136 Quick tips for making a small PDF file size

I love PDF. I'm just a total PDF fan boy. But here is one of my pet peeves. Some times PDFs are just done too big. For example, have ever exported a one page PDF, and you get like a 500K file. What the heck? I mean that's not huge, but it's annoying because you know that it should only be like 150K. And if you're emailing it to someone, or putting it on a website for a 1,000 people to download, that could make a big difference. So why are PDFs sometimes much larger than they need to be? Well, let me show you a few things to pay attention to when you're exporting a PDF.

I'm going to go to the file menu and choose export. The first thing you need to do is, decide whether you're going to use the PDF interactive or the PDF print. If your document has buttons or movies or sounds or that kind of thing, then you can go ahead and use interactive. But for virtually all other PDFs, you're going to want to use print. Stuff you're going to send to a client to proof. Or things you're putting on our website for somebody to download and print. Adobe PDF print is the better option. Now the first mistake that a lot of InDesign users make is to choose one of the PDF x presets.

These are great for sending to a printer, but they're not so good at making a really small PDF that you'll email to somebody or put up on website. The second mistake that a lot of InDesign users make, is to jump right down to the smallest file size preset. Smallest file size sounds great, but it usually degrades your PDF too much. It becomes not really useful at all. Images get really icky, and even some text can have problems. That said, smallest file size is a good starting point. So, I usually start there and then make some changes myself.

For example, one change that I almost always make is to turn on create tagged PDF. This option is necessary if you want anybody with a visual disability to read your PDF. But it's also important, if you want people to be able to export the text or even just copy and paste text out of your PDF, which is really helpful for a lot of people. So I like having that on. I also turn on bookmarks and hyperlinks. This way, if I do have any bookmarks and hyperlinks in my document, they're exported, and it doesn't add hardly any space to your file size, so I leave that turned on.

Next, I head over to the compression pane of this dialogue box, and I can see that the compression, is just too low. In fact, it's set to low, image quality low. No wonder the images look so terrible. So, I'm going to set this to medium. Medium is much better. And I'm going to set this both for gray scale and color images. You might want to set it higher, to high or maximum, but honestly, if you're trying to put a PDF on a website for somebody else to print, medium is typically all you really need. The other problem here, is that color images are down sampled far too much.

100 pixels per inch, that is too low. I'm going to increase this to 150 pixels, and I'll make sure that this is set to 150 as well. At 100 pixels or below, your images just get all pixellated and crunchy, so you don't want that. 150 pixels per inch is not only a better resolution, but allows your viewer to zoom in to 200% and still get an adequate representation of an image. I'm going to jump over here to the output pain, and I want to point out one other thing that you might want to change. One of the biggest differences between a really large PDF, and a tiny PDF, is whether or not your profiles are included.

And I don't want to get too technical here, but it all has to do with this color area inside this dialogue box. If you have any CMYK images in your document, or if you're using convert to destination, or convert to destination preserve numbers, and you choose a CMYK destination. Well, your document is going to to be much larger, it's larger because CMYK is larger than RGB. But it's also larger because, the destination profile, the CMYK profile tends to add 400 or 500k to the size of your PDF.

If you're sending a document to a printer, well, maybe you need that, but if you're just putting something on a website, and you want to keep it small, you absolutely do not need that. So I'm going to leave this set to either No Color Conversion, or Convert to Destination and then set destination to an RGB output space. The most typical one you'd want to use is SRGB, this way all your C,Y and K colors are going to be converted to RGB, they'll get brighter, more dynamic, it'll look much better when the person opens it up. Now I don't mind including the destination profile for an RGB, PDF.

Because RGB profiles are really tiny, it only adds maybe one or two k. It's the CMYK profiles that are really huge. Anyway, that's pretty technical, but it's really important that you know CMYK big RGB small. Finally the last thing I'm going to do, is head back to the general pane and turn on view PDF after exporting. Just so that I can see my PDF after it exports it. I like that. Now, I don't want to have to make these changes every time I export a PDF, so I'd better say this is a preset. I'll click the Save Preset button, and then I'm going to name my preset and I'm going to call it Pretty Small PDF.

Click OK. And now that shows up in my PDF preset pop-up menu here and I'll be able to use it from now on. I'll click Export, and InDesign will warn me that the document transparency blend space does not match the destination color space. Once again it has to do with that CMYK versus RGB. I'm going to be pushing all of my CMYK colors, like the images and color swatches into RGB, and InDesign is warning me that that's going to happen. So I'm saying, that's fine, it's okay. I'll click OK, InDesign exports the PDF and opens it in Acrobat.

I'll click the Fit Page in Window button here, and we can see that the image looks really good, bright, and still very small. In fact, let's switch to the desktop and I'll show you that this document is only 130k. I happen to know that this same flyer, if I export it as a PDF X1A, it would be over a megabyte. So by making a few little tweaks, we cut the size of this thing by 90%. Now clearly, this is all about finding the right balance between usability and file size. The more use you want out of it, the bigger the file size.

If you want something, that you can print on a commercial printing press, it's going to be bigger. But, if you're just putting a flier or a form on a website, then using these tricks to cut down the size is just the ticket.