TLDR: Choose the mailing method before choosing the card. A 4-by-6-inch card is a practical choice for a short offer and can fall within the USPS dimensional range for single-piece First-Class Mail postcard pricing. Larger cards provide more room, but they do not receive that price merely because a printer calls them postcards. EDDM has a different set of requirements, and a thin 5-by-7-inch or 6-by-9-inch card may not be large enough to qualify as an EDDM flat.
The best direct mail postcard sizes depend on what recipients need to understand, how the cards will be distributed, and which postal classification applies. Start with the campaign objective: promote one offer, announce an event, explain several services, distribute a neighborhood menu, or provide a coupon worth keeping. Then select a format that fits the message without creating an avoidable postage or mailability problem.
Quick guide to common direct mail postcard sizes
| Finished size | Useful campaign role | Postal planning note |
|---|---|---|
| 4 × 6 inches | Simple offer, reminder, announcement, appointment recall or short event invitation | Within the USPS postcard-price dimensional range when all other First-Class Mail requirements are met. |
| 4.25 × 6 inches | A compact card needing slightly more layout room | At the maximum length and height allowed for the USPS single-piece postcard-price category; thickness and construction still matter. |
| 5 × 7 inches | Photo-led promotion, coupon, invitation or offer needing more explanation | Too large for the USPS postcard-price category. A thin 5 × 7 card also does not meet the EDDM flat-size trigger from dimensions alone. |
| 6 × 9 inches | Multiple services, map, larger photo, schedule or two-part offer | Too large for postcard pricing. A thin 6 × 9 card does not exceed the stated EDDM length or height trigger. |
| 6.5 × 9 inches | Neighborhood promotion needing substantial visual and copy space | Its height exceeds the EDDM flat trigger, but every other eligibility and preparation requirement must still be checked. |
| 6 × 11 inches | Menu-style promotion, service overview, large coupon or route-saturation campaign | Its length exceeds the EDDM flat trigger, subject to all other applicable requirements. |
Commercial printers commonly offer formats such as 4 by 6, 4.25 by 6, 5 by 7, 6 by 9, and 6 by 11 inches. That availability describes print products, not one universal postal category. Confirm the finished dimensions—not merely the product name—before approving artwork or estimating postage.
A printed postcard is not always a USPS postcard-price mailpiece
In ordinary conversation, almost any unfolded promotional card can be called a postcard. USPS uses more specific dimensional and construction rules when determining whether a card qualifies for the single-piece First-Class Mail postcard price.
According to the official USPS postcard-size guidance, a rectangular card in that category must be at least 3.5 by 5 inches and no more than 4.25 by 6 inches. Its thickness must be between 0.007 and 0.016 inches. A card can be printable and mailable while still being too large, too thick, too thin, or otherwise ineligible for that particular price.
USPS Marketing Mail does not have a separate postcard price category. A promotional card sent using Marketing Mail is priced according to its applicable classification, such as a letter or flat, rather than receiving a special rate simply because it looks like a postcard. This is why a mailing-method-first decision prevents unpleasant budget surprises.
When a 4-by-6-inch postcard makes sense
Choose 4 by 6 when the campaign can communicate one idea quickly. Good candidates include a service reminder, grand-opening announcement, limited offer, event date, appointment recall or simple invitation. The format is compact enough to discourage copy bloat and sits within the USPS dimensional window for postcard pricing, provided the piece satisfies every other requirement.
A practical message hierarchy is straightforward: lead with the offer or reason for mailing, add one supporting detail, and finish with one primary action. A QR code can be useful, but attach it to a reason to scan: “View available dates,” “Claim the neighborhood offer,” or “See the full menu.” Include a readable short URL as a fallback.
Do not force a complex service explanation onto a small card merely to pursue a particular postage category. If the recipient needs a map, qualifications, several service options and a coupon, the design will usually benefit from a larger format or a simpler message.
Choosing a larger addressed postcard
Formats such as 5 by 7 and 6 by 9 inches give photos, maps, schedules and offer details more breathing room. They can be sensible for home-service campaigns, real-estate announcements, nonprofit appeals, restaurant promotions and events. They are not eligible for the USPS single-piece postcard price because they exceed its maximum dimensions.
Treat the larger size as a strategic purchase, not permission to fill every corner. The additional space should improve comprehension from the mailbox: a stronger headline, clearer image, larger coupon, useful map or more legible service comparison. Printing every possible detail is not the same as communicating clearly.
Before committing, ask the mailing provider how the piece will be classified and prepared. A larger card may qualify as a letter when it meets the relevant standards, while a genuinely flat-size piece follows different rules. Classification depends on more than the two face dimensions, so get the answer against the final stock, thickness, orientation and construction.
How EDDM postcard sizes work
Every Door Direct Mail is a route-based option for reaching addresses in selected local postal routes. USPS describes it as suitable for materials such as postcards, menus and flyers. Its online tool supports route selection and demographic filtering based on U.S. Census data. Review the current USPS EDDM tool and requirements before building the campaign.
