PDF guides5 min read
How to compress a PDF for easier sharing
Make a PDF small enough for email or an upload form while keeping it easy to read.
When a PDF is huge, it's nearly always because of the pictures in it. Text takes up very little room. A hundred pages of plain writing might be a few hundred kilobytes, while one full-page scan at high resolution can be bigger than that on its own.
That's why compression results are all over the place. A scanned document might shrink to a tenth of its size. A text report saved from Word might barely change, because there wasn't much to squeeze out in the first place.
Compressing a PDF mostly means making the images smaller and saving them at lower quality. You can't undo that, so the trick is to use the lightest setting that gets you under your limit, and no stronger.
It helps to know your target before you start. Email usually tops out somewhere around 20 to 25 MB. Government and job websites are often much stricter, at 2 to 5 MB. Once you know the number, you can stop at the first setting that fits.
When you might need this
- An email or upload form won't accept a file that big.
- People on slow connections are waiting a long time to open it.
- You're storing a lot of documents and space is running out.
- You want to send it from your phone without using up your data.
- A shared folder keeps filling up with oversized scans.
How to do it
- Open Compress PDF.
- Add the PDF you want to shrink.
- Choose a compression level. Start with the lightest one.
- Compress the file and check the new size against the limit you need to hit.
- Download it and look at it at 100% zoom. Pay attention to small text inside pictures and screenshots.
- If it's still too big, go back to the original file and try a stronger setting. Don't compress the compressed file again.
Free, with no account. Open it in a new tab and follow along.
Open Compress PDFTips
- Go easy on documents with screenshots. They're full of small text that turns blurry fast.
- Don't keep compressing the same file over and over. Each time loses more detail, and you save less space each time.
- Check the result at 100% zoom. At thumbnail size, every version looks fine.
- For scanned pages, ask whether you needed such a high resolution. Most documents are easy to read at 200 to 300 DPI.
- Deleting pages you don't need often saves more space than compressing harder.
- If the document has to stay sharp, send only the part the other person needs.
Common mistakes
- Compressing a file that's already small and deciding the tool is broken when nothing happens. There was just nothing left to remove.
- Always using the strongest setting, then sending a document where the charts can't be read.
- Compressing a document you're going to print. Images that look fine on screen can look rough on paper.
- Not keeping the original. Without it, there's no going back.
How this compares to Smallpdf, iLovePDF and Adobe
Compression is where the free plans on Smallpdf and iLovePDF get in the way most. The files people need to compress are the big ones, and big files are exactly what the free upload limits turn away.
Adobe's compressor is good, especially on scans, but it uploads your file and steers you toward an Acrobat plan.
Compressing in your browser means none of that applies. We don't set a size limit, and there's no paid plan, no daily count and no account. The catch is that heavy compression of a large file takes real time on your own computer, and a commercial tool may squeeze a bit more out of some complicated scans.
| Criterion | Smallpdf | iLovePDF | Adobe Acrobat online | Easy File Tools |
|---|---|---|---|---|
| Where your file is processed | On their servers, after you upload it | On their servers, after you upload it | In Adobe's cloud, after you upload it | In your browser, on your own device |
| Account or sign-in | Asked for early, and needed once you pass the free allowance | Optional for small jobs, needed for bigger ones | Most online tools need an Adobe ID | Never needed |
| Usage limits | A few free tasks, then an upgrade prompt | Daily task and file limits on the free plan | The free web tools are mostly a preview of the paid plan | No task counters and no daily limits |
| File size ceiling | The free plan limits upload size | The free plan limits upload size | Cloud upload limits apply | We don't set one. Your device's memory is the practical limit |
| Works without a connection | No, their server does the work | No, their server does the work | No, the cloud does the work | Yes for the browser tools, once the page has loaded |
| Cost | Paid subscription for full access | Paid subscription for full access | Paid Acrobat subscription for full access | Free. Every tool is open to everyone |
Other services change their plans and limits often, so treat this as a rough picture and not a price list. Check their websites for the current details.
Frequently asked questions
- Why do some PDFs hardly shrink?
- If a file is mostly text, or it's already been compressed, there's not much left to remove. Nearly all the savings come from images.
- Does compression lower the quality?
- It can. Images are saved at lower quality, so strong settings can make photos and screenshots look blurry. Use the lightest setting that gets you under your limit.
- Can I undo compression?
- No. Once image detail is thrown away, it's gone. That's why you should keep the original.
- My file only got a little smaller. Why?
- It was probably mostly text, or already compressed. There just wasn't much to take out.
- Is compressing twice better than once?
- No. A second pass usually costs more in quality than it saves in size. Go back to the original and use a stronger setting instead.