By Ahsan Khowaja · Updated 27 October 2026
How to use the megapixel calculator
- Pick what you already know. Most people have a width and height in pixels (from the photo's file properties or a camera spec sheet) and want the megapixels. If you only know the megapixel count, switch to the second mode and choose the aspect ratio of the camera: 4:3 for phones and compact cameras, 3:2 for DSLR and mirrorless cameras, 16:9 for video frames.
- Type the numbers. Commas are fine, so 4,032 and 4032 both work.
- Read the result: the megapixels (or the width and height), the exact pixel count, the aspect ratio, and the largest print at 300, 240, 200 and 150 PPI.
On Windows the pixel dimensions are under right-click › Properties › Details; on a Mac, open the photo in Preview and use Tools › Show Inspector. Our guide to reading photo metadata shows where phones hide the same figures.
How to calculate megapixels
A megapixel is one million pixels. Multiply the width by the height to get the total number of pixels, then divide by 1,000,000:
Megapixels = width × height ÷ 1,000,000
- 4032 × 3024 = 12,192,768 pixels, which is 12.19 MP. This is the size most 12 MP phone cameras produce.
- 1920 × 1080 = 2,073,600 pixels, so a Full HD frame is 2.07 MP.
- 6000 × 4000 = 24,000,000 pixels, exactly 24 MP, the file size of many 24 MP cameras.
- 1000 × 1000 = 1,000,000 pixels: a 1000-pixel square is exactly 1 MP.
The figure is decimal, so 1 MP means 1,000,000 pixels and not 1,048,576 (2²⁰). Camera makers count the same way. Their spec sheets list "effective pixels", which is the number of sensor pixels used to form the picture; the JPEG you actually get can be a little smaller or larger than the headline number. A camera sold as 24.2 MP typically writes 6000 × 4000 files, which is 24.0 MP.
How many pixels is 12MP? Megapixels of common sizes
The megapixel resolution of a photo depends on its shape as well as its pixel count. This table lists the sizes you are most likely to meet, with the exact pixel total for each.
| Megapixels | Typical size (px) | Total pixels | Shape | Where you see it |
|---|---|---|---|---|
| 0.92 MP | 1280 × 720 | 921,600 | 16:9 | 720p HD video |
| 2.07 MP | 1920 × 1080 | 2,073,600 | 16:9 | Full HD video, 1080p screenshots |
| 3.69 MP | 2560 × 1440 | 3,686,400 | 16:9 | 1440p (QHD) monitors |
| 8.29 MP | 3840 × 2160 | 8,294,400 | 16:9 | 4K UHD video and TVs |
| 12 MP | 4000 × 3000 | 12,000,000 | 4:3 | Many compact cameras and drones |
| 12.19 MP | 4032 × 3024 | 12,192,768 | 4:3 | 12 MP phone cameras |
| 24 MP | 6000 × 4000 | 24,000,000 | 3:2 | Entry and mid-range interchangeable-lens cameras |
| 33.18 MP | 7680 × 4320 | 33,177,600 | 16:9 | 8K UHD video |
| 45 MP | 8192 × 5464 | 44,761,088 | 3:2 | High-resolution full-frame cameras |
| 60.2 MP | 9504 × 6336 | 60,217,344 | 3:2 | 61 MP full-frame cameras |
So "how many pixels is 12MP" has two answers: 12,000,000 pixels by definition, and in practice a 4000 × 3000 or 4032 × 3024 photo. If a phone lists 48 MP but saves 12 MP photos by default, that is pixel binning: four sensor pixels are combined into one output pixel, and the saved file is still 4000 × 3000 or thereabouts.
Megapixel to pixel converter: width and height from a megapixel count
Going the other way needs the aspect ratio, because 12 million pixels can be arranged as a 4000 × 3000 rectangle, a 3464 × 3464 square or a 4619 × 2598 widescreen frame. The calculator uses this megapixel to pixel converter formula:
Width = √(megapixels × 1,000,000 × ratio), where ratio = width ÷ height of the shape, and height = width ÷ ratio.
