How To Make Your PDF Files Smaller

Sometimes you need to create PDF documents that are small enough to upload or submit with a size restriction. You can use Preview to compress the images in a PDF file, but you get better results with more control if you work with the images in the original document.

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Video Transcript: Hi, this is Gary with MacMost.com. Let me show you how to make smaller pdf files.
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So let's say you have a document and you create a pdf file from it and you need to submit it online or through some other process for business or for school. The file is big. In this case my example is just 9.5MB. But let's say there's an upload limit of 5MB or something like that. You need to make it smaller. A quick way to do that is to open it up in Preview. Just double click it and it should open up in Preview and then you can go to File, go to Export, and then from there you can choose, under Quartz Filter,  Reduce File Size. Then let's Save this and you could see instead of 9.5MB it's is now only 202KB. That's a dramatic difference. So what changed? 
Well, let's take a look at this pdf document. Let's zoom in here on this image and you can see how high a resolution it is. But if we look in this document here and we zoom in we can see it compressed the image quite a bit. You don't have as much resolution in there now. That is how I got the savings. Almost all the time when a pdf document is really big it is because the image is in it. The text really doesn't take up much space. It's the images. In this case we've got three high resolution images. So it is no surprise that it is almost 10MB in size. By using Preview's Quartz Filter compression we can compress all of the images inside it easily. This creates a smaller file but at lower resolution.
A better way to do it would be to go back to the original source document. So in this case it is Pages. You open it up here in Pages and we can Edit it. Maybe you made your document in Microsoft Word or InDesign or something else. The same rules apply. You can go in and edit the document. Let's make the images inside of it smaller. Now, ideally you want to have all the images from the document somewhere where you can access them. Maybe a folder that you created and you stored all the images there. But if you didn't don't worry about it too much. Because you can go to Format, Image in the right sidebar and you'll see File Info. You'll see the name of the file there with a little icon next to it. You can drag that out to Export the image right from the Pages document to the Finder. So I'm going to do that for each one of these. Let's get this last one. Now I've got each one of these files here exported at full resolution. 
Now let's open up the first one. If I double click it it will open up in Preview. Now in Preview I can go to File, Export and from there I could set the format to JPEG and set the quality to something smaller. The smaller the file size the more compressed it is. It's not going to look as good. But I'm not going to be able to get it down too much smaller. A better way to do it is to first adjust the size to make it appropriate for the document. If I click on i here I can see that this is 4000 pixels across which is great if you want the full resolution image. If you want to print it out on a high resolution printer. But if you're just doing it in a pdf document on a computer screen then it is probably overkill. So you can go to Tools, Adjust Size. Let's adjust the size down. I'm going to set this to inches. Remember the document was just a regular document. So 8½ inches across. With some margins it is about 7½ inches across. The image is stretched all the way across the page. So 7.5. Let's set the width to 7.5 inches. If the image was only using, say, half the width of the page then maybe I could set this to 4 inches. Make it even smaller. Now resolution would be something like 300 pixels for it to look good in printing or if you want to zoom in. But since we want to compress this a lot we want to make some sacrifices here. We're going to set it to a low resolution of 72 pixels. This should still look passable when viewed on a computer screen. But you could see the file size is much smaller. Now from 2.9MB to 87K. All by going to a smaller width and resolution. I'll click OK and you can see how much smaller the file is there. 
Let's go to View Actual Size. So this is at a 100%. It doesn't look that bad. Let's go to File now and export and also select JPEG and set the quality down and let's get the file size to something like 20K. Let's export it out. I'm going to Save it with another name like that. Now we get this file here. If I open it up you can see the quality definitely is worse, going from 80K to 20K definitely took its toll. But perhaps it's fine for what you need. If not you could have gone with something like around 40K and see if that works for you.
