Postcard Paper: Weights, Coatings, and the USPS Limits That Decide Your Postage

What postcard paper should you use?

Most mailed postcards run on 14pt coated cardstock, which measures 0.014 inches thick and sits comfortably inside the USPS card standard. That standard allows a card between 3.5 by 5 and 4.25 by 6 inches and between 0.007 and 0.016 inches thick, so 16pt is the heaviest postcard stock that still mails at card rates and 18pt is not a card at all. Choose coated for photographic color, uncoated when anyone has to write on the piece, and confirm the caliper before you confirm the postage class.

Sending a postcard mailing? Get an itemized quote, or run your artwork through the free file check first.

What postcard paper measurements actually mean

Three different units get used for postcard paper, and they measure different things. Mixing them up is the most common reason a stock that looked right on a spec sheet arrives feeling wrong.

Points measure thickness, not weight

A point is one thousandth of an inch of caliper. A 14pt stock is 0.014 inches thick, 16pt is 0.016 inches, and 18pt is 0.018 inches. Points describe the physical thickness of the sheet, which is what USPS measures and what a recipient feels between their fingers.

Pounds and gsm measure weight

Basis weight in pounds and grams per square meter both describe how much a given area of the sheet weighs. Neither converts cleanly to caliper, because two sheets of identical weight can differ in thickness depending on how the fibers are bulked and how much coating sits on the surface. A 100 lb cover stock typically lands somewhere near 0.010 to 0.011 inches, noticeably thinner than 14pt, which is why a 100 lb card can feel flimsy in a mailbox even though the number sounds heavy.

Here is the practical rule. When a printer quotes points, they are telling you about thickness. When a supplier quotes pounds or gsm, ask what caliper that translates to on the specific sheet being run, because that is the number USPS will measure.

Common postcard stocks side by side

The weight column is deliberately approximate, and the two basis-weight rows vary in caliper by mill. Caliper is the number that governs postage eligibility, so caliper is the number to put in your specification. Stepping from 14pt to 16pt adds to the print line and nothing at all to the postage, because both stocks sit inside the same card standard. How much it adds moves with quantity, which is why it belongs in a quote rather than a published figure.

The USPS limits that decide what you pay

The stock you pick can move the piece into a different mail class, and that cost repeats on every piece in the run rather than landing once as a setup charge. Two thousandths of an inch is the whole margin between a card and a letter.

The card standard has a thickness ceiling

USPS defines a postcard in DMM 101.1.2 as a rectangular piece between 3.5 by 5 and 4.25 by 6 inches, and between 0.007 and 0.016 inches thick. Both ends of that thickness range matter. Text-weight paper under 0.007 inches fails the standard because it cannot survive automated handling, and anything over 0.016 inches is no longer a card.

Why 18pt reprices a 4 by 6 postcard

An 18pt sheet is 0.018 inches thick, which puts it 0.002 inches over the card maximum. A 4 by 6 piece printed on 18pt postcard stock does not qualify for card pricing and gets rated as a letter instead. At current rates that is the difference between the First-Class Mail postcard presort Mixed rate of $0.495 per piece and the First-Class Mail letter presort Mixed rate of $0.707 per piece, per USPS Notice 123 (Price List) effective July 12, 2026. On a 10,000-piece drop that single stock decision adds more than $2,000 in postage for a difference nobody holding the card can detect.

If the piece is a rack card, a counter handout, or a leave-behind, 18pt is a good choice and the thickness is the point. If it goes in the mail at card size, 16pt is the ceiling.

Past 4.25 by 6 inches, size takes over

Once a piece exceeds 4.25 by 6 inches it is no longer a card regardless of stock, so the thickness ceiling stops being the binding constraint. The letter maximums take over at 6.125 inches high, 11.5 inches long, and 0.25 inches thick, and a piece that exceeds any one of those three becomes a flat. This is why the popular 6 by 9 and 6 by 11 formats price as letters, and why the standard sizes in our EDDM mailing services of 6.25 by 9 and 6.25 by 11 inches sit in flat territory by design.

The useful consequence is that on oversized postcards you can specify 16pt or heavier for the feel you want without changing the postage tier, because the trim size already set it. The stock question gets easier the larger the piece gets.

How format and stock map to postage

The First-Class Mail and Marketing Mail letter and card rates above are the Mixed presort tier, the highest presort price and the one most lists actually qualify for, per USPS Notice 123 effective July 12, 2026. EDDM Retail is a saturation rate with no presort tier, and Marketing Mail flats are quoted per job. Marketing Mail postcards are quoted at the Marketing Mail letter rate. A deeper presort earns a lower price than the Mixed figures shown, and a tighter sort typically saves several cents per piece against Mixed, which is the single largest postage lever available once the format is fixed. Current figures for every class live on our USPS postage rates guide.

