that's frustrating. At least they don't demand 4, or 40 bytes. Commented Jan 17, 2016 at 15:18
  • 1
    I think 500k is reasonable for an ad image.
    – bjb568
    Commented Jan 17, 2016 at 18:12
  • 6
    @bjb568, 500k is almost double the size of everything else put together on a page like this one (chrome dev tools said 301 kB in a fresh incognito window). I think that's way too much for a single element of non-primary content.
    – otus
    Commented Jan 17, 2016 at 20:20
  • 4
    500k might be a bit overkill. But the good old 150 would already be a good deal. Hell, even 100k gets you farther than this ridiculous 40k. Or just remove the option for double-sized ads if you can't use it for nearly any remotely intriguing ad but only ones where nobody cares about retina resolution anyway. Commented Jan 17, 2016 at 20:31
  • @otus That's because the page is mostly text (and markup). The size of text and images aren't really comparable.
    – bjb568
    Commented Jan 17, 2016 at 20:50
  • @ChristianRau the 'option' for double sized ads was always there. And they can't really 'remove' it. It just happens that the way the page layout scaling works that if you stuff the image in a spot with the appropriate pixel density, it works like it should for retina images.
    – user213963
    Commented Jan 17, 2016 at 20:56
  • @MichaelT Sure, still the option is rather useless if they reduce the filesize to something where you rarely can use it anyway. It's more like a "taunt" than an actual option most of the times. ;-) Commented Jan 17, 2016 at 22:09
  • 3
    Btw, challenge for GraceNote and the other SE types - please try making the i.sstatic.net/Vz5ZZ.png into a 600x500 px image that fits within the size constraints.
    – user213963
    Commented Jan 17, 2016 at 22:18
  • Note that - like all restrictions on community ad images - the 40kb filesize limit is completely ignored.
    – fredley
    Commented Jan 18, 2016 at 8:54
  • @bjb568, it doesn't matter what the size is used on: adding a 500 kB image would more than double the page load times on slow connections (e.g. mobile connections). Most Q&A pages do not contain large images so the 300 kB ought to be representative. Some smaller increase sounds reasonable, however.
    – otus
    Commented Jan 18, 2016 at 9:50
  • 3
    @MichaelT 9kb: i.sstatic.net/ujT8V.png
    – fredley
    Commented Jan 18, 2016 at 9:55
  • @otus That isn't true. The page size is so small it's negligible. Most of the page load time is opening the connection and drawing.
    – bjb568
    Commented Jan 18, 2016 at 11:33

3 Answers 3


We're going to bump the filesize limit back up to 150KB.

Why did we change it in the first place? Back in August last year, I was informed that paid ads on the sites in the network had a limit of only 40KB. That, and also that I forgot to include a bit about 1px borders around white images on... roughly half the ad threads on the network. So new threads that were created after that, we set to 40KB and that was that, and I would just update the remaining threads when the new ad cycle reset in December (rather than have to disqualify a bunch of ads mid-year). For the most part, not many actually ran afoul of this - even the giant bounty ads were sub 40KB.

Then we got the plans to resize the sidebar, which not only meant the ad cycle reset last week rather than last month, but also meant... some issues with sticking with the original plan of only 40KB. As was pointed out.

After a lot of circular walking we've come to the conclusion we all pretty much agree it's a better idea to bump both paid and community advertising up to 150KB. So we're gonna do that.

  • 2
    Thank you for this. It makes life much, much easier.
    – E.P.
    Commented Jan 18, 2016 at 18:30
  • When are the individual Community Promotion Ad questions expected to be updated with the new loosened restrictions? Commented Jan 18, 2016 at 18:39
  • @ChristianRau Later today - I'm trying to find a nice way to do this that doesn't involve me manually updating all 59 threads (I have other updates to make as well), but failing that it'll happen shortly after I deal with other afternoon tasks.
    – Grace Note StaffMod
    Commented Jan 18, 2016 at 18:40
  • 4
    Any chance of allowing JPG images? That would be really helpful. Commented Jan 19, 2016 at 18:35
  • 2
    Or even SVG ? That would also be really helpful. Commented Jan 20, 2016 at 17:11
  • I don't mind changing it on the sites I can update... linking back to this answer as supporting info. Maybe others will be willing to help as well?
    – Catija
    Commented Jan 20, 2016 at 17:39
  • @JonasCz the issue with svg is that it may utilize fonts that not everyone has installed. See if this uses the same font for you as the image I have below.
    – user213963
    Commented Jan 24, 2016 at 17:01
  • @user213963 - in SVGs fonts can be converted to paths/objects/whatever, so then user's won't need the fonts installed. I'm not sure whether imgur supports SVG though...
    – Wilf
    Commented Mar 19, 2016 at 15:06

40kb is tight for a 300x250 px image. It is very tight for a 600x500 px image. Especially when one wants to start getting in a good looking Retina image.

