Print & Paper Size Reference

Every paper size in millimetres and inches — A and B series, US Letter and Legal, envelopes and photo prints — with the geometry behind the A series.

A series (ISO)

Size	Millimeters	Inches
A0	841 × 1189 mm	33.11 × 46.81 in	One square meter of paper — the series’ anchor
A1	594 × 841 mm	23.39 × 33.11 in
A2	420 × 594 mm	16.54 × 23.39 in
A3	297 × 420 mm	11.69 × 16.54 in
A4	210 × 297 mm	8.27 × 11.69 in	The world-standard letter paper outside North America
A5	148 × 210 mm	5.83 × 8.27 in
A6	105 × 148 mm	4.13 × 5.83 in	Standard postcard
A7	74 × 105 mm	2.91 × 4.13 in
A8	52 × 74 mm	2.05 × 2.91 in

B series (ISO)

Size	Millimeters	Inches
B0	1000 × 1414 mm	39.37 × 55.67 in
B1	707 × 1000 mm	27.83 × 39.37 in
B2	500 × 707 mm	19.69 × 27.83 in
B3	353 × 500 mm	13.9 × 19.69 in
B4	250 × 353 mm	9.84 × 13.9 in
B5	176 × 250 mm	6.93 × 9.84 in	Common for books and workbooks

US sizes

Size	Millimeters	Inches
Letter	215.9 × 279.4 mm	8.5 × 11 in	8.5 × 11 in — the North American A4
Legal	215.9 × 355.6 mm	8.5 × 14 in	8.5 × 14 in
Tabloid / Ledger	279.4 × 431.8 mm	11 × 17 in	11 × 17 in
Half Letter	139.7 × 215.9 mm	5.5 × 8.5 in	5.5 × 8.5 in — planners and invoices
Executive	184.2 × 266.7 mm	7.25 × 10.5 in	7.25 × 10.5 in

Envelopes

Size	Millimeters	Inches
#10 (US business)	104.8 × 241.3 mm	4.13 × 9.5 in	Fits Letter folded in thirds
DL (ISO business)	110 × 220 mm	4.33 × 8.66 in	Fits A4 folded in thirds
C5	162 × 229 mm	6.38 × 9.02 in	Fits A4 folded in half, or A5 flat
C4	229 × 324 mm	9.02 × 12.76 in	Fits A4 unfolded
A7 announcement	133.4 × 184.2 mm	5.25 × 7.25 in	5.25 × 7.25 in — fits 5×7 cards

Photos & cards

Size	Millimeters	Inches
Photo 4×6	101.6 × 152.4 mm	4 × 6 in
Photo 5×7	127 × 177.8 mm	5 × 7 in
Photo 8×10	203.2 × 254 mm	8 × 10 in
Photo 11×14	279.4 × 355.6 mm	11 × 14 in
Photo 16×20	406.4 × 508 mm	16 × 20 in
Business card (US)	88.9 × 50.8 mm	3.5 × 2 in	3.5 × 2 in
Business card (EU)	85 × 55 mm	3.35 × 2.17 in
Postcard (US min)	127 × 88.9 mm	5 × 3.5 in	5 × 3.5 in minimum for USPS

Scaling one size onto another

Whether the shapes match decides whether anything is wasted.

From

onto

—

√2 is the only shape that survives being halved

Cut a sheet in half across its long side and the halves have the reciprocal shape: a sheet of ratio r becomes two of ratio 2 ÷ r. For the shape to be unchanged you need r = 2 ÷ r, so r² = 2 and r = √2. No other number works — that one equation is the whole of ISO 216.

Starting ratio	After halving
1.2500	1.6000	a different shape
1.3000	1.5385	a different shape
1.3330	1.5004	a different shape
1.4142 (√2)	1.4142	unchanged
1.5000	1.3333	a different shape
1.6000	1.2500	a different shape
1.2941 (US Letter)	1.5455	a different shape

Which is why A4 onto A3 is a clean 141.4% enlargement with nothing cropped and no margin left over, while A4 onto US Letter fits at only 93.9%. US Letter is 1.2941; halve it and you get 1.5455, a different sheet again. And Legal is not Letter enlarged — it is Letter with extra length, ratio 1.6481, which is why a Letter layout never fills it tidily.

