
If you're sending a letter, you'll want to choose an envelope that fits it perfectly. The standard letter size in the US is 8.5 x 11 inches.
You can choose from several envelope sizes that accommodate this size, including No. 9, A2, and A6 envelopes. The No. 9 envelope is the most common choice for standard letter mail.
The No. 9 envelope measures 3.875 x 6.5 inches, which is slightly smaller than the standard letter size, but it still fits a standard letter with a bit of extra room. This is a good option if you want to add a bit of padding to your letter.
A2 envelopes, on the other hand, are slightly larger, measuring 4.5 x 6.25 inches.
Common Envelope Sizes
Letter-sized envelopes are typically 8.5 x 11 inches, which is the standard size for most business correspondence.
This size is suitable for standard A4 paper.
Common envelope sizes include A2, A6, and C5, which are used for various purposes, including business and personal correspondence.
Take a look at this: Business Envelope Sizes
#10 (4.125" x 9.5")
The #10 envelope is a popular choice for business and professional correspondence. It measures 4.125 inches in height and 9.5 inches in width.
This envelope size is commonly paired with a tri-fold letter, making it a convenient option for sending documents. The #10 envelope is also a popular choice for traditional and direct mail.
The maximum enclosure size for the #10 envelope is 3.875 inches in height and 9.25 inches in width. This means you can safely insert documents of this size without them sticking out of the envelope.
The #10 envelope has a V-shaped flap that is 1.875 inches high at the V point and 9.5 inches wide. The flap is located along the width (long end) of the envelope.
Here's a quick summary of the #10 envelope dimensions:
- Inches: 4.125 x 9.5
- Centimeters: 10.48 x 24.13
- Millimeters: 105 x 241
Large Dimensions
Large envelopes can be quite varied in size, but in the US Postal Service's classification, they're often referred to as "flats." Flats include large envelopes, newsletters, and magazines.
A unique perspective: Pre Paid Postage Envelopes
In the US, a large envelope typically measures 9 x 12 inches.
If you're working with international measurements, a large envelope is equivalent to 22.86 x 30.48 centimeters.
For precision, the dimensions in millimeters are 229 x 305.
Here's a quick reference guide to help you remember the dimensions:
- 9 x 12 inches (US)
- 22.86 x 30.48 centimeters (international)
- 229 x 305 millimeters (precision)
Standard Letter Size Dimensions
Standard Letter Size Dimensions are perfect for standard letters. Letter size envelopes measure 3.5 inches by 5.5 inches. This is the standard size for a letter, and it's ideal for sending mail to friends, family, or businesses.
You can fit a standard letter in a letter size envelope, and it's a great size for sending documents, checks, or other small items. Letter size envelopes are also commonly used for direct mail campaigns and marketing materials.
Letter Size Dimensions
Letter size envelopes are a staple for sending standard letters and measuring a specific size. They typically measure 3.5 to 4.5 inches in length.
The width of a letter size envelope is usually around 6.5 to 7.5 inches. This allows for a standard letter to fit comfortably inside.
You can fit a standard letter inside a letter size envelope, which is usually around 6.5 to 7.5 inches in width.
For your interest: Standard Record Cover Size
Number 10 Dimensions

The #10 envelope is a standard size you'll often see in business correspondence. It's a staple in the professional world, and for good reason.
The dimensions of a #10 envelope are 4.125 x 9.5 inches. You can also measure it in centimeters (10.48 x 24.13) or millimeters (105 x 241).
These dimensions are standard, so you know exactly what to expect.
International Envelope Sizes
International Envelope Sizes offer a variety of options for letter-sized rebates, with the most common being the C5 envelope, which measures 114 x 162 mm.
In Asia, the C6 envelope is widely used, measuring 114 x 162 mm, similar to the C5 envelope.
The C5 envelope is also used in Europe, where it's a standard size for business and personal correspondence.
9x8.875
The 9x8.875 envelope size is a popular choice for businesses that require a return envelope. It's often used by banks, insurance agencies, and credit card companies.
This size envelope is perfect for fitting inside a #10 envelope, making it a great option for businesses that need to send a reply mail. It's also known as a Courtesy Reply Mail (CRM) or Business Reply Mail (BRM).
The dimensions of a #9 envelope are 3.875 inches by 8.875 inches. This size is ideal for standard letters and is a great choice for businesses that need a professional-looking envelope.
Here are the key facts about the 9x8.875 envelope size:
- Dimensions: 3.875 x 8.875 inches
- Commonly used by businesses for return envelopes
- Also known as #9 envelopes, CRM, or BRM
A6 Dimensions
The A6 envelope is a popular choice for small-sized cards, invitations, and correspondence. It's a versatile size that's widely used.
The A6 envelope measures 4.75 x 6.5 inches. This is the standard size for this type of envelope.
If you need to know the dimensions in centimeters, the A6 envelope measures 12.07 x 16.51 centimeters. That's a bit longer and wider than the inch measurement.
For those who work with millimeters, the A6 envelope is 121 x 165 millimeters. This is a useful measurement if you're working with precise dimensions.
Here are the A6 envelope dimensions in different units:
I2 Dimensions
I2 Dimensions are a specific size used by many companies and organizations. They can be a bit tricky to find, but standard dimensions are 4.25 x 6 inches.

You might be wondering why this size is important. It's because many businesses use I2 envelopes for everyday mail and correspondence.
If you need to order I2 envelopes online, you'll want to know the measurements in different units. In centimeters, I2 envelopes are 10.8 x 15.24, and in millimeters, they're 108 x 152.
Here's a quick reference guide to the standard I2 envelope dimensions:
Frequently Asked Questions
What size is a money envelope in inches?
Our money envelopes come in two sizes: small (2.5 x 4.2 inches) and large (3.5 x 8 inches). Choose the size that fits your needs for storing folded or unfolded bills and cheques.
Sources
- https://pe.usps.com/businessmail101
- https://blog.thepapermillstore.com/envelope-sizes-chart/
- https://www.printmagic.com/blog/what-are-the-standard-envelope-sizes-for-printing/
- https://smartpress.com/support/product-resources/understanding-envelope-sizes
- https://boxesgen.com/standard-envelope-dimensions-styles/
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