Resolution and Megapixels Explained: How Many Pixels Do You Really Need?

• Full HD (1920 × 1080) is about 2 megapixels.
• 4K (3840 × 2160) is about 8.3 megapixels.
• A typical phone screen is somewhere in between.

For sharing on social media and viewing on phones, even a 12 MP photo has more resolution than you need, and platforms usually resize it.

Resolution for prints

Print quality depends on how many pixels per inch (ppi or dpi) are printed. A common guide for good quality is 300 pixels per inch.

• 4 × 6 inches needs about 1200 × 1800 pixels (2.2 MP).
• 8 × 10 inches needs about 2400 × 3000 pixels (7.2 MP).
• 12 × 18 inches needs about 3600 × 5400 pixels (19.4 MP) at 300 ppi, though large prints viewed from a distance look fine at lower values.

So a 12 MP phone photo is fine for prints up to around A4 or 8 × 10 inches without cropping.

Why cropping matters

Cropping throws away pixels. A photo cropped to half its area is now 6 MP. If you plan to print a photo big, avoid heavy cropping.

More megapixels, better photo?

Not necessarily. Image quality also depends on:

• Sensor size: larger sensors capture more light and produce cleaner images.
• Lens quality: a poor lens limits sharpness, regardless of megapixels.
• Processing: phone software has a big influence on the final look.
• Light: the same camera produces very different results in bright and dim conditions.

Cramming more pixels onto a small sensor can even increase noise in low light.

Upscaling doesn't add detail

Enlarging a small photo makes it bigger, but doesn't create real detail; edges become soft or blocky. Some enhancement tools can improve apparent sharpness, but they can't recover information that wasn't captured.

Downscaling for sharing

If you need to email or upload a photo, reducing its resolution shrinks the file size. For a typical screen, 1600 to 2000 pixels on the long side is plenty.

Resolution in video

Video uses resolution too: 1080p is about 2 MP per frame, and 4K is about 8 MP. Higher resolutions create much larger files.

Common mistakes

• Sharing at full size and creating huge files.
• Cropping too heavily and then printing large.
• Assuming a higher megapixel number always looks better.

Practice

Check the pixel dimensions of a few of your photos, and work out the largest print size each could support at 300 ppi.

Crop, resize and export photos with Cinexa →