Megapixel Calculator
Find out how many megapixels an image has from its width and height, or work out the pixel dimensions behind a camera's MP rating. You also get the aspect ratio, the largest sharp print size and the quality at common print sizes.
Last updated:
Shown alongside 300 and 150 DPI.
How to use the Megapixel Calculator
- Choose a mode: megapixels from width × height, or pixel dimensions from a megapixel count.
- Enter the pixels (for example 6000 × 4000), or the MP rating plus the aspect ratio and orientation.
- Click Calculate megapixels (results also update as you type).
- Read the results: megapixels or dimensions, aspect ratio and the largest print at 300 and 150 DPI.
- Check the print table to see how sharp the image will be at 4 × 6 up to 24 × 36 inches, and download it as CSV.
Megapixel formulas
- Megapixels = width (px) × height (px) ÷ 1,000,000
- Width from MP = √(MP × 1,000,000 × a ÷ b) for an a:b aspect ratio
- Height from MP = width × b ÷ a
- Aspect ratio = width : height, both divided by their greatest common divisor
- Max print size = pixels ÷ DPI (inches), × 2.54 for centimeters
Worked example: a phone photo of 4032 × 3024 pixels has 12,192,768 pixels, or 12.2 MP. The greatest common divisor of 4032 and 3024 is 1008, so the ratio is 4:3. At 300 DPI it prints sharply up to 13.44 × 10.08 inches (34.1 × 25.6 cm).
Common resolutions in megapixels
| Format | Pixels | Megapixels | Ratio | Print at 300 DPI |
|---|---|---|---|---|
| VGA | 640 × 480 | 0.3 MP | 4:3 | 2.1 × 1.6 in |
| HD 720p | 1,280 × 720 | 0.9 MP | 16:9 | 4.3 × 2.4 in |
| Full HD 1080p | 1,920 × 1,080 | 2.1 MP | 16:9 | 6.4 × 3.6 in |
| QHD 1440p | 2,560 × 1,440 | 3.7 MP | 16:9 | 8.5 × 4.8 in |
| 4K UHD | 3,840 × 2,160 | 8.3 MP | 16:9 | 12.8 × 7.2 in |
| DCI 4K | 4,096 × 2,160 | 8.8 MP | 256:135 | 13.7 × 7.2 in |
| 12 MP phone (4:3) | 4,032 × 3,024 | 12.2 MP | 4:3 | 13.4 × 10.1 in |
| 24 MP APS-C / full frame (3:2) | 6,000 × 4,000 | 24.0 MP | 3:2 | 20.0 × 13.3 in |
| 8K UHD | 7,680 × 4,320 | 33.2 MP | 16:9 | 25.6 × 14.4 in |
| 45 MP full frame (3:2) | 8,256 × 5,504 | 45.4 MP | 3:2 | 27.5 × 18.3 in |
| 48 MP phone (4:3) | 8,000 × 6,000 | 48.0 MP | 4:3 | 26.7 × 20.0 in |
| 100 MP medium format (4:3) | 11,648 × 8,736 | 101.8 MP | 4:3 | 38.8 × 29.1 in |
Camera rows are typical examples; exact pixel dimensions vary by model, so check your own photo's width and height for a precise figure.
What megapixels do and don't tell you
- Resolution grows with the square root. Going from 12 MP to 48 MP is four times the pixels but only twice the width and height, so prints can be twice as wide, not four times.
- Cropping costs pixels fast. Cropping a photo to half its width and half its height keeps only a quarter of the megapixels. A 24 MP image cropped that way becomes 6 MP.
- Aspect ratio changes the count. Switching a 4:3 sensor to 16:9 mode trims the top and bottom, so a 12 MP phone shoots about 9 MP in 16:9.
- Pixel binning. Many 48 MP and higher phone cameras combine groups of 4 pixels into one by default, saving 12 MP photos that are cleaner in low light. Use the full-resolution mode when you need the extra detail.
- More MP is not always sharper. Lens quality, focus, motion blur and sensor size affect real detail as much as pixel count. For screens, even 4K displays show only about 8.3 MP, so most online photos are resized well below camera resolution.
Frequently asked questions
How do you calculate megapixels?
Multiply the image width by its height in pixels and divide by 1,000,000. For example, 4032 × 3024 = 12,192,768 pixels, which is about 12.2 megapixels.
How do I convert megapixels to pixel dimensions?
You also need the aspect ratio. Width = √(MP × 1,000,000 × ratio width ÷ ratio height) and height = width × ratio height ÷ ratio width. A 24 MP image at 3:2 works out to about 6000 × 4000 pixels.
How many megapixels is 4K?
4K UHD video frames are 3840 × 2160 pixels, which is about 8.3 megapixels. DCI 4K used in cinema is 4096 × 2160, about 8.8 MP. Full HD (1920 × 1080) is about 2.1 MP.
Does doubling the megapixels double the print size?
No. Megapixels measure area, so twice the megapixels only makes each side about 1.41 times (the square root of 2) longer. To double both the width and height of a print at the same DPI you need four times the megapixels.
How many megapixels do I need for a good print?
At 300 DPI, which is typical for photo prints held in the hand, a 4 × 6 inch print needs about 2.2 MP, 8 × 10 needs 7.2 MP and 16 × 20 needs 28.8 MP. Large prints viewed from farther away usually look fine at 150–200 DPI, which needs a quarter to under half as many pixels.
Why is my camera's actual megapixel count different from the advertised number?
Manufacturers often round the figure and may quote total sensor pixels, including edge pixels not used in the final image. Shooting in a different aspect ratio, such as 16:9 on a 4:3 phone sensor, crops the image and lowers the real count, so enter your photo's actual width and height for the exact value.
Is a megapixel exactly one million pixels?
Yes. In camera and image specs a megapixel is 1,000,000 pixels (not 1,048,576), so this calculator divides the pixel count by one million.
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