Stock, machinability, and the presort discount

Automation discounts assume the piece can run through USPS equipment without jamming. Very thin stock flexes and double-feeds, and a card that is stiff but warped can fail the same way. Both outcomes cost the automation rate the format was chosen for, which is usually a larger loss than the stock choice ever saved.

Pieces rated as letters carry an extra exposure that cards do not. A First-Class Mail letter that fails the DMM 101 physical standards for machinability, whether from rigidity, an out-of-range length-to-height ratio, or an uneven thickness, carries a $0.49 nonmachinable surcharge under USPS Notice 123. Presorted mail that fails machinability is priced through separate nonautomation categories instead, so check machinability rather than assume a flat add-on. That is why an oversized card on heavy stock deserves a machinability check before the run rather than after.

Two habits prevent most of this. Keep mailed cards at 12pt or heavier so they hold their own shape, and keep the address block and the barcode clear zone free of artwork, heavy varnish, and dark flood coverage so the address reads on the first pass.

Not sure which size and stock combination fits your budget? See what postcards cost, or request a quote with your quantity and trim size.

Coated, uncoated, and what each finish costs you

Coating changes how ink sits on the sheet, how the piece survives handling, and whether anyone can write on it. Pick the finish from the job rather than from the sample that looked best on a desk.

Coated stocks

Coated two sides, usually written C2S, carries a mineral coating on both faces that holds ink on the surface instead of letting it soak in. Colors stay saturated, photographs hold their detail, and fine reverse type stays crisp. The tradeoff is that ballpoint and most pens will not take, and the surface can show fingerprints under heavy dark coverage.

Gloss coating reflects the most light and gives the punchiest color, which suits photography and bold price-led offers. Matte and dull coatings scatter light instead, so long copy reads more easily and there is no glare under a kitchen light.

Uncoated stocks

Uncoated sheets absorb ink, which softens color slightly and spreads fine detail a little. In exchange you get a surface anyone can write on with any pen, which matters for appointment reminders, response cards, and anything a recipient is meant to fill in and return. Uncoated also reads as less promotional, which is frequently the point on a notice or a personal-feeling mailing.

Recycled and kraft stocks are worth a note here. Recycled uncoated is available at postcard calibers and mails exactly like any other uncoated sheet of the same thickness. Kraft carries a natural brown base, so every ink on it shifts warmer and white has to be printed rather than assumed, which makes it a color decision more than a paper decision.

Protective and specialty coatings

Aqueous coating is a water-based flood applied inline that adds scuff resistance at low cost, and it is the sensible default on any card with heavy dark ink coverage that has to cross the postal stream. UV coating cures to a harder, glossier film for a more dramatic finish. Soft-touch laminate produces a velvet feel that performs well on high-ticket offers, and spot gloss over a matte base draws the eye to one element.

One production note is worth knowing before you specify a laminate. Film laminate adds caliper on every face it covers, and a typical 1.2 mil film adds about 0.0012 inches per side. A 14pt card laminated on both sides lands near 0.0164 inches, which exceeds the 0.016 inch card maximum and reprices the piece as a letter. If a mailed card has to carry film on both sides, drop to 12pt; 14pt works only with film on one side.

Finish selection at a glance

Choosing postcard paper by job

The right stock changes with what the piece has to survive and what the recipient has to do with it. Four common jobs, and what each one argues for:

Saturation and EDDM drops

Saturation mail rewards cost discipline, because the postage is already the cheapest commercial rate available and the print side is what moves your cost per piece. EDDM Retail postage runs $0.260 per piece and EDDM entered at the Business Mail Entry Unit runs $0.259 per piece, per USPS Notice 123 effective July 12, 2026. Since our EDDM sizes are flats rather than cards, 14pt with an aqueous coat gives a substantial piece that survives bundling and route handling without paying for a premium stock the recipient will not consciously notice.

Targeted First-Class mailings

When the piece carries a time-sensitive offer and goes to a purchased or house list, First-Class buys speed and forwarding. Here the card format is usually worth protecting, so hold the postcard cardstock at 16pt or below and apply the laminate caveat above before finalizing. A tighter presort is the lever that moves this postage, not the paper.

Pieces that get written on or scanned

Appointment reminders, response cards, and anything with a signature line need an uncoated face or an uncoated panel, or the pen simply will not take. QR codes are a separate problem: they scan fine on gloss in even light but can wash out under direct light, so matte or uncoated is the safer surface for a code you actually want used. Keep the quiet zone clear and print the code in solid black rather than a screened tint.

