Megapixel Calculator: Image Resolution and File Size Estimator
Megapixels measure the total number of pixels in a digital image. One megapixel equals one million pixels, calculated by multiplying the image width by the height and dividing by 1,000,000. A 6,000 x 4,000 pixel image from a typical mirrorless camera produces a 24-megapixel file with a 3:2 aspect ratio. Knowing the megapixel count helps you assess whether a camera meets your needs for large prints, cropping flexibility or commercial use. Beyond megapixels, file size depends on bit depth and color channels. A 14-bit RAW file stores more tonal information than an 8-bit JPEG but takes several times more storage. This calculator computes megapixels and aspect ratio from your image dimensions, then estimates file sizes across the most common formats: uncompressed RAW, JPEG at three quality levels, lossless PNG and uncompressed TIFF. The JPEG estimates use typical compression ratios (quality 95 approximately 4:1, quality 80 approximately 10:1, quality 60 approximately 20:1). Actual sizes vary with image content and camera firmware. Use these estimates for storage planning and memory card capacity calculations.
Resolution: -- MP | Aspect ratio: --
How megapixels and file sizes are calculated
Megapixels: MP = (width x height) / 1,000,000
Aspect ratio: Divide both width and height by their greatest common divisor (GCD) to obtain the simplified ratio. For example, 6,000 x 4,000 shares a GCD of 2,000, giving 3:2.
Uncompressed RAW / TIFF size in bytes: width x height x channels x (bit depth / 8)
JPEG estimates use typical compression ratios for natural photographic content: quality 95 divides RAW by 4, quality 80 divides by 10, quality 60 divides by 20. PNG lossless divides by 2. These are approximations; image content strongly affects the actual result.
Worked example: 24 MP camera, 14-bit RAW, RGB
- MP = (6,000 x 4,000) / 1,000,000 = 24.00 MP
- Aspect ratio: GCD(6000, 4000) = 2,000; ratio = 3:2
- RAW bytes = 6,000 x 4,000 x 3 x (14 / 8) = 6,000 x 4,000 x 3 x 1.75 = 126,000,000 bytes = 120.23 MB
- JPEG q95 estimate = 126,000,000 / 4 = 31,500,000 bytes = 30.06 MB
Common camera resolutions reference
| Camera class | Resolution | Megapixels | Aspect ratio |
|---|---|---|---|
| Entry-level / smartphone | 4,000 x 3,000 | 12 MP | 4:3 |
| Mid-range mirrorless / DSLR | 6,000 x 4,000 | 24 MP | 3:2 |
| High-resolution mirrorless | 8,256 x 5,504 | 45 MP | 3:2 |
| Full-frame high-resolution | 9,504 x 6,336 | 61 MP | 3:2 |
| Medium format | 11,648 x 8,736 | 102 MP | 4:3 |
Megapixel calculator: frequently asked questions
What is a megapixel?
A megapixel (MP) is one million pixels. It is calculated by multiplying the image width in pixels by the image height in pixels and dividing by 1,000,000. For example, an image that is 6,000 x 4,000 pixels contains 24,000,000 pixels, which equals 24 megapixels. Camera manufacturers use megapixel count to describe sensor resolution.
How many megapixels do I need?
For everyday photography and social media, 12 megapixels is more than sufficient. For large print work (A2 and above at 300 dpi), you need roughly 24 megapixels or more. Professional studio and commercial work often uses 45 to 102 megapixels. More megapixels give you more flexibility to crop and still have enough resolution for large prints, but they also produce larger file sizes and require more storage.
What is the file size of a RAW photo?
RAW file size depends on sensor resolution, bit depth and color channels. The uncompressed RAW size in bytes is: width x height x channels x (bit depth / 8). For a 24 MP camera (6,000 x 4,000) shooting 14-bit RAW with 3 channels, the uncompressed size is 6,000 x 4,000 x 3 x 1.75 = 126 MB. Most cameras apply lossless compression, reducing this to roughly 20 to 45 MB in practice.
Does more megapixels mean better quality?
Not necessarily. Megapixels determine resolution (detail and crop latitude) but not overall image quality. Other factors, including sensor size, pixel size, lens quality, dynamic range and noise performance, often matter more. A large sensor with 12 MP can outperform a small sensor with 50 MP in low-light situations. More megapixels are most useful when you need to print very large or crop heavily.
What is the best file format for photography?
RAW (camera-specific) is best for maximum editing flexibility, as it retains all sensor data. TIFF is lossless and good for archiving edited images. PNG is lossless and ideal for graphics and screenshots. JPEG at quality 80 to 95 is the best choice for sharing and web use, as it provides a good balance between file size and visual quality. JPEG is lossy: each re-save degrades quality slightly, so always keep a lossless master.
Official sources
- Wikipedia: Image resolution.
- DPBestflow: RAW files. American Society of Media Photographers digital workflow resource.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. File size estimates are approximations only.