A0 at 300 DPI is 9933 × 14043 pixels

A0 (841 × 1189 mm) at 300 DPI is 9933 × 14043 pixels, which is 139 megapixels.

Portrait9933 × 14043 pixels
Landscape14043 × 9933 pixels
With 3 mm bleed10004 × 14114 pixels
Megapixels139
Aspect ratio1.41:1 (1 to √2 before rounding)
File size399 MB as uncompressed 8-bit RGB; a JPEG or PNG is smaller
Paper size841 × 1189 mm (33.11 × 46.81 in)

The working

Pixels are inches multiplied by the resolution, and an inch is 25.4 mm.

Bleed is extra image past the trim line, so that a cut that lands slightly off still leaves ink to the edge. Print shops usually ask for 3 mm on every side of an A-series page, which makes the file 10004 × 14114 pixels.

Is your photo big enough?

To fill A0 at 300 DPI an image needs at least 9933 × 14043 pixels. Cropped to fill the sheet:

At 300 DPI the pixels of a print blend together from about 11.5 inches (29 cm) away. 300 DPI is the standard for print that is held in the hand: books, magazines, photo prints, business cards and flyers. At reading distance the eye can no longer pick out the pixels.

A0 at other resolutions

ResolutionPixelsWith bleedMegapixelsUncompressed
72 DPI2384 × 33702401 × 3387823 MB
96 DPI3179 × 44943201 × 45171441 MB
100 DPI3311 × 46813335 × 47051544 MB
150 DPI4967 × 70225002 × 705735100 MB
200 DPI6622 × 93626669 × 940962177 MB
240 DPI7946 × 112358003 × 1129189255 MB
300 DPI9933 × 1404310004 × 14114139399 MB
400 DPI13244 × 1872413339 × 18819248709 MB
600 DPI19866 × 2808720008 × 282285581.56 GB
1200 DPI39732 × 5617340016 × 564572,2326.24 GB

Other sizes at 300 DPI

A0 is one square metre of paper, used for technical drawings and large posters. See A0 in pixels at every resolution or everything at 300 DPI.