Variable data is a third case. Inkjet addressing and personalization lay down more reliably on uncoated and matte surfaces than on high gloss, which is why a gloss front with a matte or uncoated back is a common specification on personalized cards. It buys the color on the side that sells and the print reliability on the side that carries the address.

When double-thick stock is worth it

Duplexed stock, two sheets bonded to produce a single thick card, shows up on invitations and premium announcements where the edge itself is part of the impression. It reliably exceeds the card thickness maximum, so treat any duplexed piece as a letter or a flat from the start and price the postage accordingly. On a mailed promotional postcard the extra cost rarely earns its keep, and the same budget spent on list quality usually returns more.

What we run, and why the stock question comes up early

We print and mail from a single Lakeland, Florida production facility, and the stock decision gets made in the same conversation as size and quantity because the three are connected. Color work runs on two Xerox Iridesse presses and on Xerox Versant equipment, and black and white work runs on Xerox Nuvera equipment. 14pt coated two sides is the house default for mailed postcards, because it clears the card standard with margin, takes inkjet addressing on the reverse, and holds up through presort and carrier handling. The full range of sizes and stocks sits on our postcard printing page.

In 35 years of production work the pattern that repeats is not a preference for premium stock. It is that a stock chosen without checking the postage class costs more than the stock itself ever saved. That check takes one measurement, and it is among the first things our team asks about on a new postcard job.

Getting the file and the stock right before you order

Specify caliper, not just a marketing name. Words like premium and ultra describe nothing a press operator can set. Write the specification as points, coating, and sides, for example 14pt C2S with aqueous coating on the front and an uncoated back.

State the postage class in the same sentence as the trim size. If the piece has to mail at card rates, the trim must be 4.25 by 6 inches or smaller and the finished caliper including any coating or laminate must be 0.016 inches or less.

Send a print-ready PDF with bleed and a clear safe zone. Keep the address block and barcode clear zone free of artwork, since a card that fails automation loses the presort discount that justified the format in the first place. You can start from a free template on the design templates hub and check the file yourself with the free file check before it reaches production.

Ask for a stock sample on a first run. Caliper is measurable but feel is not, and a physical sample settles the 14pt versus 16pt question faster than any written description.

Ready to price it? Send your quantity, trim size, and stock preference and our team will come back with an itemized quote covering printing, data, mail services, and postage. Call 863-687-6945 or request a quote.

Frequently asked questions

What is the best paper for postcards?

For mailed postcards, 14pt coated two sides is the most common choice, because it measures 0.014 inches and clears the USPS card thickness range of 0.007 to 0.016 inches with room to spare. Choose 16pt when a heavier feel is worth the added cost, and choose uncoated when the recipient has to write on the card.

Is 14pt or 16pt better for postcards?

Both mail at card rates, so the decision is feel against cost. 16pt is noticeably stiffer in the hand and suits high-ticket offers, while 14pt is the practical default for volume mailings and leaves headroom under the 0.016 inch card maximum for a one-side laminate.

Can you mail an 18pt postcard?

You can mail it, but not at card rates. At 0.018 inches an 18pt sheet exceeds the 0.016 inch maximum in the USPS card standard, so a card-size piece on 18pt is rated as a letter instead. That moves a presorted piece from the First-Class Mail postcard presort Mixed rate of $0.495 to the First-Class Mail letter presort Mixed rate of $0.707 per piece, per USPS Notice 123 effective July 12, 2026.

Is 65 lb cardstock thick enough for postcards?

It qualifies, but only just. 65 lb cover runs roughly 0.008 to 0.009 inches, which sits near the bottom of the USPS card thickness range and flexes enough that it can double-feed in automated handling. For anything that has to survive the mail stream, start at 12pt and prefer 14pt.

How many grams per square meter is a 14pt postcard?

A 14pt coated sheet generally falls in the 320 to 350 gsm range, but treat that as an approximation rather than a conversion. Points measure caliper and gsm measures weight, and the relationship shifts with the bulk and coating of the specific sheet, so specify the caliper whenever postage eligibility depends on it.

Should postcards be glossy or matte?

Gloss delivers the strongest photographic color and the most visual punch, while matte reads more easily on longer copy and avoids glare. Matte or uncoated is also the safer surface for QR codes and for any panel a recipient writes on. Many mailed cards use gloss on the front and a matte or uncoated back for exactly that reason.

Does heavier postcard paper improve response rates?

Stock affects how the piece feels and how long it survives on a kitchen counter, but the list and the offer move response far more. Spend on address quality and targeting first and on postcard paper stock second, since a premium card delivered to a stale address returns nothing.

Does MPA help with getting the file ready?

Yes, on request. Most customers send a print-ready PDF, or start from a free template on the design templates hub and run it through the free file check. If you need help getting the file ready, mention it when you request a quote and we will scope it with the job.