Even before the computer replaced the typewriter as the standard office tool, letter-sized paper has always been the most common document size. The exception to this, of course, is legal documents, including contracts, loan applications and other legal forms. At 8.5 by 14 inches, legal documents are the same width, but they are slightly longer than letter-sized 8.5 by 11 paper.
If your scanner can accommodate legal-sized paper, scanning the document should just be a matter of tweaking its settings. However, if you have a flatbed scanner that is only 11 inches long, you can scan it twice and use a photo editor to splice the document together.
How to Scan Legal-Size Paper
Because legal documents are the same width as letter-sized paper, most scanners can scan them. In most cases, you simply have to put the paper into the scanner and scan it as you would a letter-sized document. The scanner should automatically detect the size of the document and scan it at its full size.
If this doesn't happen using the scanner's default settings, then you can specify the proper setting using the scanner's software on your computer. The steps to do this vary. On some Canon scanners, you can select the "Long Document Mode" in Advanced Settings. On a Brother scanner, look for the "Long Paper" option found in Custom Settings.
If you're scanning legal-size documents on an HP OfficeJet Pro 8600 or most other OfficeJet Pro printers with a scan function, you can use the HP Scan software that came with it to select the document size. Select "Legal" size or select "Entire Scan Area" in the Scan Size menu.
Scanning Legal-Size Paper on a Short Scanner
If your flatbed scanner is too short for a full 14-inch document, you can scan the page twice and then assemble the two images to recreate the original document. For a legal-size document, the easiest way is to scan the top and then the bottom. Most of the text in the middle of the document will overlap, but that's OK.
If you have a lot of documents to scan, then it may be a good idea to invest in a legal-size scanner that can scan the documents in one sweep. Scanning a document twice and reassembling it only takes a few minutes, but if you have hundreds of documents to scan over the course of a year, it will become a very time-consuming process.
Open your scanning software and make sure it's set to export the scans in an image format like JPG rather than PDF. Place the document in the scanner so that the top portion will be fully scanned. Don't worry about the bottom of the document during this pass. Scan the document as normal and save the image. Next, turn the document around and scan it again so you capture the bottom half in a second image file.
How to Reassemble the Scanned Document
Open your favorite image-editing software. Something like Photoshop or GIMP would be perfect, but any software that lets you size, rotate and cut and paste parts of an image will work fine. Create a new blank image file and select the legal-size paper option if it appears. If it doesn't appear, you can set the size yourself as 8.5 by 14 inches, or 2,250 by 3,900 pixels.
Open the first image you scanned, select it (Ctrl+A) and copy it (Ctrl+C). Click on the blank image you just created and paste it into that image (Ctrl+V). Drag the image or use the arrow keys to position it into the top of the canvas. Next, rotate the second image 180 degrees and copy and paste it onto the bottom of the canvas.
Finally, move the bottom image as needed so that it aligns with the top image. If a line appears or if you can't get the letters or images in the document to align perfectly, use the eraser tool to erase the top part of the second image where it overlaps the first. Save the file and export it to a PDF if needed by using the Print to PDF option in the Print menu.