A3 at 300 DPI in pixels: 3508 × 4961

A3 at 300 DPI is 3508 × 4961 pixels

A3 (297 × 420 mm) at 300 DPI is 3508 × 4961 pixels, which is 17 megapixels.

Portrait	3508 × 4961 pixels
Landscape	4961 × 3508 pixels
With 3 mm bleed	3579 × 5031 pixels
Megapixels	17
Aspect ratio	1.41:1 (1 to √2 before rounding)
File size	50 MB as uncompressed 8-bit RGB; a JPEG or PNG is smaller
Paper size	297 × 420 mm (11.69 × 16.54 in)

Portrait

3508 × 4961 pixels

Landscape

4961 × 3508 pixels

With 3 mm bleed

3579 × 5031 pixels

Megapixels

Aspect ratio

1.41:1 (1 to √2 before rounding)

File size

50 MB as uncompressed 8-bit RGB; a JPEG or PNG is smaller

Paper size

297 × 420 mm (11.69 × 16.54 in)

The working

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

Width: 297 mm ÷ 25.4 = 11.693 in; 11.693 in × 300 = 3,507.9, which rounds to 3508 pixels.
Height: 420 mm ÷ 25.4 = 16.535 in; 16.535 in × 300 = 4,960.6, which rounds to 4961 pixels.

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 3579 × 5031 pixels.

Is your photo big enough?

To fill A3 at 300 DPI an image needs at least 3508 × 4961 pixels. Cropped to fill the sheet:

A 12 megapixel phone photo (4000 × 3000) gives 242 DPI: short of 300, so it would be upscaled or printed softer.
A 24 megapixel camera photo (6000 × 4000) gives 342 DPI: enough.
A 48 megapixel photo (8000 × 6000) gives 484 DPI: enough.

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.

A3 at other resolutions

Resolution	Pixels	With bleed	Megapixels	Uncompressed
72 DPI	842 × 1191	859 × 1208	1	2.9 MB
96 DPI	1123 × 1587	1145 × 1610	1.8	5.1 MB
100 DPI	1169 × 1654	1193 × 1677	1.9	5.5 MB
150 DPI	1754 × 2480	1789 × 2516	4.3	12 MB
200 DPI	2339 × 3307	2386 × 3354	7.7	22 MB
240 DPI	2806 × 3969	2863 × 4025	11	32 MB
300 DPI	3508 × 4961	3579 × 5031	17	50 MB
400 DPI	4677 × 6614	4772 × 6709	31	89 MB
600 DPI	7016 × 9921	7157 × 10063	70	199 MB
1200 DPI	14031 × 19843	14315 × 20126	278	797 MB

A3 is two A4 pages side by side, used for small posters, drawings and spreads. See A3 in pixels at every resolution or everything at 300 DPI.

A3 at 300 DPI is 3508 × 4961 pixels

The working

Is your photo big enough?

A3 at other resolutions

Other sizes at 300 DPI