The most common paper size in the US is 8.5 by 11 inches
When you buy a ream of printer paper at any office supply store, you are almost certainly getting sheets that measure 8.5 inches wide by 11 inches tall. This is called letter size, and it is the default for printers, copiers, and most documents in North America. If you hold a standard sheet of paper in front of you right now, those are the dimensions you are holding.
The next size up, called legal size, is 8.5 inches wide by 14 inches tall — three inches longer. Legal pads use this size, and some printers can handle it, but you have to tell the printer to expect legal paper or it will try to print letter-sized documents and cut them off. Most home and office printers default to letter and do not have a legal tray built in.
Outside the US and Canada, most of the world uses A4 paper, which measures 210 by 297 millimeters (about 8.27 by 11.7 inches). It is slightly narrower and slightly taller than letter size. If you are ordering paper from an international supplier or your printer came from Europe or Asia, check which standard it expects — the difference is small enough that letter paper will sometimes jam in an A4 printer, or A4 paper will not fill an 8.5-inch-wide tray.
Key Takeaways
- Letter size (8.5 by 11 inches) is the standard for US printers and documents, and it is what comes in most reams of copy paper.
- Legal size (8.5 by 14 inches) is three inches longer and is used for contracts and legal documents, but most printers cannot handle it without a special tray.
- A4 paper (210 by 297 millimeters) is the international standard used everywhere except North America, and it is slightly different from letter size.
- Tabloid and ledger paper (11 by 17 inches) are double the width of letter paper and are used for large spreadsheets, posters, and blueprints.
- Your printer's manual or settings menu will tell you which paper sizes it can handle, and using the wrong size can cause jams or cut-off text.
Larger paper sizes for spreadsheets and posters
Tabloid and ledger paper are the same size — 11 by 17 inches — but the names refer to how you orient them. Tabloid is 11 inches wide by 17 inches tall (portrait orientation), and ledger is 17 inches wide by 11 inches tall (landscape orientation). These are exactly double the width of letter paper, which makes them useful for printing large spreadsheets, calendars, or posters without shrinking the text down to unreadable size.
Not all printers can handle tabloid or ledger paper. Most home printers max out at letter or legal size. If you need to print something larger, you will either need a printer with a wider feed tray (common in offices and print shops) or you will need to take your file to a print shop and have them run it on their equipment. A print shop can also handle sizes like 11 by 14 inches or custom dimensions if you need something in between.
How paper sizes relate to each other
The A-series paper sizes (A4, A3, A2, and so on) follow a mathematical rule: each size is exactly half the area of the one before it. A3 is double the size of A4. A2 is double the size of A3. This makes it easy to scale documents up or down without changing the proportions — if you enlarge an A4 document to A3, it will look exactly the same, just bigger.
Letter and legal sizes do not follow this rule. Legal is only 27 percent taller than letter, not double. This is why the A-series is preferred in countries that use metric measurements — it is mathematically cleaner. However, the US adopted letter size before the metric system became standard, and it has stuck around for over a century.
If you are printing a document designed for A4 paper on a letter-size printer, the text and images will usually fit, but the margins will be slightly different. The opposite is also true — letter-sized documents print on A4 with slightly different margins. For most everyday documents, this difference is not noticeable. For precise layouts like business cards or brochures, you need to know which size you are designing for.
What "weight" means on a ream of paper
When you buy paper, the package often says something like "20 lb bond" or "24 lb text." This number refers to the weight of a ream — 500 sheets — of that paper at its standard size. For letter-size paper, 20 lb means 500 sheets weigh 20 pounds. For A4 paper, the weight is measured differently, using grams per square meter (gsm).
Standard copy paper is usually 20 lb bond, which feels thin and light. Cardstock or heavier paper might be 65 lb or 110 lb, and it feels noticeably thicker and stiffer. If you are printing photos or documents you want to last, heavier paper looks and feels more professional. If you are just printing everyday documents, 20 lb is fine and is also the cheapest option.
The weight system is confusing because it does not directly tell you how thick the paper is — a sheet of 20 lb bond is not one-fifth the thickness of 100 lb cardstock. The weight is about density and fiber content, not just thickness. If you need paper for a specific purpose, the best approach is to look at the thickness measurement in millimeters (called the caliper) or to feel the paper in person before buying a whole ream.
Specialty paper sizes you might encounter
Index cards come in 3 by 5 inches and 5 by 8 inches. These are small enough to hold in your hand and are used for note-taking, flashcards, and filing systems. Most printers cannot print on index cards directly — you have to buy pre-printed cards or print on regular paper and cut it down.
Envelopes have their own sizing system. A standard business envelope (called a #10 envelope) is 4.125 by 9.5 inches. Some printers have an envelope tray, but many do not. If your printer can handle envelopes, the manual will tell you which sizes it supports.
Postcards are typically 4 by 6 inches or 5 by 7 inches. Some printers can print postcards directly if you feed them through the manual tray. Larger postcards or custom sizes usually require a print shop.
How to check what your printer can handle
The easiest way to find out what paper sizes your printer supports is to open the printer settings on your computer. On Windows, go to Settings, then Devices, then Printers and Scanners, find your printer, and click it. On a Mac, go to System Preferences, then Printers and Scanners, select your printer, and click Options and Supplies. The specifications will list the paper sizes the printer can feed.
You can also check the printer's manual or the manufacturer's website. Search for your printer model number plus "specifications" and look for a section called "Paper Sizes" or "Media Support." The manual will also tell you the maximum paper weight the printer can handle, which matters if you are using cardstock or specialty paper.
If you are not sure whether a particular sheet will fit, measure it and compare it to the sizes your printer supports. If it is wider than your printer's maximum width, it will jam. If it is longer than the maximum length, it will either jam or the printer will cut it off mid-print.
Frequently Asked Questions
What is the difference between letter and A4 paper?
Letter is 8.5 by 11 inches and is the North American standard. A4 is 210 by 297 millimeters (about 8.27 by 11.7 inches) and is used everywhere else. A4 is slightly narrower and slightly taller. Most printers can handle both, but you have to tell the printer which one you are using or it will try to print the wrong size.
Can I print legal-size documents on a letter-size printer?
No. Legal paper is 14 inches long, and most home printers only accept paper up to 11 inches long. If you try to feed legal paper into a letter-size printer, it will jam. You need a printer with a legal tray, or you need to take the document to a print shop.
Why does my printer say it supports A4 but I only have letter paper?
Your printer can handle both sizes. Letter and A4 are close enough that most modern printers accept either one. Just load the paper you have and tell the printer in the print settings which size it is. The margins might be slightly different, but the document will print.
What does "20 lb paper" actually mean?
It means 500 sheets of that paper at its standard size weigh 20 pounds. Standard copy paper is 20 lb, which is thin and light. Heavier paper (like 24 lb or 32 lb) is thicker and feels more substantial. The weight does not directly tell you thickness — use the caliper measurement in millimeters if you need to know exactly how thick the paper is.
Can I cut letter paper to make it A4 size?
Technically yes, but it is not practical. A4 is 8.27 inches wide, and letter is 8.5 inches wide, so you would only need to trim 0.23 inches off the side. However, cutting paper by hand is not precise enough for a printer, and the edges will be rough. If you need A4 paper regularly, just buy a ream of A4 instead.