Postcard vs Self-Mailer vs Letter: Choosing a Direct Mail Format

Choose a postcard when the message fits on one side and the goal is a quick response, a folded self-mailer when you need room to explain without paying for an envelope, and a letter package when the mail is personal, confidential or carries a reply form. USPS size rules decide much of the cost: a postcard up to 4.25 x 6 in mails at the card price, and anything up to 6.125 x 11.5 in mails as a letter.

This guide covers addressed mail sent to a list. If you want every household on a carrier route without a list, start with our guide to Every Door Direct Mail, because EDDM pieces must be flat-size and follow their own rules.

How do postcards, self-mailers and letter packages compare?

All of these limits are in the USPS Domestic Mail Manual, section 201. Letter-size pieces must also have an aspect ratio, length divided by height, between 1.3 and 2.5. A square piece fails that test and pays a nonmachinable surcharge.

When is a postcard the right choice?

A postcard is right when one message and one action are enough, because there is nothing to open and the offer is read on the way from the mailbox to the recycling bin. It is also the cheapest format to print and, at 4 x 6 in, the cheapest to mail.

Going up to 6 x 9 or 6 x 11 in costs letter postage rather than card postage, and buys a much bigger billboard. On a 14pt card, which is 0.014 in thick, both sizes clear the 0.009 in minimum for letter-size cards. Spot UV postcards add a gloss coating over chosen areas of a matte card, so a logo or photograph shines and the reader can feel it.

When does a folded self-mailer make sense?

A folded self-mailer makes sense when one side of a card is not enough room but an envelope is more than the message needs. It carries a menu, a list of services or a campaign platform, mails at letter-size postage and costs less to produce than a letter package. USPS is strict about how it is built:

• Folded size between 3.5 x 5 in and 6 x 10.5 in, aspect ratio 1.3 to 2.5, up to 3 oz and 12 panels.
• The final fold runs along the bottom edge. On an oblong piece, it runs along the leading (right) edge.
• Up to 1 oz: at least 70 lb paper, sealed with two 1 in tabs, three glue spots or a continuous glue line.
• Over 1 oz: at least 80 lb paper, sealed with two 1.5 in tabs, four glue spots or a continuous glue line.
• Perforated or die-cut pieces need heavier paper, 100 lb up to 1 oz, and two 2 in tabs or three 1.5 in tabs.
• Tabs go on the top edge, one within 1 in of each side, or one on each side edge within 1 in of the top.

These rules are in DMM section 201.3.14. Common builds are an 8.5 x 11 in sheet folded in thirds to about 3.69 x 8.5 in, an 8.5 x 14 in sheet folded in thirds to about 4.69 x 8.5 in, and an 11 x 17 in sheet quarter-folded to 5.5 x 8.5 in. Panel widths for each fold are in our guide to brochure folds.

When is a letter package worth the extra cost?

A letter package is worth it when the mail has to look like correspondence, carry personal details, or hold a reply card and return envelope. It costs the most of the three formats to produce, because a letter, an envelope and any inserts all have to be printed, matched and inserted.

The standard carrier is a #10 envelope, 4.125 x 9.5 in. A window envelope lets the address printed on the letter show through, so the letter and the envelope can never be mismatched. Count the inserts: a machinable letter can weigh no more than 3.5 oz. Our guide to envelope sizes covers the other options.

Content rules matter here too. Bills, statements and personal correspondence must go First-Class Mail, under DMM section 133.3. USPS Marketing Mail can include personal information only when the piece contains explicit advertising or a request for a donation and the personal information relates directly to it, under DMM section 243.2.

When does variable data and personalization pay?

Personalization pays when the data changes what the reader should do, not when it only adds a first name. Variable data printing changes text, images or codes on every piece from a spreadsheet, at the same print speed, so the extra cost is mostly in preparing a clean list.

• Worth it: renewals and reminders that show the reader's own date or account details.
• Worth it: win-back mail that names the last purchase or the last visit.
• Worth it: donor mail that refers to the last gift and suggests the next one.
• Worth it: businesses with several locations, where each piece names the nearest one.
• Worth it: a unique code or QR code on every piece, so you can count exactly who responded.
• Not worth it: saturation mail such as EDDM, which has no names to merge, or a generic offer where the name is the only thing that changes.

Send the list as a CSV with clean column headers and we will map the fields. Printing, sorting and the postal drop can run as one job; see variable data and personalized mail for how that works.

Which format works for campaign mail?

Campaigns use all three: EDDM political mail for saturation coverage of chosen carrier routes, folded self-mailers for issue and GOTV pieces sent to a voter file, and personalized #10 letter packages for fundraising and endorsements. Campaign and union mail can also carry the Teamster Made union bug, which matters when a campaign is seeking labor endorsements; see our political campaign printing page. Mail timing for a field calendar is covered in our campaign printing guide.

Direct mail format questions

See postcards, self-mailers and letter packages on our direct mail printing page, or call with your list size and in-home date and we will tell you which format fits the budget.