A0 at 150 DPI is 4967 × 7022 pixels

A0 (841 × 1189 mm) at 150 DPI is 4967 × 7022 pixels, which is 35 megapixels.

Portrait4967 × 7022 pixels
Landscape7022 × 4967 pixels
With 3 mm bleed5002 × 7057 pixels
Megapixels35
Aspect ratio1.41:1 (1 to √2 before rounding)
File size100 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 5002 × 7057 pixels.

Is your photo big enough?

To fill A0 at 150 DPI an image needs at least 4967 × 7022 pixels. Cropped to fill the sheet:

At 150 DPI the pixels of a print blend together from about 22.9 inches (58 cm) away. 150 DPI is a common minimum for posters and large prints seen from a step or two away, and a usual setting for scanning documents that only need to be read.

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 150 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 150 DPI.