Direct Mail Postcard Sizes

What is the standard postcard size? The standard postcard size for mailing in the United States is 4.25" × 6" (or 4" × 6"), which may qualify for the First-Class postcard category when USPS conditions are met. However, postcard dimensions for direct mail campaigns range from the minimum 3.5" × 5" up to oversized flats at 12" × 15". This guide covers postcard size, dimension requirements, aspect ratio rules, and USPS classification considerations — so you can choose a format to review for your campaign goals and budget.

Quick Answer

A common direct-mail postcard size is the 6×9" postcard, which offers ample design space. USPS classification, postage, and preparation must be reviewed for the final piece. Standard postcards (4×6") may qualify for the First-Class postcard category when conditions are met. EDDM eligibility depends on USPS conditions including the final piece, carrier route, and preparation—not size alone. Postcard size is one factor in postage class and printing cost, so request a quote after specifications are reviewed.

Direct Mail Postcard Sizes at a Glance

Size Name	Dimensions	USPS Class	Approx. Postage	Best For
Standard Postcard	4" x 6" or 4.25" x 6"	First-Class postcard category when eligible	Quote after specifications	Budget campaigns, quick announcements
Large Postcard	5" x 7" or 5.5" x 8.5"	USPS classification reviewed per mailing	Quote after specifications	Promotions, coupons, event invitations
Jumbo Postcard	6" x 9"	USPS classification reviewed per mailing	Quote after specifications	High-impact format with more design space
Oversized Postcard	6" x 11" or 8.5" x 11"	USPS classification reviewed per mailing	Quote after specifications	Maximum visibility; real estate, home services
EDDM Candidate	6.5" x 9" or 6" x 11"	EDDM only if USPS conditions are met	Quote after specifications	Neighborhood saturation campaigns
EDDM Candidate	8.5" x 11" or 9" x 12"	EDDM only if USPS conditions are met	Quote after specifications	Restaurants, retailers

* USPS classification, postage, and eligibility depend on the final piece, quantity, preparation, entry plan, and current USPS conditions. Contact us for an itemized quote for your mailing.

The Most Popular Sizes — Explained

4" x 6" Standard Postcard

Standard size

Pros

May qualify for the First-Class postcard category when eligible
Compact format
Good for simple offers and announcements
Common direct-mail option

Cons

−Smallest canvas — limited design space
−Less visible in a full mailbox
−Lower response rates than larger sizes for most campaigns

Best for: Budget campaigns, quick announcements, appointment reminders, simple coupon offers

6" x 9" Jumbo Postcard

6" x 11" or 8.5" x 11" Oversized Postcard

Highest impact

Pros

Maximum visibility in the mailbox
Most design space for compelling imagery and copy
May be reviewed for EDDM when USPS conditions are met
High perceived value

Cons

−May require more production material than standard postcards
−Postage and EDDM eligibility are quoted and reviewed after specifications are provided

Best for: Real estate listings, home services, restaurant menus, high-value offers, EDDM campaigns

USPS Postcard Dimensions & Aspect Ratio Requirements

USPS has specific postcard dimension requirements that inform mail class, postage, and potential automation treatment; final eligibility is reviewed for each mailing. The postcard aspect ratio is one factor USPS reviews for applicable automation treatment. Here are key postcard size rules:

Minimum size

3.5" x 5" — pieces smaller than this are not mailable

Maximum postcard rate size

4.25" x 6" — pieces larger than this are classified as letters or flats

Minimum thickness

0.007" — pieces thinner than this may not process through automation equipment

Maximum thickness (letter)

0.25" — thicker pieces are classified as parcels

Aspect ratio

Length ÷ height is reviewed with the complete mailpiece for applicable USPS treatment. Example: a 6×9 postcard = 9÷6 = 1.5; request a review of a square or unusual format.

Address placement

Address must be in the lower right quadrant of the address side, with a clear zone for barcoding

Return address

Required for Marketing Mail to receive undeliverables; strongly recommended for all classes

Tabbing (self-mailers)

Folded self-mailers must be tabbed (wafer sealed) on the open edge — we handle this

We review all artwork against USPS specifications before printing and can identify issues for correction before production.

Frequently Asked Questions

Standard postcards up to 4.25" x 6" may qualify for the First-Class postcard category when USPS conditions are met. Marketing Mail does not have one generic postcard rate: USPS postage depends on the piece's mail category, weight, presort, entry point, and eligible adjustments. Larger postcards can offer more design space, but should be quoted using their specific USPS category and preparation.

The 6" x 9" postcard is a common direct-mail format because it offers more design space than a standard postcard. USPS classification, automation treatment, and postage depend on the final piece and preparation; it should be reviewed and quoted for the specific campaign. The 4.25" x 6" standard postcard is another common option.

USPS defines a postcard as a piece that is at least 3.5" x 5" and no larger than 4.25" x 6". Pieces larger than 4.25" x 6" are classified as letters or flats and should be reviewed for their applicable USPS classification and postage. A larger piece may be eligible for Marketing Mail when the final mailpiece and preparation meet USPS conditions; it does not qualify for the First-Class postcard category.

EDDM uses USPS-approved flat-size mail pieces, but eligibility and pricing depend on USPS conditions, not size alone. USPS reviews the final dimensions and weight, contents, carrier route, preparation, and current program requirements. Common formats such as 6.5" x 9", 8.5" x 11", and 6" x 11" should be reviewed before production; Mail Movers can confirm whether your specific piece and route qualify.

A return address is not required by USPS for postcards, but it's strongly recommended. Without a return address, you won't receive undeliverable pieces back, which means you can't clean your list. For Marketing Mail, pieces without a return address are discarded by USPS rather than returned.

The standard postcard size for mailing in the US is 4.25" x 6" (or 4" x 6"). This is the maximum size for the First-Class postcard category when USPS conditions are met. Anything larger is classified as a letter or flat and should be reviewed and quoted in its applicable category. The minimum mailable postcard size is 3.5" x 5".

USPS requires postcards to be between 3.5" x 5" (minimum) and 4.25" x 6" (maximum for postcard rate). The aspect ratio (length divided by height) must be between 1.3 and 2.5 to qualify for automation rates. Pieces outside this ratio incur a nonmachinable surcharge. Minimum thickness is 0.007" (7pt cardstock).

Standard postcards are 4" x 6" or 4.25" x 6" in inches. Large postcards are typically 5" x 7" or 5.5" x 8.5". Jumbo postcards are often 6" x 9". Oversized postcards range from 6" x 11" to 9" x 12". A format's dimensions alone do not establish EDDM eligibility; USPS reviews the final piece, route, preparation, and current conditions.

Ready to Print Your Postcards?

We print and mail postcards in all standard sizes. Get a free quote and we'll recommend the best size for your campaign goals and budget.

Postcard Sizes & Dimensions for Mailing: Complete USPS Guide