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Megapixels to Print Size

Megapixels and aspect ratio in, pixel dimensions and largest sharp print out.

MP
DPI

Print size at 300 DPI

20 × 13.33in

Scale

Not to scale

All results
In centimeters50.8 × 33.87cm
Pixel dimensions (approx.)6,000 × 4,000px
At 150 DPI (posters)40 × 26.67in

Megapixels tell you the pixel count, not the shape. With the camera's aspect ratio you can recover the width and height: a 24 MP 3:2 photo is 6000 × 4000 px, which prints sharply at 20 × 13.33 inches at 300 DPI.

How it works

width (px) = √(megapixels × 1,000,000 × w ÷ h)

print width (in) = width (px) ÷ DPI

Worked example

With a 24 MP camera with a 3:2 sensor, printed at 300 DPI:

  1. Total pixels: 24 × 1,000,000 = 24,000,000.
  2. Width for a 3:2 frame: √(24,000,000 × 3 ÷ 2) = 6,000 ≈ 6000 px; height ≈ 4000 px.
  3. Divide by the DPI: 6,000 ÷ 300 = 20 in wide.

When you need this tool

Deciding what size to order for a print, a canvas or a photo book, or comparing cameras and phones by what they can actually print. Camera specs quote megapixels; print shops want inches or centimeters at a given DPI.

How it’s calculated

  1. Total pixels = megapixels × 1,000,000.
  2. For a w:h shape, the width is √(total × w ÷ h) and the height is width × h ÷ w.
  3. Print size = pixels ÷ DPI.

The pixel dimensions are close approximations; your camera’s exact figures may differ by a few pixels.

Sharp print sizes at 300 DPI

  • 12 MP (4:3): 13.33 × 10 in
  • 24 MP (3:2): 20 × 13.33 in
  • 45 MP (3:2): about 27.4 × 18.3 in

Common mistakes

Cropping and forgetting. A crop from 3:2 to a square 8 × 8 print throws away a third of the pixels. Calculate from the cropped size.

Ignoring viewing distance. Big wall prints are seen from further away, so they need fewer DPI to look sharp.

Related: image print size calculator and DPI calculator.

Questions

How big can I print a 12 MP photo?

A 12 MP 4:3 image (about 4000 × 3000 px) prints at 13.33 × 10 in at 300 DPI, or about twice that size at 150 DPI for a poster.

Do more megapixels always mean bigger prints?

Yes, but slowly: doubling megapixels increases print width by only about 41% (√2).

What aspect ratio does my camera use?

Most DSLRs and mirrorless cameras shoot 3:2. Phones and compacts usually shoot 4:3.

Is 150 DPI good enough?

For posters and wall prints seen from a meter or more, yes. For photo books and small prints, aim for 300 DPI.

Last reviewed 2026-09-24. How we check values · Report a problem with this page

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