Activities Hobbies All About Business-Sized #10 Envelopes Share PINTEREST Email Print Kelvin Murray/Getty Images Hobbies Contests Basics Tips and Tricks Dream Vacations Win Money Win Electronics Home and Garden Lotteries Win Vehicles Jewelry and Clothing Types of Contests Creative Contests Scams Couponing Freebies Frugal Living Fine Arts & Crafts Astrology Card Games & Gambling Cars & Motorcycles Playing Music Learn More By Sandra Grauschopf Sandra Grauschopf Facebook Twitter Writer University of Maryland Sandra Grauschopf has been working in the contests industry since 2002. She is a passionate sweeper, with tens of thousands of dollars worth of prize wins to her name, and she has been sharing advice about how to be a winner for over a decade. Learn about our Editorial Process Updated on 08/30/20 If you're not familiar with what #10 envelopes are, you might know them better as business-sized or standard envelopes. Even if you don't know their name, you'd probably recognize their long, thin shape, and you've surely received them in the mail. What Is a #10 Envelope? #10 envelopes have a standard size of 4 1/8 inches high by 9 1/2 inches long. They're designed to hold a standard 8 1/2 x 11-inch piece of paper folded into three sections, making them practical for office use. They're perfect for sending invoices, checks, official correspondence, and other business letters #10 envelopes and letter-sized envelopes are the most commonly used in America. Letter-sized envelopes are commonly used for informal letters; many stationary sets come with this size envelope. Compared to #10 envelopes, letter-sized envelopes are narrower but broader and closer to square-shaped. Where to Find #10 Envelopes If you're in the United States, #10 envelopes are easy to find. You can buy them directly from the post office, from office supply stores like Staples, from online stores like Amazon, and you can usually find them at any big-box store or major retailer that sells stationary or school supplies. How to Make Your Own #10 Envelopes: Need a #10 envelope in a hurry, and don't want to run out to the store? Or maybe you'd like to save money by turning a regular piece of paper into the envelope you need? As it turns out, you can easily create your own #10 envelope with nothing but a glue stick, a ruler, some scissors, your printer, and this envelope folding tutorial from Instructables. It might take a little practice to get these steps right, but if you need an envelope in a pinch, being able to simply make one yourself comes in handy! Using #10 Envelopes to Enter Sweepstakes: If you want to enter mail-in sweepstakes, #10 envelopes are one of the essential supplies you'll need to have on hand. Many sweepstakes specify in their rules that you'll need to send your entries in a standard business-sized envelope to enter. Be sure to follow the rules carefully, because using the wrong-sized envelope could disqualify you from the sweepstakes and destroy your chances of winning. Many sweepstakes sponsors will disqualify anyone who deviates from their rules, even for something as seemingly-unimportant as the envelope their entry arrives in. How to Save Money While Buying #10 Envelopes Many places sell #10 envelopes, which means that there are plenty of chances to comparison shop for a good deal. Here are some of the places to check to see where you can get the best prices when you're buying business-sized envelopes: Specialist online shops like Envelopes.comLarge online retailers like AmazonBig box retailers like Walmart or KMartOffice supply stores like Staples or Office DepotGrocery and drug storesWarehouse stores like Sams Club or Costco With some luck, you can also find #10s on sale at thrift stores, yard sales, and flea markets which usually offer deep discounts. By shopping around these locations, you can save money buying #10s. Don't forget to use coupons and gift cards to reduce your envelope costs even more, when you have the opportunity.