What Is The Standard Mailbox Size?

If you know the standard mailbox size, you can keep your letters and packages secure when you are away from home. The United States Postal Service has very strict mailbox regulations. It is important to know what size is a standard mailbox if you want to run a small business or for residential use. In today’s post, I will reveal what is the size of a standard mailbox.

What Is The Standard Mailbox Size?

The standard mailbox size is approximately 19 inches long x 6 ½ inches wide x 8 ½ inches high. A mailbox dimension and design should always be approved by the Postmaster General. You can also go for a mailbox with a lock to keep your letters and packages safe and secure. The standard mailbox size with a lock is around 22.8 inches long x 11 inches wide x 15 inches high.

A letterbox is a horizontal or vertical mail slot and has a cut through the middle or lower half of a front door. The standard letterbox size is about 30 cm by 5 cm (12 inches x 2 inches).

Different Types Of Mailboxes

I hope you now know the standard mailbox size for packages and orders. Generally, there are four different mailbox sizes available in the market. You can consider the following dimensions to find the perfect mailbox for your house.

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  1. Small Mailbox

A small mailbox is perfect for residential use. Most people don’t receive a lot of mail or just receive letters from time to time. This type of mailbox measures anywhere from 12 inches tall to 5-19 inches wide and 4-14 inches deep. It can easily hold about 10 to 15 letters and two rolled magazines/newspapers.

  1. Medium Mailbox

A medium-sized mailbox is perfect for standard residential properties. It is about 6-20 inches tall, 6-20 inches wide, and 10-20 inches deep. This type of mailbox can easily hold everything a small mailbox can hold including small boxes and packages. If you love shopping online or receive lots of subscription magazines, this mailbox can fulfill your needs!

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  1. Large Mailbox

Large mailboxes are super beneficial for businesses. It can also be used for residential properties to collect large packages. It is about 12-20 inches tall, 10-20 inches wide, and 6-20 inches deep. Large mailboxes can easily hold small/medium-sized boxes, letters, catalogs, magazines, and newspapers.

  1. Extra-Large Mailbox

Extra-large mailboxes are great for collecting large packages. It can be installed at the end of your driveway on a post or on the side of your porch. An extra-large mailbox is 20-40 inches tall, 15-40 inches wide, and 10-17 inches deep.

Mailbox Rules

You should remember the following mailbox regulations before installing one.

  • They should be 41 to 45 inches in height from the street up to the bottom of the mailbox.
  • The mailbox door should be 6 to 8 inches from the curb when is closed.
  • Your mailbox should always face outward.
  • It must be placed on the right-hand side of the road.

However, the front door delivery option is also available for elderly or disabled people from the USPS. Make sure you regularly check your mailbox as mailboxes experience a lot of wear and tear

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What Size Mailbox Should I Get?

If you generally receive an average volume of mail, a small to medium-sized mailbox may be perfect for you. However, if you frequently receive high volumes of mail or larger parcels, you may want to consider upgrading to a larger mailbox with greater storage capacity.

What Is Considered A Large Mailbox?

If you receive a large amount of mail a large rural or package mailbox, also called a T3 mailbox, is a good choice. The maximum T3 mailbox size is 13.63” x 7.75” tall on the sides, 12” tall in the center and 16.5” deep.

What Is The Correct Height For A Rural Mailbox?

Height: Mailboxes are typically installed with the bottom of the mailbox located 41 to 45 inches above the roadway surface.

Can I Just Put Up A Mailbox?

Important: Before installing, moving or replacing your mailbox or mailbox support, you will need to contact your Postmaster or mailperson from your local Post Office™. All mailboxes must be approved by the Postal Service™. Custom made mailboxes will be approved by the Postmaster if they meet established standards.

What Are The Dimensions Of A Standard Metal Mailbox?

Standard sized steel mailbox made of galvanized steel. 18 3/4″ long, 8 3/4″ high, 6 1/4″ wide.

How Big Is Too Big For A Mailbox?

Dimensions for an approved package mailbox are no larger than 22 1/2 inches long, 8 inches wide and 11 1/2 inches high.

What Is The Average Size Of An Apartment Mailbox?

Mailboxes may be in a variety of sizes and shapes but the smallest dimensions for a standard tenant mailbox must not be smaller than 3 inches high by 12 inches wide by 15 inches deep. Anything larger than that is acceptable for the USPS regulations.


In the above post, I’ve discussed what is the standard size of a mailbox in detail. A mailbox of size 19 inches long x 6 ½ inches wide x 8 ½ inches high can hold mail and small packages/ orders. You can now easily shop for the right mailbox for yourself after knowing the standard mailbox size.

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