Print Your Own Postcards: JPG Specs for Moo, Postable, and Local Print

You designed a 4x6 postcard in Canva, downloaded the JPG, uploaded it to Moo, and the proof preview shows your headline cut in half because you ignored the bleed area. Postcard printing — through Moo, Postable, Vistaprint, or the local print shop — has surprisingly strict rules that designers learn the expensive way. This is the spec sheet that catches print rejections before they cost you the order.

Postcards are a deceptively complex format. Small canvas, two sides, postal regulations on the back, bleed and trim issues on both, color profile expectations that vary by printer. The good news: once you understand the three zones, the rest of the rules cascade naturally. The bad news: until you understand them, every print run is a roll of the dice. By the end of this guide you will know exactly what to send the printer and exactly what to expect back.

Background: the printing reality behind a 4x6 card

The press does not actually print a 4x6 sheet. It prints a much larger sheet (often 19x25 or 13x19) with many postcards arranged on it, then a cutting blade trims down to the final size. The blade is not perfect — typical tolerance is plus or minus 1/16 inch on a digital press, sometimes worse on offset. That tolerance is exactly why bleed exists. If the printer's design extends right to the trim line and the blade cuts 1/16 inch inside, you get a white sliver on one edge.

The three zones every postcard has

Every print-ready postcard layout has three zones, and they exist whether you draw them or not:

• Trim line: The final cut edge of the card. A 4x6 card trims to exactly 4 x 6 inches.
• Bleed area: A 0.125-inch (3 mm) margin past the trim where background extends but no critical content lives. The press cuts somewhere in this zone, so your background needs to extend through it but text cannot.
• Safe area: A 0.125-inch (3 mm) margin inside the trim where critical text and logos must stay. Anything closer to the edge risks getting trimmed.

So a 4x6 postcard with bleed exports at 4.25 x 6.25 inches total, and the safe area for your text is 3.75 x 5.75 inches centered.

Step-by-step postcard prep

1. Pick the trim size. 4x6, 5x7, or A6 are the common formats.
2. Add bleed. Extend canvas to trim + 0.125 inch each side.
3. Place safe-area guides. 0.125 inch inside trim on every side.
4. Design both sides. Front: visual hero; back: address area, message, return address.
5. Export front and back as separate JPGs. 300 DPI, sRGB, quality 95.
6. Verify dimensions and DPI. Use the DPI converter and the image info tool.
7. Bundle if printer accepts multi-page PDF. Use the JPG to PDF converter with front and back as pages 1 and 2.
8. Compress if file size exceeds printer cap. Run through the JPG compressor at quality 90.
9. Upload and proof. Always order a single proof card before the full run.

Printer-by-printer specs

Different printers handle bleed differently:

• Moo: Wants a PDF or JPG at 4.13 x 6.13 inches for a 4x6 card (1.5 mm bleed each side). Accepts JPG at 300 DPI.
• Vistaprint: Standard 0.125-inch bleed. 4.25 x 6.25 inches for 4x6. JPG or PDF at 300 DPI.
• Postable: Bleed handled automatically if you start from their template. Custom uploads at 4.25 x 6.25 inches.
• Local print shop: Ask. Most independent print shops use either 0.125-inch or 0.25-inch bleed depending on their cutter tolerance.

Common mistakes and fixes

• Mistake: designing at trim size with no bleed. Fix: extend the background 0.125 inch past trim on every side.
• Mistake: text within 0.125 inch of trim. Fix: pull text into the safe area.
• Mistake: exporting at 150 DPI. Fix: 300 DPI minimum at print size; verify with the DPI converter.
• Mistake: white background with no bleed. Fix: technically OK because trimming into white still produces white, but verify with the printer.
• Mistake: address-side text in the postage area. Fix: leave the upper-right 1.5 x 1.5 inches clear for the stamp.
• Mistake: skipping the proof. Fix: always pay for one proof card before printing 200.

Real-world postcard examples

A wedding couple in Brooklyn sent 240 save-the-date postcards through Moo. They built the design in Canva, exported at 4.25 x 6.25 inches with 3 mm bleed, ran the JPG through the JPG compressor to land under Moo's 25 MB upload cap, and ordered one proof before committing to the full run. Total cost: about $170 plus stamps.

A hostel chain in Lisbon prints custom postcards for each property — 200 cards per location across 7 locations. They standardize on Vistaprint specs (4.25 x 6.25 inches, JPG quality 95, sRGB), maintain one master InDesign template with swappable photos, and run quarterly batch orders.

A small art studio in Portland sells boxed sets of 12 art postcards through their Etsy shop. They print through a local offset shop using 4x6 cards with 0.25-inch bleed and CMYK PDFs. The local shop's quality on saturated colors beats online digital print noticeably.

