Postcard design specs: bleed, DPI, and safe zones without the jargon

A win-back card fights for a lapsed customer’s attention with about two seconds of glance-time — and print quality decides whether those seconds read as “thoughtful note from a brand I liked” or “junk mail.” Print has exactly three physical rules. Learn them once and every card after prints right.

Resolution: 300 DPI or it prints soft

Screens forgive low-resolution art because they glow; card stock testifies against it. Print wants ~300 dots per inch — 1875×1275 pixels for a 4×6 card’s full artwork (which includes bleed, below). Around 180 DPI is the survival floor for photography; fine text and logos go visibly fuzzy well before that. Since the product photo is usually your card’s best argument — remember this? — its resolution is where quality checks matter most.

Bleed: the sacrificial eighth-inch

Cards are cut from big sheets and every cut drifts slightly. Artwork sized exactly to the 6×4 trim produces white hairlines wherever the blade wanders. The industry fix is bleed: extend backgrounds 0.125″ past the trim on all sides — hence the 6.25×4.25 design canvas. The outer ring exists to be cut off.

Safe zones: edges eat content too

The same drift claims anything close to the edge, so text and logos live at least 0.125″ inside the trim. The back carries the bigger reservation: USPS prints the recipient address, postage and barcode over roughly the right half, and ink there risks delay or rejection. The reliable division of labor: your creativity on the front, a functional back — one line, return address, the QR that carries the offer — with the address zone untouched.

Pre-send checklist for a win-back card

• Landscape, 1875×1275 px (or a print-exported PDF); backgrounds run to the canvas edge.
• Lead visual: something they’ll recognize or something new worth returning for — at honest resolution.
• Copy that greets rather than grovels; the offer visible, the QR doing the logistics.
• No static discount codes in print — advertise the gesture, mint the code at scan.
• Everything meaningful an eighth-inch inside the trim; address zone clear.
• Dark designs: one test card first.

Then let the system enforce it: a tool that measures artwork and refuses files below the floor is protecting your cost per won-back customer — a blurry card costs the same $1.50 as a sharp one and returns a fraction of the customers.