The fastest way to merge documents into one PDF

The method you use depends on what documents you're starting with and what device you have. If you're on Windows or Mac and your documents are already PDFs, the built-in Preview app (Mac) or Microsoft Edge (Windows) can combine them in minutes without installing anything. If your documents are Word files, Excel sheets, or images, you'll need either a free online tool or a PDF program that can import multiple file types.

The most common situation is combining several PDFs into one. On a Mac, you open them all in Preview, drag them into the sidebar in the order you want, then export as a single PDF. On Windows, you open them in Edge, use the print function to save them together, or use a free tool like ILovePDF or Smallpdf. If your documents are mixed formats — some PDFs, some Word files, some images — an online tool usually works faster than trying to convert everything first.

Key Takeaways

  • Mac users can merge PDFs directly in Preview by opening all files, arranging them in the sidebar, and exporting as one PDF without any additional software.
  • Windows users can combine PDFs using Microsoft Edge's print-to-PDF feature or free online tools like ILovePDF, which also handle mixed file formats.
  • If your documents are Word files, images, or other formats, converting them to PDF first or using an online merger tool is faster than merging them one at a time.
  • Online PDF tools are free and work on any device, but they upload your files to the internet — check the privacy policy if your documents contain sensitive information.

Merging PDFs on a Mac using Preview

Preview is built into every Mac and can combine PDFs without opening a web browser or installing anything. Open the first PDF in Preview, then go to File and select Open. Hold down Command and click each additional PDF you want to merge — they'll all open in the same Preview window. In the sidebar on the left, you'll see thumbnails of every page from every document stacked together.

Drag the thumbnails to reorder them however you want. Pages from different PDFs can be mixed together, or you can keep them grouped by document. Once the order is correct, go to File, then Export As. Choose PDF from the format dropdown, name your merged file, and click Save. The new PDF will contain every page in the order you arranged them.

If the sidebar isn't visible, go to View and click Thumbnails. If you want to remove a page before merging, right-click the thumbnail and select Delete.

Merging PDFs on Windows using Microsoft Edge

Windows 10 and 11 come with Microsoft Edge, which can print multiple PDFs into a single file. Open the first PDF in Edge, then go to File and Print (or press Ctrl+P). In the printer dropdown, select Print to PDF. Before you click Print, open a second tab and repeat this for each PDF you want to merge — don't click Print yet on any of them.

This method works best if you have only two or three PDFs. Open the first PDF, print it to PDF and save it with a temporary name like "part1.pdf". Then open the second PDF, print it to PDF, and save it as "part2.pdf". Once you have all the individual PDFs saved, use a free online tool (see the section below) to combine them in the correct order.

If you have many PDFs to merge, the online tool method is faster because you can upload them all at once and arrange them in one step.

Using a free online PDF merger tool

Online tools like ILovePDF, Smallpdf, and PDF Merge work on any device and handle mixed file types — you can upload PDFs, Word documents, images, and Excel files all at once. Go to the tool's website, click the upload button, and select all the files you want to combine. They'll appear as a list that you can drag to reorder.

Once the order is correct, click Merge or Combine (the button name varies by tool). The tool will process your files and let you download the merged PDF. The whole process usually takes less than a minute. Most of these tools are free for files under 50 MB, though some limit how many files you can merge at once.

One important thing to know: your files are uploaded to the tool's servers while they're being processed. If your documents contain sensitive information like medical records, financial statements, or passwords, check the tool's privacy policy first. Many reputable tools delete files automatically after a few hours, but it's worth confirming before you upload.

Converting Word documents and images to PDF before merging

If most of your documents are Word files or images, you have two options: convert them to PDF first, then merge them, or use an online tool that accepts mixed formats. Converting first gives you more control over how each page looks.

To convert a Word document to PDF on Windows, open the file in Microsoft Word, go to File, then Save As. In the format dropdown, select PDF and click Save. On a Mac, open the document in Word, go to File, then Export As, select PDF, and click Save. For images, right-click the image file, select Open With, and choose Preview (Mac) or Photos (Windows). Then go to File and Export As PDF.

Once everything is in PDF format, use the Preview method (Mac) or an online tool to merge them all together. This approach takes a few extra steps but ensures that fonts, formatting, and image quality stay consistent in the final merged file.

Arranging pages in the correct order

Before you merge, decide what order the documents should appear in. Write down the filenames in the order you want them — for example, "cover.pdf, chapter1.pdf, chapter2.pdf, appendix.pdf". This prevents mistakes and saves time when you're uploading or arranging files.

If you're using Preview on a Mac, you can see all the page thumbnails at once and drag them around until the order is right. With an online tool, you usually see a list of files with up and down arrows to move them. Some tools let you drag files to reorder them, which is faster if you have many documents.

If you realize after merging that the pages are in the wrong order, you'll need to merge again — most tools don't let you edit the merged file. That's why checking the order before you click Merge saves time.

Handling large files and file size limits

Most free online tools limit merged files to 50 MB to 100 MB total. If your documents are larger, you have a few options: merge them in smaller batches, use a paid version of the tool, or use the built-in Preview (Mac) or Edge (Windows) methods, which don't have file size limits.

If you're merging many large PDFs, Preview on Mac is usually the fastest because everything happens on your computer without uploading to the internet. On Windows, if you have a lot of files, consider using a desktop PDF program like Adobe Acrobat Reader (paid) or Foxit Reader (free version available), which can merge files locally without file size restrictions.

Before you start, check the total size of all your files. On Windows, select all the files, right-click, and look at Properties to see the combined size. On Mac, select all the files in Finder, then press Command+I to see the total size. This tells you whether an online tool will work or whether you need a local method.

Frequently Asked Questions

Can I merge PDFs on my phone or tablet?

Yes, but it's slower than on a computer. On iPhone or iPad, use an app like PDF Merger or Documents by Readdle, which let you import PDFs and combine them. On Android, try PDF Merge or similar apps from the Google Play Store. Most of these apps are free but may have limits on file size or the number of documents you can merge at once.

What if I want to delete some pages before merging?

In Preview on Mac, right-click the page thumbnail and select Delete before you export. With an online tool, most don't let you delete individual pages — you'd need to remove them from the source PDF first using Preview, Edge, or a dedicated PDF editor. Then merge the cleaned-up files together.

Does merging PDFs change the quality or file size?

Merging doesn't reduce quality — the pages stay exactly as they were in the original files. File size usually stays about the same or increases slightly because you're combining multiple files into one. If the merged file is much larger than expected, the original PDFs may contain high-resolution images or uncompressed content.

Can I merge PDFs that have different page sizes?

Yes. Preview on Mac and most online tools will combine PDFs with different page sizes without any problem — each page keeps its original size. The merged file will just have pages of varying dimensions, which is fine for most uses. If you need all pages to be the same size, you'd need to resize them first using a dedicated PDF editor.

Is it safe to use online PDF merger tools with confidential documents?

Most reputable tools delete files automatically after processing, but there's always some risk when uploading to the internet. If your documents contain passwords, medical information, or financial data, use Preview on Mac or a desktop program on Windows instead. These methods keep everything on your computer and never upload anything to the internet.