Image resolution describes the number of pixels in a photo in megapixels (MP) and determines the print size without loss of quality. More megapixels allow for larger prints and more room for cropping, but they do not automatically improve image quality. For social media, the web, and A4 printing, 12–20 MP is sufficient. dpi (print resolution) and ppi (image resolution) are important terms for image quality.
Category: Photography Basics > 6. Photo Formats & Files Article ID: 6.1 Created: May 2026
The Essentials at a Glance
- Image resolution describes how many pixels a photo contains—specified in megapixels (MP) or as a pixel count (width × height)
- More megapixels allow for larger prints and more flexibility when cropping—but they do not automatically mean better image quality
- For most applications (social media, the web, A4 printing), 12–20 MP is more than enough
Explanation
What Is a Pixel?
A pixel (picture element) is the smallest building block of a digital photo—an individual image point with a specific color and brightness. A photo with 4000 × 3000 pixels contains 12,000,000 pixels = 12 megapixels (MP).
What Does Resolution Mean in Practice?
Resolution determines how large a photo can be printed or displayed without individual pixels becoming visible (the image becomes “pixelated”):
Recommended value for printing: 300 dpi (dots per inch)
| Megapixels | Image Size (Pixels) | Maximum Print Size at 300 dpi |
|---|---|---|
| 2 MP | 1600 × 1200 | approx. 13.5 × 10 cm |
| 5 MP | 2592 × 1944 | approx. 22 × 16 cm |
| 8 MP | 3264 × 2448 | approx. 28 × 21 cm (A4) |
| 12 MP | 4000 × 3000 | approx. 34 × 25 cm (A3) |
| 20 MP | 5184 × 3888 | approx. 44 × 33 cm (A2) |
| 24 MP | 6000 × 4000 | approx. 51 × 34 cm |
Tip: For large formats (A3, A2), the dpi value can be reduced to 150–200 dpi because these images are viewed from a greater distance—the eye can no longer detect the difference.
What Are dpi and ppi?
- dpi (dots per inch): Dots per inch—describes the printer’s print resolution
- ppi (pixels per inch): Pixels per inch—describes the resolution of the digital image
In everyday language, both terms are often (imprecisely) used interchangeably. The standard for quality printing is 300 dpi/ppi.
More Megapixels = Better Quality?
Not automatically. Megapixels are just one of many factors:
- A 12 MP full-frame sensor generally delivers better images in low light than a 24 MP smartphone sensor
- Small pixels produce more noise (→ Article 3.14)
- The lens must be good enough to take advantage of the sensor’s resolution
- Camera shake and focus blur make high megapixel counts worthless
Megapixels are useful for:
- Large prints (A2 and larger)
- Heavy cropping (e.g., wildlife photography when you need to crop afterward)
- Professional production and advertising photography
Megapixels play hardly any role in:
- Social media posts (Instagram and Facebook display a maximum width of 1080 px)
- Web photos (72–150 ppi is sufficient)
- Prints up to A4
Resolution and File Size
The more pixels, the larger the file:
- 12 MP JPEG (compressed): approx. 3–8 MB
- 12 MP RAW (uncompressed): approx. 20–30 MB
- 24 MP RAW: approx. 40–60 MB
Note after cropping: When cropping, pixels are removed—the resolution decreases. Before saving, check whether enough pixels remain for the intended use.
Practical Tip
For social media and the web, 1–2 MP is more than enough—Instagram will reduce a 20 MP photo to approximately 1 MP anyway. If you want to save storage space, you can select a lower resolution setting in the camera when taking photos intended solely for social media. For all other purposes, the rule is: shoot at the highest available resolution and reduce the size selectively during export.