ID Card Sizes and Thickness: CR-80, 30 Mil, Explained

Almost every ID card, membership card, hotel key and access badge in the world is the same size, and that size has a name: CR-80. The thickness is quoted separately, in thousandths of an inch called mils, and 30 mil is the standard. This page covers what those numbers mean, when you would want something different, and which combinations actually fit the printers and badge holders you already own. If you are working through a printer purchase, our guide to choosing an ID card printer is the pillar this sits under.

CR-80, and the dimensions that matter

A CR-80 card measures 3.375 by 2.125 inches, or 85.6 by 54 millimeters. It is the same footprint as a credit card, which is not a coincidence: the size comes from the same banking card standard, and that is why an ID badge slips into a wallet slot.

The practical consequence of CR-80 being near universal is that everything downstream assumes it. Badge holders, lanyard clips, retractable reels, slot punches, laminating pouches, wallet inserts and card printers are all built around those dimensions. Stray from CR-80 and you are sourcing every accessory separately.

You will occasionally see CR-79 mentioned. It is very slightly smaller, about 3.303 by 2.051 inches, and its normal job is to be an adhesive-backed card that sticks onto a CR-80 card. It is a workaround for reprinting the visual design of a badge without replacing the credential underneath, not a size to build a program around.

Larger formats exist for event and visitor badges, but once you leave CR-80 you also leave the card printer world and end up on a label printer or a sheet-fed press, which is usually a different purchase entirely.

Thickness, and what a mil is

Card thickness is quoted in mils. One mil is one thousandth of an inch. It is not a millimeter, and mixing the two up is the single most common confusion here.

The standard is 30 mil, which is 0.76 millimeters. That is credit card thickness, and unless you have a specific reason to do otherwise, it is what you want.

The reason 30 mil dominates is mechanical. Card printers pick cards from a hopper one at a time using a roller and a gate set to a specific gap. Feed thin cards through a hopper expecting 30 mil and you get double feeds, where two cards go through together and one comes out blank. Most printers have an adjustable card thickness lever precisely because this is a known failure mode, but the adjustment has limits.

Badge accessories assume 30 mil as well. A slot punch, a rigid holder and a badge clip are all sized for it.

Thinner and thicker cards, and when they show up

Thin cards do exist, commonly around 10 mil, and they are usually there because someone wanted a cheap card for a short-lived purpose: a one-day event badge, a promotional card, a mailer insert. They are noticeably flimsy, they do not survive a wallet, and many card printers will not feed them reliably. If you are printing thin stock, check the printer's specification before you buy a case of it.

Thicker cards, above 30 mil, generally appear for one of two reasons. Some programs laminate a 30 mil card, which adds thickness on top of a standard card rather than starting thicker. And some legacy proximity credentials use a clamshell body at roughly twice standard thickness.

Clamshell is worth a word, because it is the one thickness that actively costs you something. It is too thick for a card printer to print on, so a program running clamshell issues two things: the clamshell for the door and a separate printed badge for the photo. It also does not fit a standard slot punch, a wallet, or most badge holders. We do not stock clamshell for that reason. The credential inside one is ordinary 125 kHz HID Prox, so a standard 30 mil ISO prox card encoded with the same facility code and card number works on the same readers and carries the photo as well. Our prox card guide covers what that swap involves.

If you are running technology cards from an existing system, the thickness is decided for you by whatever your readers expect. Check before you order.

PVC, composite, and what the difference buys you

Standard blank cards are PVC. It prints well, it is inexpensive, and for a badge that lives in an office it lasts for years.

Composite cards blend PVC with polyester, usually quoted as a percentage split. The polyester makes the card stiffer, more resistant to snapping, and considerably more tolerant of heat. That heat tolerance is the reason composite matters for retransfer printing: retransfer bonds a film to the card under heat and pressure, and a plain PVC card can warp under it. If you are running a retransfer machine, ask whether your stock is rated for it.

The other case for composite is abrasion. A badge that spends its life being pulled out of a reel, tapped against a reader and wiped down with cleaning products will look tired sooner than an office badge. Composite plus a protective overlay buys real time there. Our healthcare and manufacturing pages go into what that looks like in practice.

Every card we sell is CR-80 PVC at 30 mil, and any magnetic stripe on it is high coercivity, three track.

Card surface and print quality grades

Blank cards are not all the same, and the difference is the surface rather than the plastic underneath.

A graphic quality card has a surface prepared specifically to accept dye sublimation printing evenly. A cheaper card can have a slightly inconsistent surface, and what you see on the finished badge is banding, blotchy areas in solid color fills, or photos that look washed out in one corner.

This is worth knowing because the temptation with card stock is to buy on price per card, and the difference between a good card and a poor one is small in cents and obvious on the badge. It is also expensive in a less visible way: a poor surface leaves more residue on the printhead, which means more cleaning cycles and a shorter head life.

If your cards look inconsistent and you have already changed the ribbon, the stock is a reasonable next suspect. Our troubleshooting guide covers how to tell the difference between a stock problem, a ribbon problem and a printhead problem.

Magnetic stripes, punches, and orientation

Cards can be ordered with features already built in, and it saves trouble to decide before you buy rather than after.

A magnetic stripe is applied to the back of the card during manufacture, so it is not something you add later. High coercivity, usually written HiCo, resists accidental erasure far better than low coercivity and is what nearly every access, time-and-attendance and hotel application uses. The setting on your encoder and the stock you buy need to agree either way.

A slot punch is the hole for a clip or a lanyard, and it goes in after printing, never before. Most card printers will not feed and print a card that already has a hole in it, so pre-punched stock and in-house printing do not mix. Settle portrait or landscape early all the same, because the artwork has to leave the slot area clear, and a hole punched through a photo is the usual sign that the design and the punch were decided separately. If you have ended up with pre-punched cards anyway, the workaround is to print onto adhesive-backed mylar and apply it to the punched card. Which holders, reels and clips follow from that choice is covered on our badge accessories page.

Orientation is worth a moment of thought. Portrait badges read better when worn on a lanyard, which is why so many organizations use them, while landscape suits a wallet card. The card is the same either way; the design and the punch position are what change.

What we stock, and what to order

For the overwhelming majority of programs the right answer is graphic-quality CR-80 PVC at 30 mil, and that is our standard blank card. It fits every printer we sell, every badge holder on the market, and every accessory you already own.

Order technology cards, prox, smart or magnetic stripe, only where the card has a job beyond identification, and match them to your existing system rather than to a spec sheet. Our prox card guide covers what has to match.

You can see thickness, size, material and pack size on every card page in Cards and Credentials, and the plain stock sits on our blank ID cards page. If you are unsure whether a card will feed in the printer you have, tell us the model and we will confirm it before you order a case.