Worked examples:
- 12 MP at 4:3: width = √(12,000,000 × 1.333) = √16,000,000 = 4000 px; height = 4000 × 3 ÷ 4 = 3000 px.
- 24 MP at 3:2: width = √(24,000,000 × 1.5) = √36,000,000 = 6000 px; height = 6000 × 2 ÷ 3 = 4000 px.
- 8 MP at 16:9: width = √(8,000,000 × 1.778) = √14,222,222 = 3771.2, height = 3771.2 × 9 ÷ 16 = 2121.3, so 3771 × 2121 px after rounding to whole pixels.
The result is rounded because an image can only have whole pixels, so the pixel total can land a few thousand pixels either side of the round megapixel figure. That is normal; real cameras do the same thing.
Megapixels to print size
Print size is pixels divided by pixels per inch, so the megapixels to print size question always needs a PPI. 300 PPI is the usual target for prints held in the hand; 240 PPI still looks sharp; 150 PPI is fine for posters viewed from a metre or more. The calculator shows all of them, and here are the largest prints at 300 PPI for the common counts:
| Megapixels (shape) | Pixels | Largest print at 300 PPI | At 150 PPI |
|---|---|---|---|
| 2.07 MP (16:9) | 1920 × 1080 | 6.4 × 3.6 in | 12.8 × 7.2 in |
| 8.29 MP (16:9) | 3840 × 2160 | 12.8 × 7.2 in | 25.6 × 14.4 in |
| 12 MP (4:3) | 4000 × 3000 | 13.3 × 10 in | 26.7 × 20 in |
| 12.19 MP (4:3) | 4032 × 3024 | 13.44 × 10.08 in | 26.9 × 20.2 in |
| 24 MP (3:2) | 6000 × 4000 | 20 × 13.3 in | 40 × 26.7 in |
| 45 MP (3:2) | 8192 × 5464 | 27.3 × 18.2 in | 54.6 × 36.4 in |
To see whether a particular photo can make a specific print such as 8 × 10 or A4, including how much gets cropped when the shapes differ, use the print size calculator. For large wall prints, the poster size calculator also takes viewing distance into account.
What the megapixel count does not tell you
Megapixels measure how many pixels a photo has, not how good they are. Two 12 MP photos can look very different:
- Sensor size. A full-frame sensor is many times the area of a phone sensor, so at the same 12 MP each of its pixels is far larger, collects more light and shows less noise in dim scenes. The crop factor calculator compares sensor sizes.
- Lens and focus. A soft lens or a missed focus wastes pixels: the file is still 12 MP, but the detail isn't there.
- Compression. A heavily compressed JPEG keeps its pixel dimensions but loses fine texture. The megapixel count stays the same; the quality doesn't.
- File size. Megapixels do not fix the file size in MB. A 12 MP JPEG is typically 2–6 MB depending on the scene and compression level, while the same photo saved as uncompressed 8-bit RGB is 12.19 million × 3 bytes = 36.6 MB. Use the image size calculator for file-size estimates and the photo storage calculator to plan a phone or card.
For sharing online, the extra megapixels are mostly wasted: a 4K screen shows at most 8.3 MP, and a phone screen far less. Our image resizer shrinks a photo to the pixels you actually need, and the image compressor reduces the file size without changing the dimensions.
Camera megapixel calculator: reading a spec sheet
When a camera megapixel calculator result doesn't match the box, check which figure you compared. Spec sheets quote total pixels (every photosite on the sensor, including masked edge pixels used for calibration), effective pixels (the ones that form the picture) and sometimes recorded pixels (the actual file size). Only the last one is what the formula above gives you. Video modes are different again: a camera that shoots 4K video records 3840 × 2160 frames, 8.29 MP, whatever its stills resolution is.
