Postcard Sizes Explained From 3x5 to 6x9
From a 3x5 reminder to a 6x9 attention-grabber, postcard size changes cost, impact, and postage. This guide maps every size to its best use and the USPS rules that decide your mailing rate.
The standard postcard sizes are 3x5, 4x6, 5x7, and 6x9 inches, and the right one depends on your message and your postage. USPS treats 3x5 to 4.25x6 as postcard rate; larger sizes mail at letter or flat rates. Pick 4x6 for value, 6x9 for standout mailers. 4OVER4 prints every size with mailing services.
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Postcard sizes in one paragraph
The four standard postcard sizes, 3x5, 4x6, 5x7, and 6x9 inches, trade off cost, impact, and postage. USPS charges the cheap postcard rate only up to 4.25x6 inches; larger cards mail at letter or flat rates. 4x6 is the value default, 6x9 the standout mailer. Whichever you pick, design to the exact size with proper bleed and safe margins. 4OVER4 prints every size and can mail them for you.
The standard postcard sizes at a glance
Four sizes cover the vast majority of postcard jobs. The 3x5 is compact and cheap, good for reminders and simple notices. The 4x6 is the workhorse, big enough for a real message, small enough to mail at the lowest rate. The 5x7 gives more room for design and photos. The 6x9 is the standout, a large card that dominates the mailbox.
Each size is a balance of three things: how much you can say, how much it costs to print, and how much it costs to mail. The rest of this guide walks each size and, crucially, the USPS rules that tie size to postage. To order any of them, start at our postcards category or the standard postcards product.
USPS rules: how size sets your postage
This is the part that decides your campaign budget. USPS charges its lowest First-Class rate, the postcard rate, only for cards between 3.5x5 and 4.25x6 inches. A 4x6 postcard fits comfortably inside that window. The moment a card exceeds 4.25x6, it is billed as a letter, and once it passes 6.125 inches tall or 11.5 inches long, it becomes a flat, at a higher rate again.
So a 5x7 or 6x9 postcard is often mailed at letter or flat pricing, not the cheap postcard rate, which changes the math on a large mailing. If postage is the priority, stay within the postcard-rate window; if impact matters more, pay the higher rate deliberately. 4OVER4 offers direct-mail postcards with mailing services so the postage is handled for you.
What is the largest postcard USPS allows?
The largest postcard that still earns the USPS postcard rate is 4.25x6 inches. Everything from 3.5x5 up to that ceiling is billed at the postcard rate, which is exactly why 4x6 is the size most mailers land on: at 101.6 x 152.4 mm it uses almost all the space the cheap rate allows, and it leaves a sensible margin against the 4.25x6 line.
Go past 4.25x6 and the piece is priced as a First-Class letter instead, and the letter ceiling is 6.125 inches tall by 11.5 inches long. A 5x7 at 127 x 177.8 mm and a 6x9 at 152.4 x 228.6 mm both sit inside that letter band, so they mail normally, just at the higher rate. Cross 6.125 x 11.5 and the card becomes a flat, at higher postage again, which is the band a mini poster or an oversized promo piece falls into.
So there are two honest answers, and the one you want depends on the budget: 4.25x6 is the largest postcard at postcard rate, 6.125 x 11.5 is the largest card that still mails as a letter. Decide the ceiling before the design starts, because trimming a 6x9 layout down to 4.25x6 later means rebuilding it, not scaling it. Custom die-cut shapes are measured at their widest and tallest points, so confirm the final dimensions before the run. Direct-mail postcards with mailing services handle the postage side for you.
3x5 and 4x6: the value sizes
The 3x5 postcard is the smallest common size, inexpensive to print and mail, and best for short, single-message pieces: appointment reminders, save-the-dates, quick notices. It qualifies for postcard postage and ganks up efficiently in bulk, so it is cheap at volume. Build it at 900 x 1500 px, and keep it to one headline plus one line of detail, because 76.2 x 127 mm punishes long copy.