Lets take an image I'm working on.

Retina sized image

This image is 71kb. It appears to be two color image. It isn't. A lower case 'c' in the middle bit actually looks like:

close up of a 'c'

With various tricks and optimizations, I can do things like make this into a .gif which appears to do a better job of compressing the data - it only has 225 for this two color image and the .gif is 35kb. For those of us who haven't pirated purchased a copy of Photoshop, it can be difficult to find the proper set of tools to do exports of images within the size constraints provided.

Furthermore, if you want something to look good on the side bar when one scales the image to a 4x pixel density, it is necessary to have a bit of data in that image. An actual two color image without aliasing the colors (something that Inkscape gives me no control over) would be smaller. It would also look like crap.

Please don't make us make images that look like crap.

  • 2
    Totally agree, this silly limit just drive away people from something that is already not very popular, in my opinion. Commented Jan 17, 2016 at 21:05
  • I managed to get this particular image to 19kB with the first online PNG optimizer in my search results (this is the smaller image). This isn't completely lossless, but it does make PNGs a lot smaller. Commented Jan 17, 2016 at 22:12
  • 1
    @MadScientist Yep - that was from tinypng (I commented on that originally as an option). I want to point out though that this is a rather simple image - the type that optimizers can do quite well. You get to a more complex one like Coffee.SE and it takes it from 58.6kb to 48.1kb with the old size.
    – user213963
    Commented Jan 17, 2016 at 22:15
  • 2
    @ShadowWizard: I think the program is popular but highly suffers from this ambiguity and from the High DPI ambiguity (many uninformed people still downvote High DPI on sight, the platform should display High DPI images at the final intended size). Commented Jan 18, 2016 at 2:43
  • 3
    FWIW GIMP should be able to handle anything you need to do with ads, no Photoshop required.
    – ɥʇǝS
    Commented Jan 19, 2016 at 15:29
  • I'm curious - How can I be a programmer ? I'd love to read your short, comprehensive, and personal summary, could you post a link ? Commented Jan 20, 2016 at 17:15
  • @JonasCz How to be a Programmer: A Short, Comprehensive, and Personal Summary by Robert L Read
    – user213963
    Commented Jan 20, 2016 at 17:21

tl;dr - can you please allow JPG images?

The Problem

PNG is a lossless format. The only way to reduce filesize is to reduce the amount of information in the image by:

  • reducing resolution
  • quantization
  • other destructive editing

GIF suffers from the same problem. Neither is designed for lossy compression of photographs, which unfortunately a lot of the advertisements contained.

The Solution

JPG would alleviate this problem, though not eliminate it completely (the more information you remove, the more obvious the compression becomes). However, it would give us some leverage. If an ad was too large, we could slowly lower quality until:

  • it was within the accepted size
  • quality dropped below the tolerable threshold and the ad would need to be abandoned

The Demonstration

Consider the following PNG image (528.2 KB):

Now consider the following JPG (39.9 KB):

Yes, some of the finer detail was lost but this would probably only be noticeable on Retina displays anyway. The image now fits within the guidelines.

  • Nice ad, consider posting it on gaming?
    – fredley
    Commented Jan 18, 2016 at 8:53
  • jpegs are beautiful and nice and small for many situations. However, the community promo ad page that says it has to be 40kb or smaller also says: "Must be GIF or PNG". I could get mine tiny if I could post the svg that I build from instead.
    – user213963
    Commented Jan 18, 2016 at 13:23
  • 6
    @MichaelT "However, the community promo ad page that says it has to be 40kb or smaller also says: "Must be GIF or PNG" - Is't that exactly the point of this answer anyway, proposing the removal of that restriction that the answer is already aware of? Commented Jan 18, 2016 at 14:25
  • I will admit to misreading this at first glance. Though I now wonder if the "some of the finer detail was lost" - if its worth doing that lossy bit if it doesn't help. Why post something with the higher pixel density if the finer detail was lost and that would only be noticeable on the higher pixel density screens in the first place? Why not just post at the lower pixel density option in the first place? What does one gain when posting a lower quality image at a higher pixel density?
    – user213963
    Commented Jan 18, 2016 at 15:07
  • 1
    @MichaelT Image quality is the product of many many things. Higher resolution, but lossy compression will (for images like this) look much nicer than a lower resolution image doubled in size. Take a look if you don't believe me
    – fredley
    Commented Jan 18, 2016 at 15:48
  • @fredley Lossy is better than interpolated, but when you scale that back to the higher bit density? Is a lossy 600x500 noticeably better than a 300x250 when rendered at 300x250?
    – user213963
    Commented Jan 18, 2016 at 15:52
  • 1
    @MichaelT Yes, especially when all other images on the page are rendered at retina PD.
    – fredley
    Commented Jan 18, 2016 at 15:53

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .