Envelope sizes explained: A4, A5, letter and window envelopes

Envelopes look simple, but buying the wrong size is a common mistake. A letter gets folded too many times, or a certificate gets bent on the way. Here is a simple guide to choosing envelopes for an office, school or shop in Qatar.

Start with what goes inside

Before you buy, ask one question: will the paper be folded or not? A letter can be folded to fit a small envelope. A certificate, a contract or a document with photos should stay flat. That one choice decides the size.

The common sizes

The international standard sizes are DL (110 x 220 mm) for an A4 page folded in three, C5 (162 x 229 mm) for A5, and C4 (229 x 324 mm) for flat A4. Shop names do not always use these codes, so always check the size in millimetres on the product.

Brown or white?

Brown envelopes are strong and practical. Offices use them for internal mail, sending files between departments, keeping receipts, and passing documents to government offices and PROs. They also hide what is inside.

White envelopes look cleaner and more formal. Use them for letters to clients, invitations, salary slips and anything that goes outside the company. If you have printed letterheads, a white envelope matches better.

Window envelopes save time

A window envelope has a clear panel on the front. You print the name and address on the letter itself, fold it, and the address shows through the window. There is no need to write on the envelope. This is great for invoices and statements that go out every month. Do a test fold first to make sure the address sits inside the window.

Tips for neat mail

• Keep a small stock of letter, A5 and A4 envelopes at the reception desk.
• For thick documents, choose a bigger size instead of forcing papers in.
• Use a stamp with your company name on brown envelopes for internal mail. See our company stamp guide.
• Keep important papers in a file until you send them, so corners stay sharp. Our filing guide helps.
• An envelope opener makes daily mail faster and neater than tearing.

Envelopes with your logo

For a professional look, you can have envelopes printed with your company logo and address, to match your letterheads and business cards. Read our letterhead and envelope printing guide to plan it.

How to order envelopes

Browse our full range of envelopes, or go straight to brown envelopes, white envelopes and window envelopes. Not sure which size you need? Send us a photo of your document on WhatsApp and we will help you choose.

Raifa Centre is in Doha, with branches in Barwa Village and Matar Qadeem. We deliver across Qatar and accept cash on delivery.

Cover photo: Envelopes (Unsplash) by Joanna Kosinska joannakosinska, CC0, via Wikimedia Commons.