The 4x6 is the default for a reason. It clears the USPS postcard-rate window, holds a headline, an offer, and a call to action comfortably, and prints economically in large runs. At 1200 x 1800 px it is also the file most designers already have a template for. For most marketing mailers, 4x6 is the size to beat. Both are covered in our bulk printing guide for the pricing side.
5x7 and 6x9: the impact sizes
When getting noticed matters more than the cheapest postage, size up. The 5x7 gives designers room for larger photos and more copy, a common choice for invitations, announcements, and premium offers. At 1500 x 2100 px there is room for a full-bleed photo and a readable block of text on the same face. It usually mails at letter rate rather than postcard rate, so factor that in.
The 6x9 is the attention play. In a stack of standard envelopes, a large postcard sits on top and gets read first, which is why it is popular for real estate, retail promotions, and any offer that needs to break through. At 1800 x 2700 px it also holds a map, a property grid, or a coupon block without crowding. It costs more to mail, but the higher response can justify it. Pair it with custom shaped postcards when you want to stand out even further.
Setting up your file for any postcard size
Whatever size you choose, the file setup follows the same rules at different dimensions. Build the document at the exact trim size, add 0.125 inch of bleed on every edge so background art runs past the cut, and keep text and logos inside a 0.125 inch safe margin so nothing important is trimmed. Set color to CMYK and images to 300 DPI at final size.
Remember a postcard has two sides: a front for the message and a back that often carries the address block and postage area, so keep that zone clear on mailers. Our bleed and trim guide shows exactly how to set these lines, and the online Designer starts you at the right size automatically.
How to choose the right postcard size
Work from two questions: what do you need to say, and what will you spend on postage. If the message is short and the budget is tight, 3x5 or 4x6 keeps both printing and mailing cheap. If you need room for photos or a premium feel, 5x7 fits. If standing out in the mailbox is the whole point, 6x9 earns its higher postage.
For a mailing, run the numbers on postage at each size before you decide, because at scale the rate difference dwarfs the printing difference. Use the size chart below and the live pricing panel to compare, then order the size that fits your message and your math.
Order your postcards, printed and mailed
Once you have picked a size, ordering is simple: set the size, stock, quantity, and finish, upload your two-sided artwork, and choose whether to add mailing. A 4x6 in bulk for a value campaign, a 6x9 for a standout push, both come off the same press.
Configure your postcards below to see live specs and pricing at each size, or add direct-mail service so 4OVER4 handles the postage and delivery. For the wider category, visit postcards printing.
Wally sizes a postcard the smart way
Message first, postage second, then the size
Wally picks a postcard size by balancing two things: how much he needs to say and what USPS will charge. Short message and tight budget, he takes 4x6 to stay in the cheap postcard-rate window. Needs to stand out in the mailbox, he pays a bit more for a 6x9. Then he builds the file to the exact size with bleed. 4OVER4 prints every size and can mail them too.
Order your postcards →Quick reference
Postcard sizes, use cases, and postage
Every standard postcard size in inches, millimeters and pixels at 300 DPI, matched to its best use and how USPS is likely to bill it. Start the file at the pixel figure in the table, keep type inside the safe margin, and run the background past the trim so nothing important is cut. Rates depend on current USPS rules.
| Size | Millimeters | Pixels at 300 DPI | Best for | Postage note |
|---|---|---|---|---|
| 3x5 in | 76.2 x 127 mm | 900 x 1500 px | Reminders, notices, save-the-dates | Qualifies for the low postcard rate; cheapest to mail. |
| 4x6 in | 101.6 x 152.4 mm | 1200 x 1800 px | Marketing mailers, offers, the default | Fits the postcard-rate window; best value for volume mail. |
| 5x7 in | 127 x 177.8 mm | 1500 x 2100 px | Invitations, announcements, premium offers | Usually mails at letter rate, not postcard rate. |
| 6x9 in | 152.4 x 228.6 mm | 1800 x 2700 px | Standout promotions, real estate, retail | Mails at letter or flat rate; costs more but grabs attention. |
| Custom shapes | Set by your die line | Die line width x height at 300 DPI | Standout branding pieces | Rate depends on final dimensions; confirm before mailing. |
Step by step
Pick and order a postcard size in 6 steps
- Define your message length Decide how much you need to say. A short reminder suits 3x5 or 4x6; photos and more copy point to 5x7 or 6x9. One offer and one call to action fit a 4x6 face without crowding.