DPI: the silent rejection

Postcards print at 300 DPI minimum. A 4x6 card at 300 DPI is 1,200 x 1,800 pixels minimum; with bleed at 0.125 inch each side, the file is 1,275 x 1,875 pixels. A Canva download at the default size sometimes comes out at 150 DPI, which prints as visibly blurry. Use the DPI converter to check the embedded DPI on the JPG before uploading.

For 5x7 postcards (the larger US standard, increasingly popular for save-the-dates and announcements), the print-ready size with bleed is 5.25 x 7.25 inches, which at 300 DPI is 1,575 x 2,175 pixels.

Color profile: CMYK or sRGB?

Most online postcard printers ask for sRGB JPGs and convert to CMYK on their side. Moo specifically takes sRGB. Vistaprint takes either but recommends sRGB. Local print shops with offset presses sometimes ask for CMYK PDFs. The rule of thumb: read the printer's spec sheet. When in doubt, send sRGB at 300 DPI.

Verify color profile and resolution on a sample card with the image info tool before uploading the batch. Catching a profile mismatch on the first card saves having to re-upload 80 wedding save-the-dates.

Postcard format comparison

Format	Trim size	With bleed	Pixel target @ 300 DPI	USPS rate
Standard postcard	4 x 6 in	4.25 x 6.25 in	1275 x 1875	Postcard rate
Large postcard	5 x 7 in	5.25 x 7.25 in	1575 x 2175	First-class
Square postcard	5 x 5 in	5.25 x 5.25 in	1575 x 1575	First-class
A6	105 x 148 mm	111 x 154 mm	1311 x 1819	International
Mini (Moo MiniCard)	2.75 x 1.1 in	2.875 x 1.225 in	862 x 367	N/A (not mailable)

Two-sided design considerations

Postcards have a front and a back. The back is where the printer puts the address and stamp area on stamped postcards, or where you put a personal message on greeting-style cards. Most printers ask for two separate JPGs, one per side. Some accept a single PDF with both sides. The back side has the same bleed and safe area rules as the front — leave at least 3/8 inch (10 mm) on the right side of the back for the address window if the postcard goes through USPS unfolded.

The bundle PDF workflow

For multi-design postcard sets — a series of holiday cards with different illustrations, or a hostel chain with one card per city — bundle the front-and-back JPGs into a single multi-page PDF using the JPG to PDF converter. Most printers accept the bundle and run it through their imposition software directly. This is cleaner than uploading 18 separate JPGs for nine designs.

File size and compression

A 4x6 postcard JPG at 300 DPI and quality 95 is around 4 to 6 MB depending on detail. That is usually fine for upload, but printers with size caps (Moo limits at 25 MB per file) will reject anything heavier. Run the file through the JPG compressor at quality 90 to drop it to 1.5 to 2.5 MB without visible loss at the print scale. Save the uncompressed version for archive.

Advanced tips for serious postcard runs

• Use the color palette tool to extract a cohesive palette from your hero photo and apply to the back-side typography.
• Photograph the proof card under daylight. Indoor LED light shifts the proof; the printed batch should match daylight viewing.
• Print 10 percent extra. Always order 10 percent over your needed count. Postcards get bent, lost, or returned.
• Test a glossy vs matte sample. Most printers offer both; glossy pops photos, matte handles handwriting better.
• Use the aspect ratio calculator for non-standard sizes. Square 5x5 cards need explicit aspect math.
• Convert legacy designs from PSD or AI. The PNG to JPG converter handles flat PNG exports; the EPS to JPG converter handles vector legacy.
• Build a master template. One InDesign file per trim size, swap content, export. Cuts per-postcard prep from 2 hours to 20 minutes.

The pre-flight checklist

1. Final file size matches printer-required dimensions including bleed
2. Background extends to the bleed edge (no white margin around the design)
3. All text inside the safe area (3 mm in from trim)
4. 300 DPI minimum at print size
5. sRGB color profile (or CMYK if printer specifically asks)
6. Front and back files uploaded separately, named clearly
7. Address-side leaves 10 mm clear on the right for USPS

Common rejections and how to fix them

1. Low DPI. Re-export at correct resolution or reduce the planned print size.
2. No bleed. Extend background to full file dimensions; do not leave white margin.
3. Text in bleed area. Pull text into the safe zone.
4. Wrong dimensions. Re-export at the printer's exact spec, not the trim size.
5. Transparent background. Flatten on solid color before export.

FAQ

Can I use a phone photo as the postcard front?

Yes, if it is high enough resolution. A 12 MP phone photo (4,032 x 3,024) prints clean at 4x6 with bleed. Convert HEIC via the HEIC to JPG converter first.

What about die-cut or unusual shapes?

