Every ISO 216 size in mm, inches and pixels at 300 ppi, computed the way the standard defines them, plus press sheets and envelopes.
These are computed, not copied
Every dimension on this page is generated from the ISO 216 rule rather than transcribed, and the rule is more subtle than it looks. You do not take the exact geometric value and round it. You seed each series with a base size and then repeatedly halve the long side, rounding down each time.
The difference is not academic. Rounding the exact value to the nearest millimetre gives the wrong answer at A1, A2, A5, A6, A8 and A9; flooring the exact value gives the wrong answer at A0 and A1. A1 is the one size where both shortcuts fail, so it is the tell — a chart that says A1 is 594 × 840 mm was computed the wrong way. It is 594 × 841.
The tolerances are ±1.5 mm below 150 mm, ±2 mm from 150 to 600, and ±3 mm above that. DIN 476 is tighter than ISO on all three.
ISO B and JIS B are different sizes
ISO B is the geometric mean of the two adjacent A sizes, which puts B0 at 1000 × 1414 mm and an area of 1.414 m². JIS B — the Japanese series — is defined by area instead, at 1.5 m², which puts B0 at 1030 × 1456.
They are close enough to look like the same series and far enough apart to matter: ISO B5 is 176 × 250 mm and JIS B5 is 182 × 257. JIS B5 is the standard Japanese book trim, so if you are working on anything printed in Japan this is the distinction that bites. The B series on this page is ISO.
DL is not a C size
DL is 110 × 220 mm and its aspect ratio is exactly 2.0, not the √2 that every ISO size shares. It comes from DIN Lang and it predates its inclusion in the ISO family; ISO 269 defined it and was withdrawn in 2009 without replacement.
So DL does not behave like its neighbours. C6/C5 at 114 × 229 mm takes the same folded A4 and is the size to reach for when you want the envelope to look proportionate to everything else in the mailing.
RA and SRA are the sizes the press actually uses
A press does not print on A4. It prints on an oversized sheet that carries the bleed and the gripper edge, then the job is trimmed down. Those sheets are ISO 217: RA is "raw format A", slightly larger than A; SRA is "supplementary raw format A", larger again.
SRA3 at 320 × 450 mm is the standard sheet on almost every digital press, which is why so many short-run printers quote their maximum finished size as something a little under A3. These sizes are absent from most paper-size charts and they are the ones that determine what your printer can actually do.
Asked often
Why is A4 210 × 297 and not 210 × 297.0?
Because ISO 216 rounds down to whole millimetres at every halving. The exact √2 value for A4 would be 210.22 × 297.30 mm.
What size is A4 in pixels?
At 300 ppi, 2480 × 3508 px. With 3 mm bleed all round it is 2551 × 3579 px. Both are in the table above.
Which B series should I use?
ISO B unless you are printing in Japan. JIS B5 at 182 × 257 mm is the standard Japanese book trim and is 6 mm wider than ISO B5.