Postcard mailing format rules before you send artwork to print

A mailing card format has to pass two different checks. USPS decides whether the finished piece is mailable and which price category it earns. The printer decides how much bleed and trim tolerance the artwork needs. For a basic retail First-Class Mail postcard, the finished card must be rectangular, 5 to 6 inches long, 3.5 to 4.25 inches high, and 0.007 to 0.016 inch thick. Its address runs parallel to the long edge.

A 6 x 9 card needs a more careful answer. At the retail counter, it is too large for postcard pricing and pays the First-Class Mail letter price. In a qualifying commercial First-Class Mail mailing, however, 6 x 9 is the maximum postcard size and can earn card pricing. That difference gets missed often. Before design begins, tell the printer or mail house the finished size, mail class, retail or commercial entry method, address method, and barcode location.

Mailing card format limits that affect postage

USPS measures the finished piece after trimming, not the PDF canvas with bleed. It calls the dimension parallel to the delivery address the length. Turn the address 90 degrees and you may turn the same piece into a nonmachinable letter.

The current USPS physical standards for commercial cards and letters set these boundaries:

All three also need a machinable aspect ratio between 1.3 and 2.5. Divide length by height. A 6 x 9 card has a ratio of 1.5, so its proportions are fine. A square card has a ratio of 1 and is nonmachinable even when its two dimensions fit inside the letter limits.

As of October 8, 2026, the USPS price list puts a retail postcard at $0.65 and a stamped one-ounce letter at $0.82. Commercial First-Class Mail postcard prices run from $0.453 for 5-digit automation mail to $0.501 for machinable presorted mail before any applicable adjustments. These rates move. Recheck them when the job releases, not when the creative brief gets approved.

USPS Marketing Mail uses letter pricing for a letter-size card. There is no separate Marketing Mail postcard price. That can still be the sensible route for a larger prospecting run, but compare the service and preparation choices in the USPS Marketing Mail postage guide before treating the word "postcard" as a postal category.

Put the address where postal equipment expects it

The address and postage belong on the same side. For a letter-size card, USPS recommends keeping the delivery address inside its optical character reader area. That area starts 0.5 inch from each side, sits at least 0.625 inch above the bottom edge, and ends 2.75 inches above the bottom.

I would not hand a designer those four measurements and ask them to improvise a mailing panel. Use the mail house's template for the chosen size. Their indicia, address block, optional endorsement line, and Intelligent Mail barcode may be produced together, and the variable-data system needs room for the longest real company and street lines. Run the list through address verification before the mail merge as a separate production step.

The address establishes orientation and should read parallel to the long dimension. Keep promotional copy away from it. USPS calls for visible, legible addressing and generally specifies at least 8-point type. Use an obvious placeholder address on a nonproduction layer during design.

Reserve the barcode area before placing copy

If the Intelligent Mail barcode will print in the lower-right corner, reserve the barcode clear zone there. It spans 4.75 inches left from the right edge and 0.625 inch up from the bottom edge. For an automation mailing, the actual barcode must sit within tighter placement limits inside that zone.

The mailer can instead put the barcode in the address block. USPS then drops the lower-right clear-zone requirement, but no address line may run through the barcode. Its side clearance is at least 0.125 inch, and the block's bottom line remains 0.625 inch above the card's bottom edge.

That exception is useful, but it is not permission to fill every remaining millimeter. Ask one blunt production question: "Where will your system print the IMb?" Then lock that answer into the template. Keep a direct-mail QR code out of the postal barcode zone and leave enough quiet space for a phone camera to read it.

Bleed and safe area are printer instructions

USPS does not require a 0.125-inch bleed. Printers commonly do.

Bleed is artwork that extends beyond the finished trim so a small cutting shift does not leave a white sliver. If the printer asks for 0.125 inch on every edge, a 6 x 9 finished card needs a 6.25 x 9.25 artwork page. Background color and photos reach the bleed edge. They are meant to be cut.

The safe area works in the other direction. Printers commonly ask for important type and logos to stay 0.125 to 0.25 inch inside the trim. That margin is production advice, not a postal safe zone, and it does not replace the address or barcode clear areas. The printer's dieline wins because its press and cutter set the tolerance.

Name the bleed, trim, live area, and mail-panel layers. Hide template notes before export. Add crop marks only when the printer asks.