Bleed, trim & safe margins

For anything professionally printed: extend background artwork 3 mm (0.125 in) past the trim edge on every side (the bleed), and keep text and logos at least 3–6 mm (0.125–0.25 in) inside the trim (the safe margin). Cutting machines wander about a millimeter; bleed hides it, the safe margin protects your words. The A-series magic: every size is the previous one folded in half, all sharing the same √2 aspect ratio — which is why A4 scales to A5 with no cropping.

One sheet, six different weights

A metric paper weight is a density: grams per square metre, one number, no context needed. A US paper weight is the weight of five hundred sheets of that paper's parent size — and every kind of paper has a different parent. So the pound number tells you nothing until you know what sort of paper it is.

Grams per square metre

Paper type

Pounds, for that type

At 75 gsm the same paper is 20 lb bond / writing and 51 lb text / book — a factor of 2.54 between two labels for one sheet. That is why 20 lb bond and 50 lb text are very nearly the same paper: 75.2 gsm against 74.0, 1.2 gsm apart. Two numbers that look two and a half times different describe sheets you could not tell apart by hand.

What a weight is actually for

gsm	Feels like	Used for
0–60	Very light	Tracing, airmail, gift tissue, flimsy copies. Shows through badly and jams some printers.
60–90	Everyday	Copier and printer paper, letterheads, notepads. 80 gsm is the usual office default.
90–120	Heavy office	Better letterheads, reports, flyers printed both sides. Noticeably more substantial in the hand.
120–160	Light card	Posters, quality flyers, book covers, origami that needs to hold a crease.
160–220	Card	Greeting card inserts, menus, folders, papercraft that must stand up on its own.
220–300	Card stock	Greeting cards, invitations, tags, die-cutting. Most home cutters handle this range.
300–400	Heavy card stock	Business cards, premium invitations, box making. Needs scoring before folding or it cracks.
400–10000	Board	Mounting board, packaging, model making. Cut rather than folded.

The C series exists for the A series to fit inside

The envelope sizes. Each C sheet is the geometric mean of the A of the same number and the one above it, which is exactly the amount of slack needed for the A sheet to slide in.

Envelope	Size	Takes
C0	917 × 1297 mm	A0 flat
C1	648 × 917 mm	A1 flat
C2	458 × 648 mm	A2 flat
C3	324 × 458 mm	A3 flat
C4	229 × 324 mm	A4 flat
C5	162 × 229 mm	A5 flat
C6	114 × 162 mm	A6 flat
C7	81 × 114 mm	A7 flat
C8	57 × 81 mm	A8 flat
C9	40 × 57 mm	A9 flat
C10	28 × 40 mm	A10 flat

How to use

Find your size in the table.
Read the dimensions in both millimetres and inches.
Check the aspect ratio before scaling artwork.
Add bleed if the design runs to the edge.

Frequently asked questions

Why does folding an A4 sheet give exactly A5?

Because the A series uses an aspect ratio of the square root of two. That is the only ratio where halving the long side produces a rectangle of the same shape, which is what makes scaling between sizes possible without any cropping or distortion.

How big is A0?

Exactly one square metre in area, which is the definition the whole series is built from. Every subsequent size is half the previous one, so A4 is one sixteenth of a square metre. It is an unusually tidy system, which is why it was adopted almost everywhere.

Why does the US use different sizes?

Historical convention that predates the metric series and was never displaced. US Letter is 8.5 by 11 inches with a ratio of about 1.29, which is not the square root of two — so scaling between US sizes crops or leaves margins, and printing an A4 document on Letter always needs adjusting.

What is the difference between A4 and Letter in practice?

A4 is narrower and taller — about 6 mm narrower and 18 mm longer. A document laid out for one will shift on the other, which is why PDFs from overseas often print with a cut-off edge or an odd margin, and why print dialogs offer to scale to fit.

What is bleed and why does it matter?

Extra artwork extending past the trim line, usually 3 mm, so that a slight misalignment in cutting does not leave a white sliver at the edge. Any design where colour or an image runs to the edge needs it, and printers will ask for it.

What is the B series for?

Sizes sitting between the A sizes, used for posters, books and envelopes that need to hold an A size with a little room. B5 is a common book format, and C series envelopes are sized to take A series sheets — a C4 envelope holds an unfolded A4 sheet.

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