Megapixel Calculator
Convert between megapixels and pixel dimensions. See what resolution your camera shoots at, estimate file sizes, and check print quality at different paper sizes.
Image Resolution
Results
Print Quality at Various Sizes
| Print Size | Required DPI | Current DPI | Quality |
|---|---|---|---|
| 4x6 inches | 300 DPI | 660 DPI | Excellent |
| A4 (8.3x11.7 in) | 300 DPI | 324 DPI | Excellent |
| A3 (11.7x16.5 in) | 300 DPI | 230 DPI | Very Good |
| 8x10 inches | 300 DPI | 348 DPI | Excellent |
| 11x14 inches | 300 DPI | 252 DPI | Very Good |
| Poster 24x36 in | 300 DPI | 110 DPI | Fair |
Print Quality Ratings
What Megapixels Actually Tell You
A megapixel is one million pixels, calculated as width times height divided by one million. A 4K image at 3840 x 2160 works out to 8,294,400 pixels, or 8.3MP. The number is useful for two things: knowing whether your file is sharp enough for a print at a given size, and estimating uncompressed file size (around 3MB per megapixel for an RGB JPEG before compression). It is not a sharpness metric on its own. A 50MP medium format file from a Fujifilm GFX has more usable detail than a 50MP cropped phone sensor because the larger photosites collect more light per pixel.
Bayer interpolation muddies the picture too. Every standard camera sensor captures only red, green or blue at each photosite, then the camera interpolates the missing two channels from neighbours. So a 24MP camera does not actually record 24 million full-colour pixels; it records 24 million single-channel measurements and works out the rest. Real resolving power is closer to 70-80% of the headline figure once interpolation is accounted for, which is why a 12MP iPhone photo can look softer than the spec implies when blown up to A3.
Print Quality at Common Sizes (300 DPI Target)
| Print Size | Required Pixels | Required MP | Acceptable from |
|---|---|---|---|
| 6x4 inch | 1800 x 1200 | 2.2MP | Most phone cameras |
| 7x5 inch | 2100 x 1500 | 3.2MP | Most phone cameras |
| A4 (300 DPI) | 2480 x 3508 | 8.7MP | 12MP+ camera |
| A3 (300 DPI) | 3508 x 4961 | 17.4MP | 20MP+ camera |
| A2 (240 DPI) | 3996 x 5664 | 22.6MP | 24MP+ camera |
| Poster 24x36 in | 5760 x 8640 | 49.8MP | Medium format or stitched |
How to Choose Camera Megapixels for Your Work
12MP is enough for Instagram, web display, and prints up to A4 at viewing distance. 24MP gives you cropping room and clean A3 prints, which is why most enthusiast mirrorless bodies sit there. 45-50MP is overkill for general photography but right for landscape work where you want to crop heavily or print A1+. Beyond 50MP you are paying for diminishing returns unless you do commercial product or fine art prints. Wedding photographers in the UK typically charge £1,000 to £3,000 per day and almost universally shoot 24-30MP because the workflow stays manageable.
File size grows linearly with pixel count and quadratically with print size. A 50MP RAW from a Canon R5 is 60MB on disk, a 100MP medium format file is 110-120MB, and editing a wedding's worth of either in Lightroom needs at least 32GB of RAM. Use the calculator to check the uncompressed file size and storage cost before you buy a higher resolution body. Pair with the [pixels to physical size converter](/pixels-to-physical-converter) to translate a target print size back into the megapixel count you genuinely need.
Frequently Asked Questions
How many megapixels do I need for an A4 print?
8.7 megapixels at 300 DPI, which equates to a 2480 x 3508 pixel image. Most modern phones (12MP and up) and any mirrorless camera can produce A4 prints with no resampling needed. If you only need 240 DPI (acceptable for prints viewed at arm's length), the requirement drops to about 5.6MP. The calculator shows current DPI for your image at every standard print size so you can see exactly what holds up.
Are 108MP phone cameras really better than 12MP?
Not always. High-megapixel phone sensors use a technique called pixel binning, where four (or more) tiny photosites are merged into one virtual pixel for low-light shots. The 108MP figure is marketing-led; in default mode the phone outputs around 12-27MP. Daylight sharpness can be slightly better but noise performance, dynamic range and lens limitations matter far more than the headline figure for most users.
Why does my 12MP photo look fuzzy when printed at A3?
12MP is around 4000 x 3000 pixels. At A3 (11.7 x 16.5 inches), that gives 240-250 DPI, which is acceptable but not crisp. For perfect 300 DPI sharpness you would need 17.4MP. The fuzziness is more visible if the original photo had any motion blur, was taken in low light with high ISO, or has been compressed heavily by social media before you saved it back.
How big a file is a 50MP photo?
Uncompressed RGB at 8 bits per channel works out to 150MB for a 50MP image (50 million pixels x 3 bytes). A typical RAW file with compression sits at 50-65MB. A high-quality JPEG from the same image is 12-25MB depending on subject complexity. Storage adds up fast: 1000 50MP RAW files needs around 60GB of drive space.
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