Guide to A3 Card Size

A3 Card Size

When it comes to the A-series in the ISO 216 paper size standards, the lower the number following the A, the larger the paper or card is. For instance, an A4 card is smaller than an A3 card but larger than A5. So, what are the measurements of an A3 card?

An A3 card measures 420 × 297 millimeters (16.54 × 11.69 inches). However, if you are going to print on A3 cards, then you might end up folding them into halves or quarters, giving it a final measurement of 210 × 297 millimeters (8.27 × 11.69 inches) or 210 × 148.5 millimeters (8.27 × 5.85 inches).

What Is an A3 Card?

What Is an A3 Card?

An A3 card is a sheet of cardstock that follows the ISO 216 sizing standards for paper. So, just as a sheet of A3 paper measures 420 × 297 millimeters (16.54 × 11.69 inches), so will an A3 card.

As you can see from its measurements, A3 cards are not the typical size one would use to print business cards, greetings cards, thank you notes, or to even make flashcards. However, due to their large size in comparison to something like an A6 card, you are more than welcome to fold or cut it down to size however you see fit.

As such, A3 cards can be quite versatile. Depending on how you use it, you can create sturdy brochures, tent cards, and flipbooks. It all starts with determining how small you want your cards to turn out from a single A3 card.

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For instance, you can cut an A3 card into the following sizes and quantities:

  • Poster—1 card at 420 × 297 millimeters
  • Flyer—folded to create 1 card with 210 × 297-millimeter pages
  • Flashcards—4 cards measuring between 210 × 148.5 millimeters
  • Index Cards—8 cards measuring 105 × 148.5 millimeters

While you can cut an A3 card into 16 pieces and more, it would probably be better to use A7, A8, or A10 cards instead since they are pre-cut to tinier dimensions.

Envelope Sizes for A3 Cards

Now, if you’d like to leave your A3 card or sheet intact and send it through the mail, then you will have to find an appropriately sized envelope. The good thing about ISO 216 standards is that finding the right envelope size for a specific paper or card size is a no-brainer.

To find the right envelope, just look for one that is sized A3. Its measurements will be slightly larger than 420 × 297 millimeters since it needs to hold onto the card without folding or wrinkling it.

In addition, you can look for C-series envelopes. The C-series follows the ISO 269 sizing standard, which is used exclusively for envelopes. For an A3 card or sheet of paper, you would need a C3 envelope.

That said, if you want to cut your A3 card down to a specific size, you might want to look for another envelope-sized A4 and smaller, depending on the final card size.


Baron Cooke has been writing and editing for 7 years. He grew up with an aptitude for geometry, statistics, and dimensions. He has a BA in construction management and also has studied civil infrastructure, engineering, and measurements. He is the head writer of

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