Choose stock by caliper before finish

Paper names are slippery. "Heavy cover" tells you less than the measured thickness of the finished, coated piece. USPS card-price limits use caliper: 0.007 to 0.016 inch, with a 0.009-inch minimum for commercial cards larger than 6 by 4.25 inches. Commercial postcards also have a paper-basis requirement, but basis-weight labels vary by sheet category and are easy to compare badly.

Ask the printer to confirm these facts in writing:

• Finished caliper after coating, not the stock's marketing name
• Whether the exact stock qualifies for the planned postal category
• Grain direction and stiffness if the format is unusual
• A physical sample for a large or expensive run

A common 14-point stock may land inside the card-price range, but its name is not proof. Coating, lamination, and manufacturing tolerances change the finished piece.

Coating is mostly a production choice. Gloss or UV can protect the image side. Matte cuts glare, while uncoated stock accepts handwriting well. The address side must take the mailer's inkjet or toner without smearing, so full UV on both sides is often the wrong order. Ask whether the finish has been tested on the variable-print equipment.

USPS cares that the address, postmark, markings, and barcode remain legible and that the barcode background has enough contrast. It does not tell a B2B marketer to choose "silk" over "matte." That language belongs to the printer.

Tabs apply to folded pieces, not a normal postcard

A single, unfolded sheet of postcard stock does not need tabs. A double postcard or folded self-mailer is a different construction with closure rules.

For a double postcard that is not sealed on every edge, USPS requires the fold at the top or bottom. The open edge parallel to the address needs one tab or another permitted closure at the middle of the length. Folded self-mailers have more detailed rules based on folds, panel layout, paper weight, finished weight, and closure method. Many common formats use two nonperforated tabs, but copying a tab count from another job is a bad shortcut.

Send the folded dummy to the mail house before artwork approval. If the design has a die cut, perforation, reply panel, unusual laminate, or attachment, get a USPS Mailpiece Design Analyst review. The PostalPro MDA service handles physical reviews and automation-compatibility questions.

Designer handoff checklist

Attach this to the creative ticket:

• State the finished trim size and orientation. Show which edge is the length.
• Name the mail class and whether entry is retail or commercial. "Postcard" is not enough.
• Include the printer's bleed and safe-area values on the template.
• Lock the postage or indicia area, delivery-address block, return-address position, and barcode location.
• Note the stock, finished caliper, coating on each side, and variable-print method.
• Supply a production PDF with fonts and images prepared to the printer's specification.
• Give the mail house a low-resolution proof with postal zones visible, plus the clean production file.
• Test the longest address, not the neat sample address.
• Get written approval from the printer and mail house. For an odd construction, add MDA review.

Keep the card's job simple after the format is safe. The B2B postcard examples page has creative layouts and copy approaches. There is no reason to squeeze those ideas into the postal specification sheet.

Frequently asked questions

What is the standard mailing card format for USPS?

For a retail First-Class Mail postcard, use a finished rectangle from 5 by 3.5 inches through 6 by 4.25 inches, with thickness from 0.007 to 0.016 inch. Keep the address parallel to the long edge. "Standard" gets fuzzy in commercial mail, where an eligible postcard may reach 9 by 6 inches.

Does a 6 x 9 postcard need letter postage?

It does when you mail it at the retail counter. The current retail postcard maximum is 6 by 4.25 inches, so a 6 x 9 piece falls to letter pricing if it meets the letter rules.

Commercial First-Class Mail is the exception people miss. A properly prepared 6 x 9 postcard can qualify for commercial card pricing. Do not buy stamps or approve an indicia until the entry method is settled.

How much blank space does USPS need on a postcard?

There is no single blank rectangle that answers every job. If the barcode prints in the lower right, preserve a 4.75-by-0.625-inch clear zone there. If it prints with the address, different clearances apply and the lower-right zone may not be required.

I use the mail house template. Guessing from a postcard received last week is how QR codes and legal copy end up under postal ink.

Do postcards need a bleed and safe area?

The printer usually needs both, but USPS does not set a universal bleed. A common request is 0.125 inch of bleed outside trim and 0.125 to 0.25 inch of safety inside it. Check the actual printer template. Postal clear zones remain separate, and they can consume much more room on the address side.