EDDM Retail pieces must satisfy flat-size criteria. USPS lists a minimum of 5 inches long, 3.5 inches high and 0.007 inch thick, but the piece must also exceed at least one of these dimensions: 10.5 inches long, 6.125 inches high or 0.25 inch thick. The listed maximum is 15 by 12 by 0.75 inches, with a maximum weight of 3.3 ounces.
That “must exceed” condition is the easy part to miss. A thin 5-by-7-inch card does not cross any of those flat triggers. Neither does a thin 6-by-9-inch card: its 9-inch length is below 10.5 inches, and its 6-inch height is below 6.125 inches. By comparison, a 6.5-by-9-inch piece crosses the height trigger, while a 6-by-11-inch piece crosses the length trigger.
Dimensions alone do not establish final eligibility. Weight, thickness, shape, flexibility, construction, addressing, required markings and mail preparation can also matter. Check the final physical specification rather than resizing artwork based on a single measurement.
Match the size to the campaign job
- One offer and one action: Start with 4 by 6 or 4.25 by 6. These sizes encourage a disciplined message and may fit the postcard-price dimensional range.
- Event invitation or photo-led announcement: Consider 5 by 7 when visual impact and readable details matter more than postcard-price eligibility.
- Several services or a useful map: A 6-by-9-inch card provides room for a short service list, coverage area, map and response prompt without turning the type microscopic.
- Neighborhood saturation: Evaluate an EDDM-compatible format such as 6.5 by 9 or 6 by 11, then verify the full specification before design approval.
- Coupon intended to be retained: Give the coupon a clear boundary and expiration date. Keep essential business and redemption information on the portion recipients are likely to save.
- Menu or detailed schedule: Use the larger canvas only when the information genuinely helps someone decide. If details change frequently, direct readers to a maintained landing page rather than printing fragile information in bulk.
Measurement should influence the layout too. Use a unique URL, QR destination, coupon code, dedicated phone extension or lead-source field. These devices do not guarantee better performance, but they make it possible to compare the mailing with other campaign activity.
Build the mailing panel before the promotional design
Reserve the address and postage area at the beginning, not after the front has been polished. For First-Class Mail postcards using postcard pricing, USPS requires the delivery address to run parallel to the longer dimension. An address running parallel to the short dimension can make the piece nonmailable.
Ask the mailing provider for the correct template and lock its mailing areas before creative work begins. Do not assume that a template from another printer, an older campaign or a different mailing program has the same clear zones.
- Confirm the finished trim size, stock, thickness and orientation.
- Identify the mailing service and expected postal classification.
- Reserve room for the delivery address, return address, postage or indicia, and any required markings.
- Use the selected printer’s current bleed, safe-area, color, resolution and file-format instructions.
- Keep headlines, QR codes, coupon terms and contact details away from trim and mailing clear zones.
- Order or review a proof with the mailing panel visible, not merely the promotional side.
- Request a final mailability review when using rounded corners, unusual shapes, laminates, magnets, die cuts, attachments or other nonstandard treatments.
For general artwork preparation, review this guide to preparing print-ready files. If you still need a production partner, use a structured process for choosing a local print shop and ask specifically about postal review, list handling, proofs and mailing support. For deeper background on unusual processes and materials, specialty print and production topics can help you frame questions for the provider.
Common questions about postcard sizing
What is the standard size for a direct-mail postcard?
There is no single size for every campaign. A 4-by-6-inch card is a common compact format, but printers also sell larger direct-mail cards. The correct size depends on the message and postal method.
Does a 5-by-7-inch card receive postcard pricing?
No. It exceeds the 4.25-by-6-inch maximum for the USPS single-piece First-Class Mail postcard-price category. It may still be mailable under another classification, which should be confirmed before postage is budgeted.
Can a 6-by-9-inch card be used for EDDM?
A thin 6-by-9-inch card does not exceed the EDDM flat length or height trigger from dimensions alone. Do not assume EDDM eligibility merely because 6 by 9 is sold as a direct-mail postcard.
Can finishes or attachments change eligibility?
They can affect thickness, flexibility, shape, weight or machinability. Obtain postal and production review before using magnets, attachments, heavy laminates, die cuts or other unusual constructions.
Finalize the mailing method before ordering
Prepare a short campaign brief containing the objective, audience, quantity, mailing method, delivery area, deadline, offer, response mechanism and artwork status. Bring it to the printer or mail-service provider before choosing stock or approving the final size.
The central rule is simple: choose direct mail postcard sizes by the job they must do and the postal category they must satisfy. A compact card is efficient when the message is simple. A larger card earns its cost when the extra space improves understanding. An EDDM piece must meet EDDM requirements—not merely look large in a design mockup. Confirm the finished physical piece and mailing plan together before production begins.