A5 Paper Size: When to Use It and When Not To

What A5 Paper Actually Is

A5 is 5.8 inches wide by 8.3 inches tall (148 × 210 mm). It is exactly half the size of A4 (which is 8.3" × 11.7"), created by folding an A4 sheet in half along the long edge. The ISO 216 paper standard defines it this way so that all A-series sizes maintain the same aspect ratio—fold any A-size in half and you get the next size down.

In the US, A5 is close to—but not identical to—half a letter-size sheet. Letter is 8.5" × 11", so half of that is 5.5" × 8.5". A5 is slightly wider and shorter. This matters when you are trying to fit US letter stock into an A5 layout, or when a printer's A5 tray is actually sized for US half-letter.

When A5 Makes Sense

Postcards and promotional mailers. A5 is the standard size for a postcard in many markets. It fits postal regulations, feels substantial enough to not be dismissed as junk, and costs less to mail than a larger format. If you are sending a batch of promotional pieces or event announcements, A5 is efficient.

Greeting cards. A5 folded in half creates a card that is 2.9" × 5.8" when closed—a standard greeting card size. Many card templates are built around this dimension because it is easy to handle, fits in a standard envelope, and looks intentional rather than makeshift.

Pocket notebooks and pads. A5 is the size of a small notebook that fits in a jacket pocket or bag without bulk. If you are printing branded notepads or small journals, A5 is the right choice. It feels like a finished product, not a scrap.

Half-page flyers and handouts. If you need to print something on a budget and can fold a standard sheet in half, A5 is practical. Two A5 pieces fit on one A4 sheet, so you halve the paper cost. This works for event flyers, class handouts, or internal memos where the format itself does not carry a message about quality.

When A5 Does Not Work

Business correspondence. Never use A5 for a letter, invoice, or formal document. It signals either that you ran out of proper paper or that the content is not important enough for full-size treatment. A prospect or client will notice.

Anything that needs to look premium. A5 feels small and informal. If the piece is meant to convey authority, professionalism, or value, use A4 or letter-size. The extra space gives you room to breathe and signals that you took the job seriously.

Documents that need to be filed or archived. A5 does not fit standard filing systems. If the recipient needs to keep the piece in a folder or binder, A5 creates a logistics problem. Stick with A4 or letter.

Anything with dense text. A5 is cramped. If you have more than a few paragraphs, the type becomes small and hard to read, or you have to reduce margins to the point of looking unprofessional. Use the larger format.

The Practical Reality

A5 is a tool for specific jobs, not a general-purpose size. It works because it is cheap to produce and mail, and because it is small enough to feel like a keepsake rather than a flyer. But that same smallness is a liability if the content needs to feel important or if the reader needs to do anything with it besides glance and discard.

If you are choosing between A5 and A4, ask yourself: does the small size serve the message, or does it undermine it? If you are unsure, go larger. You can always trim down later. You cannot add space back.

Paper Stock for A5

A5 is typically printed on the same weights as A4: 80 GSM for everyday use, 100 GSM or higher for something that needs to feel substantial. Postcards are often 250–300 GSM (roughly 110–130 lb cover stock) so they do not bend in the mail. Folded greeting cards work best on 200–250 GSM so the fold does not crack. Check your printer's specifications—not all machines handle heavier stock well, and some have size restrictions that affect A5 capability.