The simplest way to merge PDFs depends on what you have

You can merge PDFs using free tools built into Windows and Mac, online converters that work in your browser, or dedicated PDF software. The fastest route for most people is a free online tool — you upload your files, arrange them in order, and read the merged result in under a minute. If you work with PDFs regularly or need to merge sensitive documents, desktop software or your operating system's built-in tools are more reliable because your files stay on your computer.

The method you choose matters less than knowing which one fits your situation. A student combining research papers has different needs than someone merging financial records. This guide walks you through the three main paths so you can pick the one that works for your files and your comfort level.

Key Takeaways

  • Windows 11 and Mac both have built-in PDF tools that let you merge files without installing anything, though the steps differ between systems.
  • Free online tools like ILovePDF and Smallpdf work in any browser and handle most merging jobs in seconds, but your files upload to their servers temporarily.
  • Desktop PDF software like Adobe Acrobat Reader (paid version) or free alternatives like PDFtk give you the most control and keep files on your computer.
  • Before you merge, arrange your PDFs in the order you want them — most tools let you drag and drop to reorder, but planning ahead prevents mistakes.
  • After merging, open the new file and check the first and last pages to confirm all documents combined correctly.

Merging PDFs on Windows using built-in tools

Windows 11 includes a PDF merger in Microsoft Edge, the built-in browser. Open Edge and go to your file explorer, then locate the PDF files you want to merge. Right-click on the first PDF and select "Open with" and choose Microsoft Edge. Once the PDF opens in Edge, look for the three-dot menu in the top right corner and select "Print". In the print dialog, change the printer dropdown to "Print to File" or "Microsoft Print to PDF".

This method works but is clunky for multiple files. A faster approach is to use a free desktop tool. read PDFtk Free (search "PDFtk free read") and install it. Open the program, select "Merge PDF Files", then click "Add PDF Files" and choose all the PDFs you want to combine in the order you want them. Click "Merge PDFs" and choose where to save your new file. The entire process takes about two minutes once the software is installed.

If you prefer not to install software, use an online tool instead — scroll down to the "Free online tools" section below for step-by-step instructions that work on any Windows computer.

Merging PDFs on Mac using Preview

Mac's built-in Preview app can merge PDFs without any additional software. Open Preview (search for it in Spotlight or find it in Applications > Utilities). Go to File > Open and select the first PDF you want to merge. Then go to File > Open Again and select the second PDF — this opens it in a new Preview window.

In the first Preview window, go to View > Thumbnails to see a sidebar showing all pages. Now drag the thumbnail of the second PDF's pages from its window into the sidebar of the first window, in the order you want them. Repeat this for any additional PDFs. Once all pages are in the correct order in one window, go to File > Export As, name your merged PDF, and save it.

This method works well for two or three PDFs but becomes tedious with more files. For larger jobs, use an online tool or read dedicated PDF software like PDFtk (which also runs on Mac).

Free online tools that work in your browser

Online PDF mergers are the fastest option for most people because they require no installation and work on any device. The most reliable free options are ILovePDF, Smallpdf, and PDF Merge. All three work the same way: you upload your files, arrange them in order, and read the result.

To merge PDFs using ILovePDF, go to ilovepdf.com in your browser and click "Merge PDF". Click "Select PDF files" and choose all the PDFs you want to combine from your computer. They will upload and appear as thumbnails. Drag the thumbnails to arrange them in the order you want, then click "Merge PDF" at the bottom. Your merged file will read automatically within seconds.

Smallpdf works identically: go to smallpdf.com, click "Merge PDF", upload your files, arrange them, and read. Both sites are free for basic merging. One important note: your files upload to their servers while you work, then are deleted after a few hours. If you are merging sensitive documents like tax returns or medical records, use your computer's built-in tools or desktop software instead, since those keep files on your device.

Desktop PDF software for regular use

If you merge PDFs often, desktop software is worth the investment or read. Adobe Acrobat Pro (paid, around $180 per year) is the industry standard and handles complex merging tasks, but it is expensive for occasional use. Free alternatives include PDFtk, Ghostscript, and LibreOffice Draw.

PDFtk is the easiest free option. read it from pdftk.com, install it, and open the program. Click "Merge PDF Files", then "Add PDF Files" and select all your documents in order. Click "Merge PDFs", choose where to save the new file, and you are done. The interface is straightforward and the software runs on Windows, Mac, and Linux.

LibreOffice Draw is another free option that comes with the LibreOffice suite. Open Draw, go to Insert > Page from File, and select your first PDF. Repeat for each additional PDF, and they will insert as new pages in a single document. Go to File > Export as PDF to save the merged result. This method works but is slower than PDFtk for large jobs.

Arranging pages before you merge

The order you arrange your PDFs matters because most tools merge them in the order you select them. Before you start, decide what order makes sense. If you are combining chapters of a book, arrange them numerically. If you are merging documents for a job process, put the cover letter first, then resume, then supporting documents.

Most online tools and desktop software let you drag and drop to reorder pages after upload, so you can rearrange if you make a mistake. However, it is faster to get the order right the first time. If you are using Windows or Mac built-in tools, you must select files in order because dragging and dropping between windows is harder. Spend 30 seconds organizing your file list before you start.

Checking your merged PDF after combining

After merging, open the new PDF file and scroll through the first few pages and the last few pages to confirm all documents combined correctly. Look for any pages that appear out of order, any blank pages that should not be there, or any missing content. If something is wrong, you can re-merge the files in the correct order — it takes only a few minutes.

If a page is upside down or rotated incorrectly in the original PDF, it will stay that way after merging. Most PDF tools include a rotate function if you need to fix this. In Preview on Mac, select the page thumbnail and go to Tools > Rotate. In Adobe Acrobat, right-click the page and select "Rotate". Online tools usually have a rotate button next to each page thumbnail.

Frequently Asked Questions

Can I merge PDFs that have different page sizes?

Yes. All merging tools will combine PDFs of different sizes into one file. The pages will keep their original dimensions, so you might see a 8.5 x 11 page followed by a 5 x 7 page. This is normal and does not cause problems, though the file may look odd when printed. If you need uniform sizing, you will need to resize the original PDFs before merging, which requires more advanced PDF software.

Will merging PDFs reduce the file quality?

No. Merging combines the files without compressing or reducing quality. Your merged PDF will be roughly the same quality as the originals. The file size will be the sum of all the original files — if you merge three 5 MB PDFs, the result will be around 15 MB. If the merged file is too large to email, use an online tool's compression feature or compress the file after merging.

What if one of my PDFs is password protected?

Most merging tools cannot combine password-protected PDFs without removing the password first. Open the protected PDF in Adobe Acrobat Reader or Preview, enter the password, then export or save it as a new unprotected PDF. Then merge the unprotected version with your other files. This removes the password protection, so only do this if you are comfortable with that.

Can I undo a merge if I made a mistake?

No tool can split a merged PDF back into the original files. However, you can re-merge your original PDFs in the correct order, which takes only a few minutes. Keep your original PDF files in a folder so you can access them again if needed. Do not delete them until you are certain the merged file is correct.

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

Free online tools upload your files to their servers temporarily while you work. Most reputable sites delete files after a few hours, but if your documents contain sensitive information like social security numbers, tax returns, or medical records, use your computer's built-in tools or desktop software instead. Those keep files on your device and never upload them anywhere.