Now I'm going to do the same for these two images here. So I've got 3 very compressed versions of the originals here. I can get rid of these guys and I'm just going to use these. Back in Pages I could go to my first image here. Select it and then click Replace. I'm going to select the image there, the compressed one. You can see how the quality goes down right away with the newer image. I'm going to select this one. Replace. Then finally this one and Replace. So now let's export this out. So I'm going to go File, Export to pdf. Now here's the trick. You might think well I can get even more compression by going to Good or Better. But these images are already super compressed. We reduced the size and we compressed the heck out of them using JPEG compression. Anything with Good or Better is just going to try to recompress them and it is actually not going to get anything more out of them. It may even make the file size a little bit bigger trying to do that. Using Best though won't try to recompress them at all. It's going to use them As Is. We already have them optimized so let's select Best here. Now let's Export this out there and let's get info on this. You can see we are now down to 168K. So we did even better. 
One of the best things about this technique is you didn't need to use the same level of compression for each image. So, for instance, maybe you wanted this one being the first image in the document to look better. So instead of going down to 20K maybe we could have gone to 40K. Or maybe instead of 72 pixels per inch and 7.5 inches we could have done 150 pixels or more per inch at 7.5 inches across to make this one higher resolution while still keeping these pretty low resolution. You could play around with each one individually.
The idea is the same no matter which app you're using. Simply use really compressed images instead of the highest resolution ones when you start or replace the ones that you have if you've already created it. It could work that way in Word or InDesign or any app that you are using to build a document. Keep in mind there are also other things you can do in the document. For instance, it really doesn't matter what the size is. If I were to shrink this over here it would look a lot better at a smaller size since there are fewer pixels and its higher compression here. So, you know, having it be like this, if that's fine for your document, might be the better option. As a matter of fact another technique you can use is to simply shrink the dimensions of the image if you are exporting using Best Quality. It's always going to export the image as is. Doesn't matter what size it is on the page. But if you're going to use Good or Better your results are different. So I'm going to set this to Good and then I'm going to Export this and then I'm going to get a document that is 228K. But, if I were to take this image here and shrink it and maybe do the same for these as well, shrink them down to something that is acceptable for whatever your use is. Now when it compresses them it takes this size into account and it will make an image that is appropriate for these dimensions instead of stretching all the way across the page. So I'll export to pdf here. Let's make sure it is set to Good so it is going to compress. Remember Best is not going to compress it at all. Good or Better will. Now let's export this. Then if we look at the size of this document, instead of 228, we get 154 because it is able to do better compression knowing that the size of the image is smaller on the page. 
You also want to think about other kinds of media in your document. For instance if I create a shape and maybe I put a circle in here that is just a solid color but, you know, if I start doing things like making it be an advanced gradient fill like that and I export. Well then that is going to have to be converted to an image in pdf and it is going to take more space. You can see just by adding this in here right now, if I export to pdf and have the image quality set to Best, you could see this document here goes up about 20K in size just for this circle because it has a gradient in it like that. Try to avoid the extraneous use of graphics and shapes and all of that inside your document if getting them under a certain size is a big concern. 
Hope you found this useful. Thanks for watching.

Comments: 5 Responses to “How To Make Your PDF Files Smaller”

Anthony

2 years ago

Exactly what I’ve been looking to do without success for over a month - needing to send pics and correct plat dimensions to a govt agency for tax reduction purposes. Of course file size w pics must be relatively small. Thank you for the problem solving once again.

Liz

Great tips - have you any advice for reducing size of scanned images. I tried this on a scanned pdf black and white document but most of the text became very fuzzy. Original file size is 58 mb (44 pages). Thanks in advance. There are diagrams in the text but only one picture as such on the front.

Gary Rosenzweig

Liz: Scan images to jpeg, not PDF. A PDF would just be a blank document with the jpeg in it. Better to just have the jpeg and skip the PDF "enclosure." Then the size depends on the jpeg quality and pixels-per-inch you choose. Experiment to see what works best for you.

dailytut

I never thought its possible to compress PDF files. Images and videos are different, but PDF compression going to help me save ton of space in my computer.

Thank you Gary.

Robin.

theresa

1 year ago

Very helpful, thank you!

Comments Closed.

How To Make Your PDF Files Smaller

Comments: 5 Responses to “How To Make Your PDF Files Smaller”

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