Key takeaways
- Megapixels = width × height ÷ 1,000,000: 12.19 MP for a 12,192,768 pixel phone photo.
- Megapixels do not set the file size: our four test pictures saved as JPEG at 70% were 66 to 108 KB per megapixel.
What megapixels do and do not tell you
Megapixels count pixels, not quality. A larger sensor, better lens and better light matter as much as the count, and a file size depends on the detail in the picture.
For printing, divide the pixel sizes by the print resolution: at 300 DPI each inch needs 300 pixels. The calculator shows the size that results.
Scenarios
| Scenario | Megapixels | Aspect ratio | At 300 DPI this prints |
|---|---|---|---|
| 4032 × 3024 (phone) | 12.19 MP | 4:3 | 13.4 × 10.1 inches |
| 6000 × 4000 (24 MP camera) | 24.00 MP | 3:2 | 20.0 × 13.3 inches |
| 1920 × 1080 | 2.07 MP | 16:9 | 6.4 × 3.6 inches |
| 3840 × 2160 (4K frame) | 8.29 MP | 16:9 | 12.8 × 7.2 inches |
| 1080 × 1350 | 1.46 MP | 4:5 | 3.6 × 4.5 inches |
Measured: JPEG bytes per megapixel
Four public domain pictures saved as JPEG at 70% quality with the browser encoder (the image compressor's default).
| Picture | Size | Megapixels | JPEG at 70% | Per megapixel |
|---|---|---|---|---|
| NASA | 3840 × 3877 | 14.9 MP | 1.60 MB | 108 KB |
| NASA | 2122 × 2644 | 5.6 MP | 505 KB | 90 KB |
| Gettysburg Address | 3827 × 1588 | 6.1 MP | 563 KB | 93 KB |
| NASA | 5380 × 5432 | 29.2 MP | 1.92 MB | 66 KB |
The spread comes from the content: smooth areas compress far better than fine detail.