Most online printers don't offer die-cut postcards. Local print shops do but add a setup fee. Stick with rectangular for online orders.

How long do postcards take to ship?

Moo: 5-7 business days. Vistaprint: 3-5 business days standard. Local: same-day to 48 hours.

Can postcards have foil or embossing?

Moo offers foil; Vistaprint does for some product lines; local offset shops handle embossing. Each adds significant cost and lead time.

Do USPS regulations affect my design?

Yes for mailed cards. Leave the address area clear, postage area clear (upper-right), and use minimum 4x6 size for the postcard rate. Anything larger ships first-class letter rate.

What if I want to print just one or two postcards?

Moo's minimum is around 25 cards; Vistaprint goes lower. For one-offs, print at home on photo paper.

Can I include a QR code on the back?

Yes. Generate the QR code at 300 DPI and place it in the message area, not the address area. Test scanning from a printed proof before the full run.

Choosing the print method

For runs of 1-50 cards, digital print through Moo or Postable is the right choice — no setup fee, per-card cost in the 80-cent to 1.50-dollar range. For runs over 200, offset print at a local shop typically beats online digital on both price and quality. For runs over 1,000, definitely offset.

Paper stock, finish, and how they affect your design

Postcard paper stock matters more than designers expect. Moo's standard cardstock (350 gsm) feels premium and accepts saturated color well. Vistaprint's standard stock (300 gsm) is thinner and slightly less saturated. Both offer premium options (450+ gsm pearl or textured stocks) for higher-end runs.

The finish — gloss, matte, or satin — interacts with the design. Glossy finish pops photographic detail and looks polished but shows fingerprints. Matte feels sophisticated and reads well for typography-heavy designs but mutes saturated colors by 10-15 percent. Satin splits the difference and is the safest default.

If the postcard back will be handwritten (wedding save-the-dates, personal messages), specify matte or uncoated. Glossy finishes do not accept pen ink reliably.

Edge cases: oversized postcards, panoramic formats, and unusual shapes

Standard postcards are 4x6 or 5x7, but USPS allows postcards up to 4.25 x 6 inches for the postcard rate and considers anything larger a first-class letter. The 6x9 jumbo postcard format ships at first-class rate but commands more attention in a mailbox — useful for real estate or restaurant marketing where standing out matters more than postage cost.

Panoramic postcards (4x9 inches) are a niche format used for landscape photography and architectural projects. Most online printers do not stock the format; specialty printers like Catprint and Smartpress handle it. The pipeline is identical: 300 DPI, sRGB, JPG quality 95, bleed at 0.125 inch each side.

Die-cut shapes (rounded corners, custom outlines) require a separate die file from the printer — usually a vector path defining the cut. Online printers offer pre-set shape options; custom die cuts are local-print-shop territory and add setup fees.

Going deeper: variable-data printing for personalized cards

Wedding save-the-dates, business holiday cards, and event invitations often need per-recipient personalization — guest name on the front, custom message on the back. Online printers (Moo, Vistaprint, Postable) support variable-data printing through CSV upload: you provide a base JPG and a CSV with personalized fields, and the printer composites the variable text onto each card.

The base JPG must leave space for the variable text. Plan the layout with a placeholder text block, export the base, and confirm the CSV columns match the printer's expected schema. Moo's variable-data feature handles up to 5,000 unique cards per order; Vistaprint handles smaller runs but accepts more complex layouts.

Direct-mail postcard marketing

Small businesses use postcards for direct-mail marketing campaigns: real estate agent farming, restaurant grand openings, dentist appointment reminders. The pipeline adds two layers beyond the basic postcard: mailing-list management (typically a CSV from a service like USPS EDDM, Vericast, or a local mailing house) and USPS Indicia placement (a printed permit mark instead of a stamp).

Most online printers handle EDDM (Every Door Direct Mail) as a single-flow product: upload the postcard JPG at 4.25 x 9.25 inches (the EDDM size), select the carrier routes, and the printer plus USPS handle the mailing. The address side leaves the lower-right clear for USPS markings and the Indicia.

Postcards as art prints

A growing micro-trend: postcards sold as boxed art print sets. Artists print 12 to 24 different designs as a numbered, signed set sold through Etsy or direct-to-consumer. The pipeline is identical to standard postcards but with attention to color fidelity — art print buyers notice color shifts more than greeting card recipients do. Soft-proof in Photoshop or Affinity Photo against the printer's ICC profile before committing to the print run.

Start with your existing design. Check the dimensions with the aspect ratio calculator, verify DPI with the DPI converter, and run the JPG through the JPG compressor for the final upload. The image info tool verifies the embedded color profile, the photo editor handles last-minute color tweaks, and the tool index covers the envelope, label, and address-list exports that complete the mailing.