- Check the postage impact Confirm whether your size fits the USPS postcard-rate window (up to 4.25x6) or mails at letter or flat rate, since that drives cost at scale. Anything larger than 6.125 x 11.5 inches leaves the letter band entirely and is billed as a flat.
- Choose the size that balances both Weigh message and postage together. For most mailers 4x6 wins; for standout, 6x9 earns its higher rate. If the two are close, price the same quantity at both sizes before you commit, because postage repeats on every card while the print cost does not.
- Set up the file to the exact size Build at the trim size with 0.125 inch bleed and safe margin, CMYK color, and a clear address area on the back.
- Configure stock, quantity, and finish Set the options in the configurator and watch the live price, ordering enough to clear a bulk price break.
- Add mailing if you want it handled Choose direct-mail service so 4OVER4 prints, addresses, and mails the postcards for you.
Specs and pricing
Postcard specs and live pricing
Once the size is set, the rest is stock, quantity, and finish. Here are the live specs and per-unit pricing for custom postcards at 4OVER4, straight from the configurator.
| Quantity | Price Per Unit | Total |
|---|---|---|
| 50 | 33.0¢ | $16.48 |
| 100 | 24.2¢ | $24.16 |
| 200 | 15.9¢ | $31.86 |
| 300 | 12.8¢ | $38.45 |
| 400 | 11.3¢ | $45.04 |
| 500 | 10.3¢ | $51.62 |
| 600 | 9.89¢ | $59.31 |
| 700 | 9.57¢ | $67.00 |
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Common Questions
Common questions about postcard sizes
What are the standard postcard sizes?
The four standard postcard sizes are 3x5, 4x6, 5x7, and 6x9 inches. The 3x5 is compact and cheap for short notices; the 4x6 is the workhorse that fits the USPS postcard-rate window and holds a full message; the 5x7 gives room for photos and premium designs; the 6x9 is a large card built to stand out in the mailbox. 4OVER4 prints all four sizes plus custom shapes.
How do I choose the right postcard size?
Balance two things: how much you need to say and what postage will cost. For a short message and the lowest mailing cost, 4x6 stays inside the USPS postcard rate and prints cheaply in bulk. For more design room, 5x7 works. To dominate the mailbox, 6x9 earns its higher postage. At scale, the postage difference usually matters more than the printing difference.
What does postcard printing cost and how are prices set?
Cost depends on size, paper stock, finish, and quantity, with quantity the biggest lever, since the per-unit price drops in bulk. Larger sizes like 6x9 cost more to print and to mail than a 4x6. The 4OVER4 configurator shows the live per-unit price as you set the size and options, so you can compare sizes and quantities before ordering.
What sizes, stocks, and finishes are available for postcards?
4OVER4 offers the standard 3x5, 4x6, 5x7, and 6x9 sizes plus custom shapes, on a range of stocks from standard card weights to premium and specialty papers, with finishes like matte, gloss, and UV coating. Each option is shown in the postcard configurator, so you can match the size, stock, and finish to your campaign and budget.
Which postcard size is cheapest to mail?
Sizes within the USPS postcard-rate window, roughly 3.5x5 up to 4.25x6 inches, mail at the lowest First-Class rate, which makes 4x6 the value default. Once a card exceeds 4.25x6 it is billed as a letter, and larger still it becomes a flat, both at higher rates. If postage is your priority, stay inside the postcard-rate window. Rates follow current USPS rules.
How long do postcards take to print and ship?
Standard postcards print quickly and staple sizes often support fast lanes. If you add direct-mail service, allow time for addressing and mail induction on top of production. Read the production time and delivery separately, and for a dated campaign build in a buffer. The 4OVER4 configurator shows timing for your size and quantity before you order.
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Configure your postcards at 4OVER4, compare sizes and quantities with live pricing, and add mailing to have them printed and sent for you.
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